Day 2 :
Keynote Forum
Richard M. Kellogg
University of Groningen, Netherlands
Keynote: Attrition-induced deracemization of racemizable crystal-liquid suspensions for the production of industrially relevant compounds
Time : 09:10-09:50
Biography:
Richard M. Kellogg was professor of chemistry at the University of Groningen in The Netherlands for 25 years. He co-founded the contract research organization Syncom BV for which he is still scientific advisor. He is also chief scientific officer of Philae Pharmaceuticals, a company devoted the use of RNA technology for the treatment of skin diseases.
Abstract:
It has been demonstrated that certain chiral racemic compounds sensitive to catalyzed racemization in solution, when subjected to strong grinding as suspensions, deracemize entirely. A strict additional requirement is that the compounds be conglomerates. How does this happen? It is thought that relatively rare primary nucleation of the racemic conglomerate provides a crystal that must have single handedness. Rapid secondary nucleation under conditions whereby growing crystals are continuously shattered leads to rapid propagation of that handedness. The process resembles closely Ostwald Ripening. The direction of deracemization can be determined by addition of a small amount of enantiomerically pure seed crystal. This process has been used to generate single enantiomers of commercially interesting compounds such as Naproxen, Clopidogrel and Prasugrel. Various extensions of this methodology have been developed and also methods for scale up have been developed both by us and by others.
Keynote Forum
Alexandre Urzhumtsev
Université de Lorraine, France
Keynote: Macromolecular computational crystallography: looking forward (and backward)
Time : 09:50 - 10:30
Biography:
Alexandre Urzhumtsev is a full professor at the Université de Lorraine, Nancy, and a researcher at the IGBMC, Illkirch, France. After the Kolmogorov’s physico-mathematical school-internat and the Faculty of Computational Mathematics at the Moscow State University, he moved to Pushchino, Russia, where he got his PhD in X-ray macromolecular crystallography. His main research interests are the development of computational methods and programmes for structure solution, refinement and validation, as well as solution of ‘difficult’ structures where development and application of original algorithms are required.
Abstract:
Addressing to more and more difficult problems of molecular structural biology requires development of new methodological, mathematical and computational tools. For macromolecular crystallography, that is one of the principal methods for the structure determination, the well-known lines of development are automation, structure analysis at very high and at very low resolutions, as well as model and data validation. Other developments are relevant to determination of very large or / and very flexible structures. There is also an evolution of crystallographic tools with a goal to apply them to non-crystallographic samples like isolated objects in XFEL or cryo electron microscopy images. In general, integration of other structural techniques with macromolecular crystallography is an onging process.rnrnWhile completely new and original ideas are required to go forward, some structural problems of macromolecular crystallography could be addressed by ‘recycling’ the tools and ideas known for a while. However, sometime their routine use may result in misleading or in meaningless results. This requires properly revisiting the corresponding tools and notions.rnrnThe talk will develop these issues illustrating them by several practical examples.rnrn
- Track 1: Advanced Crystallography
Track 2: Crystallography in Biology
Track 6: Recent development in the X-ray studies
Track 7: Crystallography Applications
Location: Houston
Chair
Gerd Kaupp
University of Oldenburg, Germany
Session Introduction
Victor Ovcharenko
International Tomography Center, Russia
Title: Breathing crystals-P, T-induced dynamics of heterospin crystals
Time : 11:40-12:05
Biography:
Victor Ovcharenko is the Head of Multispin Coordination Compounds Laboratory at the International Tomography Centre. He has published more than 200 papers in reputed journals (coordination chemistry of free radicals, design of molecular magnets, spin transitions).
Abstract:
The results of studies of magnetostructural correlations inherent in heterospin coordination compounds of transition metals with stable nitroxides were discussed. When the temperature changes, the compounds undergo structural rearrangements accompanied by magnetic effects similar to spin crossover. The magnetic effects that appear as a result of the structural rearrangement of the crystal are determined by the spatial dynamics of the coordination units containing exchange clusters (Jahn-Teller metal ion-coordinated organic radical) and generally involve considerable changes in the crystal volume during repeated cooling-heating cycles. Mechanical stability of heterospin crystals are capable of being reversibly compressed, and expand during multiple crossing of the temperature range of the phase transition region which is reflected by the term "breathing crystals." The plasticity of the single crystals allows studies of reversible SC–SC phase transformations over a wide temperature range (30-300 K), the creation of X-ray cinema, and analysis of structural transformations in the four-dimensional space (coordinates + temperature). The report discusses methods of control over the character and temperature of spin transition for compounds from this class. The effect of a change in the external pressure on the character of the temperature dependence of the effective magnetic moment was also discussed. The phase transformation of the heterospin compound caused by its cooling may be accompanied by deep coloring of the solid phase, which is an unusual effect. The possibility of creating spin devices whose working mechanism (unit) is an exchange cluster, that changes multiplicity under the action of temperature, pressure, or light was discussed.
Yanli Wang
Institute of Biophysics, Chinese Academy of Sciences, China
Title: Structure-based mechanistic insights into PAM-dependent spacer acquisition for incorporation into the CRISPR array
Time : 12:05-12:30
Biography:
Yanli Wang has completed her PhD from University of Science and Technology of China and Post-doctoral studies from Memorial Sloan-Kettering Cancer Center. She is a Principle Investigator of Institute of Biophysics, Chinese Academy of Sciences. She has published more than 25 papers in reputed journals and has been serving as an Editorial Board Member of Non-Coding RNA.
Abstract:
Bacteria obtain a memory of viral invaders by incorporating their DNA sequence elements into the host CRISPR locus, generating a new 33-nt spacer within the CRISPR array. We report on the crystal structure of a Cas1-Cas2-dual-forked DNA complex in efforts towards understanding how the protospacer is selected for insertion into the CRISPR locus. Our structure of the complex reveals a protospacer DNA containing a 23-bp duplex bracketed by tyrosine residues, together with anchored flanking 3’-overhang segments. The complementary PAM sequence in the 3’-overhangs are recognized by Cas1a catalytic subunits in a base-specific manner for protospacer selection and subsequent cleavage at positions 5-nts from the duplex boundary, thereby generating a 33-nt DNA intermediate for incorporation into the CRISPR array. Upon protospacer binding, the Cas1-Cas2 complex undergoes a significant conformational change, generating a flat surface conducive to proper protospacer recognition. Overall, our studies reveal unanticipated structure-based mechanistic insights into PAM-dependent spacer acquisition.
Nobuo Kamiya
Osaka City University, Japan
Title: Two alternative structures of oxygen-evolving complex in photosystem II found by X-ray crystallography at extremely low doses
Time : 12:30-12:55
Biography:
Nobuo Kamiya has completed his PhD from Nagoya University, Japan and Post-doctoral studies from Photon Factory (PF), High Energy Accelerator Research Organization (KEK). He has done his research on Photosystem II. He has constructed Structural Biology Beamlines at PF and SPring-8. At present, he is a Professor of the OCU Advanced Research Institute for Natural Science and Technology (OCARINA), Osaka City University, and is continuing X-ray crystal structure analyses of proteins relating to photosynthesis.
Abstract:
Oxygen-evolving complex (OEC) is the heart of photosystem II (PSII), which extracts electrons from water molecules using solar light energy in photosynthesis. Crystal structure of PSII has been resolved at a resolution of 1.9 Å (Umena, Kawakami, Shen and Kamiya, Nature (2011)), and chemical formula of OEC is fixed as Mn4CaO5 (H2O)4 for the first time. Based on the structural information (PDB-ID: 3WU2), researchers make efforts to elucidate the mechanism of oxygen-evolving reactions in OEC according to the Kok cycle model and to develop new catalysts for water splitting, which are required in artificial photosynthesis. Because OEC is highly sensitive to X-ray irradiation, however, X-ray reduction of OEC and structure change inductions have been discussed on the results from XAFS and DFT computational studies for the past five years. In order to overcome the X-ray reduction problem, we prepared highly isomorphous crystals of PSII and succeeded recently to collect two datasets of diffraction intensities at extremely low doses of 0.06 and 0.24 MGy (0.81 MGy for the previous dataset) at beamlines of SPring-8, BL38B1 and BL44XU. Obtained structures were compared with each other and with 3WU2, and two alternative structures of OEC were found in two monomers in an asymmetric unit of crystal. I will discuss in my talk about the meanings of the alternative structures and X-ray reduction effects on OEC
Jintaek Gong
Korea Advanced Institute Science and Technology, Korea
Title: Structure determination from powder diffraction data of self-assembled structures consisting of beta-peptide foldamers
Time : 16:20-16:40
Biography:
Jintaek Gong has received his Bachelor of Science degree (Magna Cum Laude) in Chemistry from the Korea Advanced Institute of Science and Technology (KAIST)in 2011. He is now pursuing his Integrated MSc and PhD Program in the Department of Chemistry. He has published seven papers in reputed journals and has served as a Powder Crystallographer in the Biomimetic Organic Laboratory of KAIST.
Abstract:
A well-designed beta-peptide foldamer can self-assemble to create various well-defined 3D architectures in aqueous solutions, named as foldecture. The term foldecture is combination of the words foldamer and architecture. Our group has reported unprecedented shapes of foldectures, such as a windmill and a molar tooth. These were highly homogenous both in terms of their size and in terms of morphology. Furthermore, to explore their potential use as functional materials, we recently published a study in which carboxyl groups were exposed to specific rhombic facets of foldectures. We found new potential capabilities of foldecture in relation to their mechanical properties as well as an anisotropic shape of a micro-sized container through the creation of a hollow cavity. Meanwhile, research on the functionalization of foldectures is expanding, as comprehending the self-assembly process and the resulting 3D shapes requires additional work. Hence, the structural determination of the molecular packing structure of foldecture is essential. In relation to this, the powder X-ray diffraction technique has been utilized here due to the dimensions and kinetically experimental conditions of foldecture. A PXRD analysis with synchrotron radiation was adequate to determine the packing structure with well-organized bonds and angle restraints. Further, it was able to designate the absolute orientation of the foldamers involved based on the predicted preferred orientation approximation. The use of a PXRD analysis on foldecture aided the understanding of the shape and properties of the newly formed foldecture and can be expected to play a major role in designing original examples of foldecture in the future.
Kakoli Bose
Tata Memorial Centre, India
Title: Structural insights into mode of regulation of serine protease HtrA2
Time : 15:55-16:20
Biography:
Dr. Kakoli Bose is Principal Investigator and Assistant Professor at ACTREC which is a premier organization of the country dedicated to cancer research and patient care. Dr. Bose completed her graduate studies at North Carolina State University, Raleigh and postdoctoral training at Tufts New England Medical Centre, Boston. Dr. Bose’s research interest focuses on non-classical mechanisms of programmed cell death with emphasis on understanding structure-function relationship of proteins involved in novel adapter-independent extrinsic pathways and caspase-independent apoptosis with the aim of targeting them for disease intervention.
Abstract:
High-temperature requirement protease A2 (HtrA2), a proapoptotic serine protease is involved in maintaining mitochondrial homeostasis. This multifaceted protein has been implicated in several diseases including cancer and neurodegeneration thus making it an important therapeutic target. HtrA2 comprises a short N-terminal region, a serine protease domain and regulatory PDZ (protein-protein interaction) domain. The complex trimeric structure, intricate PDZ-protease crosstalk, allosteric mechanism of activation that is mediated both through its N- as well as C-termini, and most importantly its involvement in both caspase-dependent as well as independent apoptotic mechanism has made this protease an important molecule for biomedical research. Unlike other members of the family, human HtrA2 has been found to be activated through its short N-terminal region in addition to the classical substrate/adapter binding pocket in the PDZ domain. Interaction with inhibitor of apoptosis proteins (such as XIAP) through its N-terminus, leads not only to subsequent cleavage of the molecule but also simultaneous activation of HtrA2, suggesting a ‘positive feedback’ mechanism. Similar mechanism is observed for PDZ-mediated substrate binding and activation as well. Therefore, understanding this complex mechanism and identifying the dual regulatory switch of its allosteric activation will help devise modulators with desired characteristics for therapeutic intervention against diseases it is associated with. It will also shed light on how point mutations lead to its inactivation as observed in diseases such as Alzheimer’s and Parkinson’s. Keeping these in mind, here we aim at understanding the structural correlates of mode of activation of HtrA2 and several pathogenic mutants (in complex with substrates) at atomic level using X-ray crystallography and biophysical probes
Geeta Hundal
Guru Nanak Dev University, India
Title: Hydrated nickel(II) ions: The new secondary building units for the formation of 2D and 3D cationic water networks
Time : 12:55-13:20
Biography:
Geeta Hundal has done her Ph. D from Guru Nanak Dev University in the field of small molecule crystallography. She did her post doctoral research for two years in the same field at CSIC, Rocasolano, Madrid, Spain and stayed in South Korea for two years as Brain-pool scientist in the Korean Research Institute of Chemical Technology She is presently a professor in the department of Chemistry, Guru Nanak Dev University, Amritsar, India. She has published 145 research papers in journals of international repute. Besides crystallography her other interesst are chemical sensing, supramolecular chemistry and coordination chemistry.
Abstract:
As supramolecular assemblies, water molecules may just act as fillers by accommodating the interstitial voids or be a part of the self-assembled architecture themselves. The inter- and intramolecular H-bonds in various water clusters have been found to lie between -9 and -32 kJ mol-1 and -10 to -100 kJ mol-1, respectively, and for both, the data invariably depends on the O···O cutoff being considered. Therefore, the major role of understanding water cluster chemistry is played by X-ray crystallography. One of the aims of these structural studies on water clusters has been to accurately characterize them as various structural motifs. We have found that [Ni(H2O)6]2+ has the ability to form self-assembled supramolecular structures with lattice water molecules and demonstrate yet another unique modes of the cooperative association of water molecules, forming 2D and 3D cationic layers of water molecules. The anions are forming either alternate H-bonded layers with the 2D water layers or are sitting in the huge channels present in the open 3D network of water molecules. Such structural studies are helpful in understanding the nature and role of various water clusters in biological systems, where assorted metal ions are involved in diverse biological functions in an aqueous environment.
Dilano K Saldin
University of Wisconsin, USA
Title: Structure determination by correlated scattering
Time : 15:10-15:35
Biography:
D K Saldin has completed his DPhil from the University of Oxford, UK. After some Post-doctoral work at Oxford, he took up a position of a Research Fellow at Imperial College, London from 1981-1988. In 1988, he joined the Physics department of the University of Wisconsin-Milwaukee, where he currently holds the title of a Distinguished Professor.
Abstract:
In general what are measured on X-ray scattering are the intensities of X-rays. What is more if the scattering units are all identical and identically oriented; a measurable intensity is found from the unit cell even with relatively weak X-rays. Ingenious methods have been devised in X-ray crystallography for deducing the phases of the scattered X-rays and consequently the amplitudes of scattering. A Fourier transform of the scattered amplitudes gives the electron density of the unit cell and this often allows the structure to be deduced. The advent of the new X-ray sources such as those from an X-ray free electron laser (XFEL) allows a paradigm shift for the measurement of molecular structure. The increase in intensity of 10 billion-fold allows the possibility of structure determination even if proteins do not form crystals by scattering of individual molecules. A translation of the molecule gives rise to exactly the same intensities, but as rotation in general changes the intensities totally. However, even in the case of rotation a quantity called the angular correlations, while dependent on the structure, do not depend on the state of rotation or translation and is thus, ideally placed to allow structure determination of molecules typically injected into an XFEL in the form of particles of constant structure but unknown orientation or position. What is more, the absence of translational periodicity as in a crystal, allows the determination of the phases of the scattered amplitudes by an iterative phasing algorithm. We will discuss the use of angular correlations to determine the structures of proteins and viruses, with an XFEL.
Hélène Déméné
Centre de Biochimie Structurale, France
Title: Structural insights into the activation process of the opioid mu receptor
Time : 14:20-14:45
Biography:
Hélène Déméné has completed her PhD from Université Paris six and Post-doctoral studies at the Mount Sinai Hospital (New York, US) and at the Institut de Biologie Structurale (Grenoble, France). She is now Research Associate at the Centre of Biochimie Structrale (Montpellier, France) where she specialized in the Structural Biology of GPCRs. She has published more than 25 papers in reputed journals.
Abstract:
Opioid receptors (OR), members of the G protein-coupled receptor (GPCR) superfamily, constitute the major target for the treatment of pain. The use of opioid drugs acting at these receptors is however a leading cause of death by overdose in Europe and North America. Our collaborators recently described the structure of an antagonist-bound inactive and agonist bound conformation of the µOR. It demonstrated the key molecular determinants for ligand binding and activation process common to other GPCRs. However, much remains to be learned about the mechanisms by which different agonists can induce distinct levels of Gi protein activation and/or arrestins recruitment upon activation of µOR. Pharmacological and biophysical studies suggest that this versatility can be achieved through the structural plasticity of GPCRs. In this work, we analyse the conformational landscape of the µOR in distinct pharmacological conditions (full and partial agonists, antagonist) using liquid-state NMR spectroscopy in light of the X-ray structures. We also investigate the structure and dynamics changes upon binding the effector Gs protein and a mimetic nanobody thereof. Our results show that there is very weak allosteric coupling between the agonist binding pocket and G protein coupling interface. Furthermore, the analysis provides clues on the successive structural events leading to the full active conformation of mOR. We can extend this approach to biased ligands that are able to elicit G-protein activation without arrestin activation. A better knowledge of the structural basis of all activation pathways for opioid drug efficacy may lead to new therapeutic approaches with limited side effects.
Mandeep Sekhon
University of California, USA
Title: Numerical simulation of liquid phase diffusion growth of SiGe single crystals using fixed and dynamic grid techniques: A comparison
Time : 14:45-15:10
Biography:
Mandeep Sekhon has completed his PhD in Mechanical Engineering from University of Victoria, BC, Canada and is currently working as a Post-doctoral Researcher at UC, Merced, CA, USA. He did his Master’s in Energy studies from Indian Institute of Technology, Delhi. His research interest is in the field of Thermo-Fluids and Energy. He is working in the area of numerical simulation of crystal growth and other material processing technologies.
Abstract:
Liquid phase diffusion (LPD) is a solution growth technique that has been used to grow SixGe1-x single crystals. An integrated top level solver has been developed in an open source code OpenFOAM to simulate the initial melting and subsequent solidification process during LPD growth. The initial melting process is modeled using the well-known enthalpy-porosity technique while the solidification is simulated using a model originally developed to model dendritic alloy solidification. Initial melting is modeled in order to compute the shape of the initial growth interface along with temperature and concentration distribution. This information is then used by the solidification solver which in turn predicts the onset of solidification, evolution of the growth interface, and temperature and concentration fields as the solidification proceeds. The results are compared with the previous numerical study conducted using the dynamic grid approach as well as with the earth based experimental results. In the second part of the talk, the simulation of LPD using dynamic grid will be discussed. The implementation has been carried out in commercial code Ansys Fluent software by developing special user defined functions. Finally, a comparison between the two approaches and their relative advantages and disadvantages shall be presented.
Srikanth Patala
North Carolina State University, USA
Title: Algorithms for generating coincidence site lattices (CSLs) and near-CSLs in arbitrary bravais lattice systems
Biography:
Srikanth Patala received his B.Tech. in metallurgical and materials engineering from the Indian Institute of Technology Madras in 2005 and his PhD in materials science and engineering from the Massachusetts Institute of Technology in 2011. Prior to joining the NC State faculty in 2013, he was a postdoctoral researcher in the Department of Materials Science and Engineering at Northwestern University. Patala’s research will be focused on developing computational and analytical techniques to quantify the structure-property relationships in complex heterogeneous materials.
Abstract:
The formulation of Coincidence Site Lattices (CSLs) has played a fundamental role in the analysis of interfaces in both experiments and simulations of inorganic materials systems. For example, the prediction of habit planes during precipitation and phase transformations relies on the determination of near-CSLs between the parent and the product lattice. The distributions of internal interfaces are generally analyzed as a function of their corresponding Σ-misorientations. Therefore, the ability, to automatically generate the Σ-rotations and their corresponding CSLs will not only enable the high-throughput prediction of interface structure-property relationships but will also help understand microstructure evolution during phase transformations. Grimmer, in a series of articles, has proposed the generating functions for determining the coincidence site lattices for cubic, hexagonal, trigonal and tetragonal Bravais lattices. These generating routines increase in complexity as the underlying symmetry of the lattice is reduced. In this talk, I will present a simple algorithm that computes all the unique CSL generating rotations for any Σ, and in arbitrary Bravais lattice systems. The algorithm involves two simple steps: (i) determination of all the unique sub-lattices of volume Σ, and (ii) the computation all the unique pairs of sub-lattices that are not related by the symmetry operations of the underlying crystals. I will also present strategies for extending this algorithm for computing near-CSL rotations between any two Bravais lattice systems (i.e. both homo-phase and hetero-phase interfaces).
Christian BONHOMME
Pierre et Marie Curie University, France
Title: NMR Crystallography: When nuclear magnetic resonance and diffraction meet
Biography:
Christian BONHOMME has completed his PhD at the age of 27 years from Pierre et Marie Curie University (UPMC) in Paris, France. Currently, he is full Professor at UPMC. He has been Invited Professor at the Department of Physics, Warwick University, UK. He is the leader of the SMiLES group at the Laboratoire de Chimie de la Matière Condensée de Paris. He has published more than 105 papers in reputed journals and has given 50 invited conferences in the fields of NMR, NMR Crystallography and Materials Science.
Abstract:
This presentation will expose an overview and the latest methodological developments in NMR Crystallography. Such a concept appeared recently in the solid state NMR community following the pioneering work of Pickard and Mauri (Phys. Rev. B, 2001) and their implementation of the GIPAW method. Such a method allows the calculations of NMR parameters from first principles (at the DFT level) under periodic boundary conditions. Such calculations lead to full NMR tensorial parameters for all interactions (chemical shift, quadrupolar, J coupling, Knight shift) and for all nuclei described in the asymmetric unit of the crystal. GIAPW has been also extended to amorphous and disordered derivatives [1]. The complementarity of diffraction techniques (X-rays and neutrons) and solid state NMR will be presented in the frame of NMR Crystallography. The goal of this approach is to propose new perspectives for the refinement of structures. The following questions will be raised: are NMR parameters sufficient for a full description of a crystal structure? Are a limited number of chemical environment representative of glassy architecture? A large panel of examples will illustrate the NMR Crystallography concept: inorganic structures, organic/inorganic hybrids, disordered materials such as biocompatible glasses doped with various cations. Applications of GIPAW will be presented as well in the frame of EPR and other spectroscopies. [1] C. Bonhomme et al., Chemical Reviews, 112, 2012, 5733-5779.
Biography:
Akwasi Asamoah started his PhD at the age of 35 years at University of Exeter and Mphil and Bsc studies at the Kwame Nkrumah University of Science and Technology. He is interested in Materials and Structures for Defence and Security Applications. He has published more than 30 papers in journals, proceedings, compendia, books and reports and serves as a reviewer of several thriving journals. 

Abstract:
The 1D bundles of cellulose microfibrils (lignified flax fibre) and 2D networks of cellulose microfibrils form tunicate, bacterial and microfibrillated celluloses were strained in tension, and their molecular deformation followed by Raman spectroscopy in order to fully understand the origins and magnitudes of in-plane auxetics for the information of innovation. Cellulose is found to exhibit three distinct yielding. Both crystalline and amorphous cellulose are found to be auxetic so long as intermolecular hydrogen bonding remain intact. Auxetics of crystalline cellulose is found to be around unity (-1) while that of cellulose amorphous is found to be around twice (-2) that of crystalline cellulose with the possibility of 1D bundles of cellulose microfibrils registering auxetics higher than -7 in the absence of lignin. Though 2D networks of cellulose microfibrils enhance strain to failure, they also significantly limit auxetics of single 1D cellulose microfibrils in networks. Differences in auxetics between crystals and amorphous must predominantly arise from differences in intermolecular geometry. Similarity of in-plane auxetics of cellulose to the off-axis auxetics of zeolites (especially thomsonite zeolites) indicates the possibility of combining both semi-crystalline materials to produce functionalized composites with photo-electromechanical properties.
Anit Joseph
Leibniz University, Germany
Title: Synthesis of gadolinium oxynitride layer on Si by nitrogen ion implantation
Biography:
Anit Joseph is now doing her PhD in leibniz university hannover, germany. She is awarded for hannover school of nanotechnology(HSN) PhD fellowship for 3 years.She is from india. She completed her bachelors and masters in Electronics. Now working in the Institute of electronic materials and devices and focussing on Gadolinium oxide materials ,epitaxial growth and oxynitrides .
Abstract:
As the scaling laws become less effective in boosting the performance of CMOS technology for 90 nm node and beyond, high dielectric constant(high-k) materials have attracted a great deal of interest to meet the formidable challenges for replacing the conventional silicon dioxide(SiO2) or silicon oxynitride gate insulators. Transition metal oxides and rare earth metal oxides , especially Gd2O3(Gadolinium Oxide), are now considered as the promising candidates for the next generation dielectrics. However, there are some fundamental problems associated with these high-k metal oxides. The thermal instability, poor interface with silicon, high oxide trap and interface trap densities and large leakage current become the major concerns. Recent studies demonstrated the the incorporation of nitrogen into high-k dielectric film or at the high-k dielectric interface with the Si substrate could be quite effective in suppressing crystallization of metal oxide,decreasing dopant penetration into bulk Si, inhibiting interfacial reaction with the Si substrate, and also improving both the material and electrical performance of the devices. This work reports on the formation of Gadolinium oxynitride layer by nitrogen ion implantation method.
Andriy Lotnyk
Leibniz Institute of Surface Modification (IOM), Germany
Title: Local atomic arrangement in Ge-Sb-Te phase-change thin films
Biography:
Andriy Lotnyk has completed his PhD in 2007 from the University of Halle working at the Max Planck Institute of Macrostructure Physics (Halle) and postdoctoral studies from the same Institute. He has been a permanent staff member at the Faculty of Engineering, CAU of Kiel in 2009-2011. Presently, he is a group leader of the group “Structure Determination and Electron Microscopy” at the Leibniz Institute of Surface Modification (IOM). Dr. Lotnyk was awarded by the Otto Hahn Medal from the Max Planck Society in 2008. He has authored and co-authored more than 50 scientific publications in per-reviewed journals and about the same number of conference papers.
Abstract:
Phase change materials (PCM), such as Te-based Ge2Sb2Te5 (GST), are known from optical memory applications and can be also used in non-volatile next generation random access memory. The relevant phases of GST are an amorphous phase, a metastable cubic rock salt like structure and a stable hexagonal layered structure. However, the atomic arrangements in the GST lattices are not well-understood and still under discussion. Insights into the local atomic arrangement of layered Ge-Sb-Te compounds are of particular importance from a fundamental point of view as well as for optical and electronic applications such as data storage, thermoelectric and ferroelectric. In this work, the local atomic arrangement in metastable GST and in Ge-Sb-Te thin films consisting of GST, Ge1Sb2Te4 and Ge3Sb2Te6 layered crystal structures are studied by using a combination of atomic-resolution aberration-corrected (Cs-corrected) high-angle annular dark-filed scanning transmission electron microscopy (HAADF-STEM) and detailed theoretical image simulation approaches. By comprehensive analyses of experimental and simulated HAADF-STEM image intensities, a structural model for metastable Ge2Sb2Te5 is proposed. In addition, the proper stacking sequences in the Ge-Sb-Te phases are determined. The obtained data are discussed with respect to existing experimental and theoretical structure models reported for bulk Ge-Sb-Te materials.
Melanie John
Ludwig-Maximilians-Universität München, Germany
Title: Synthesis of (doped) ABO2 nanoparticles: Can this work at temperatures ≤ 90 °C without using an additional reducing agent?
Biography:
Melanie John received her B.Sc. in Earth Sciences in 2012. She continued her studies in Geomaterials and finalized her M.Sc. in 2014. Within 2 years, she performed her PhD studies. She developed an environmental sustainable concept to extract heavy metals from aqueous solutions. At the same time, she created a new method to synthesize nanoparticles as delafossite and special core-shell composite materials at low temperatures < 90 C. Now she is continuing to widen her interdisciplinary research field. She published papers in reputed journals of both research fields, solid-state chemistry as well as in environmental science and technology
Abstract:
Delafossite (ABO2) is in focus of extensive research for its special magnetic, photo- and electrochemical as well as antiviral properties. Delafossite structures show a wide variability of chemistry (A = e.g. Cu, Ag and B = e.g. Fe, Mn, Cr, Co, Al) and are used for diverse technical applications including catalysis, p-type conduction oxide, solar cells, or as luminescent material. Many physical properties are directly related to grain size, but most of the common synthesis routes as solid-state reactions, sol-gel or hydrothermal techniques lead to crystals in micron size. With the Lt-delafossite process, a new synthesis route by precipitation and subsequent ageing, it is possible to gain pure nano-sized delafossite at temperatures ≤ 90 °C. The synthesized product exclusively consist of hexagonal, platy crystals with a diameter of less than 500 nm. The thickness increases with increasing ageing time from 5 to 200 nm. In case of CuFeO2, green rust (GR), precipitates first. Additional supply of OH- leads to the transformation of GR to delafossite. At the same time, GR acts as reducing agent for Cu2+. The ratio of 3R and 2H polytype is directly controllable by e.g. NaOH supply. The magnetic properties of CuFeO2 prepared by Lt-delafossite process deviate from both, natural delafossite and samples synthesized by other routes. A new approach is to produce doped delafossite. However, the incorporation of foreign ions is limited. Partly they are adsorbed on the surface and so hinder crystal growth especially in [001]. Moreover it promotes twinning of the crystals.
Biography:
Seham K Abdel-Aal, has completed her PhD from Cairo University, Egypt, one of the top ten Universities in Africa and middle east, and post doctoral studies from AMU University the 2nd University in India, she is author of 4 books related to preparation, crystal structure, properties of new hybrid materials as well as several papers in peer review journals. She participated in several conferences all over the world. She deposited 9 cif files, new crystal structure in Cambridge crystallographic data center CCDC. She awarded from International Union of Crystallography IUCr to attend the 1st Eropean School on crystal growth ESCG Bologna Italy.
Abstract:
Crystal structure of series of organic-inorganic hybrid of the formula [NH3(CH2)nNH3]CoX4, n = 3 - 9, X = Cl, Br, consists of organic dications [NH3(CH2)nNH3]2+ act as spacer between inorganic dianions CoII coordinated by four halogen atoms in an isolated tetrahedral structure [CoX4]2-. The organic and inorganic layers form infinite 2D sheets parallel to ac plane and are connected by N-H….X hydrogen bonds. Blue single crystals were grown from ethanolic solution in 1:1 stiometric ratio (organic / inorganic) by slow evaporation and gradual cooling to room temperature. The hybrid crystallizes in a triclinic system, space group P¯1, centrosymetric, the unit cell parameters are provided. The lamellar structure of Co- perovskite hybrid is typically as naturally self assembled multiple quantum wells MQW. The organic chains acts as barriers and the cobalt halide ion act as wells. The calculated lattice potential energy Upot (kJ/mol) and lattice enthalpy ΔHL (kJ/mol) are inversely proportional to the molecular volume Vm (nm3) of perovskite hybrid of the formula [NH3(CH2)nNH3]CoCl4, n = 3 - 9. thermal properties and phase transition of [NH3(CH2)7NH3]CoBr4-xClx (x = 0, 2, 4) are provided. The cif file of the complete crystallographic data including unit cell parameters, bond distances, bond angles and hydrogen bond geometry of NH3(CH2)4NH3 CoCl4, NH3(CH2)7NH3 CoCl4, NH3 (CH2)7 NH3CoBr4, and NH3(CH2)9NH3CoCl4 will discuss.
Zuzana POKORNA
Institute of Scientific Instruments of the Czech Academy of Sciences v.v.i., Czech Republic
Title: Scanning very low energy electron microscopy as a tool for obtaining crystallography-related information from single crystal and polycrystalline metals
Biography:
Zuzana Pokorna has completed her PhD from Masaryk University at the Institute of Scientific Instruments of the Czech Academy of Sciences. She won the prize for Best Doctoral Thesis Using Microscopical Methods bestowed by the Czech and Slovak Microscopical Society in 2013 with her PhD thesis employing the Scanning Low Energy Electron Microscopy. She works in the group of dr. Ilona Mullerova who was awarded the national Scientific Inventiveness prize for the development of this method. Acknowledgment This research has been financially supported by a TACR grant no. TE01020118 (EC grant FP7 606988 SIMDALEE2, Strategie AV21 ???) References [1] Mullerova, I., & Frank, L. (2003). Scanning low-energy electron microscopy. Advances in imaging and electron physics, 128, 310-445. [2] Bauer, E. (1998). LEEM basics. Surface Review and Letters, 5(06), 1275-1286. [3] Pokorná, Z., et al. "Characterization of the local crystallinity via reflectance of very slow electrons." Applied Physics Letters 100.26 (2012): 261602.
Abstract:
Scanning Low Energy Electron Microscopy (SLEEM) is a Scanning Electron Microscopy technique that allows using arbitrarily low electron energies while preserving a very good image resolution [1]. Reflectivity of very low energy electrons in the range 0–30 eV correlates with the electronic structure of the material [2]. This may be used for the determination of specimen crystallographic orientation. As the incident electron energy is changed in the 0–30 eV energy range, the image signal of reflected electrons undergoes variations. Regions of different crystallographic orientation exhibit different reflectivity behavior [3]. This is enhanced partly also because of larger-angle contributions of the signal that are very efficiently collected by this technique. The experiments were performed on ultra-clean single crystal and polycrystalline metal specimens in ultra-high vacuum conditions. Fig. 1 shows an example of how differently oriented grains differ in reflectivity. From the experiment, the function of image signal vs. incident electron energy was determined. This was further processed via advanced numerical algorithms, allowing visualization of areas with different crystallographic orientation of an arbitrary grain. The results were verified by EBSD and compared to electron optical simulations helping to elucidate the non-trivial task of signal collection.
Biography:
Åžerife YALÇIN has completed her PhD at the age of 29 years from Erciyes University and postdoctoral studies from Caen University. She has published more than 25 papers in reputed journals and has been serving as an editorial board member of repute.
Abstract:
Developments in science and technology have required the production of new materials and design. Knowing the properties of the materials used for obtain them is helpful to design and manufacture of materials that we need. Crystallography is the science of structure used to characterization of materials and determine of some physical properties with texture analyses. It includes the general features of structure and deals with the mapping of all kinds of systems as geometrical representations. The same material with different crystallographic parameter has different properties. It is hardly possible to develop materials science without crystallographic techniques
W.-Z. Zhang
Tsinghua University School of Materials Science and Engineering, China
Title: Identification of Singular interfaces with ï€ ï„g vectors
Biography:
Wenzheng Zhang has completed her PhD in 1991 from McMaster University, Canada. She joined the Department of Materials Science and Engineering in Tsinghua in 1997, and has been full professor since 1999. She has published more than 100 peer reviewed papers and given a number of invited and contributed presentations. She has been serving as a key reader for Metallurgical and Materials Transactions A and an editorial committee member of Acta Metallurgica Sinica.
Abstract:
Microstructures generated from solid state phase transformations often display a self-resemble morphology characterized with faceted interfaces of unique crystallographic orientations. Being stable in the transformation condition, the reproducible facets are likely singular interfaces, associated with singularity in the interfacial energy. This singularity is believed to be also associated with singularity in the interfacial structures. The structure of a singular interface must consist of certain kind of low energy building blocks in major area, but existence of limited defects is possible. One may identify a singular interface based on elimination of interfacial defects, either ledges or dislocations. Based on elimination of ledges, a typical singular interface is atomic flat, which is usually normal to a low index reciprocal vector, g. Based on elimination of dislocations, an ideal singular interface is free of any dislocations, but these interfaces are rare. A singular interface can be identified according to elimination of at least one type of dislocations which must exist in any vicinal interface. Such a singular interface must be normal to one or more reciprocal vectors, ï„g, connected to gï¡ and gï¢, of the two phases (ï„g = gï¡ ï€ gï¢). It is simple to elucidate the puzzling high index orientation of a facet with ï„g, since ï„g may not be parallel to any low index gï¡ or gï¢. The reason behind the ï„g approach is mainly based on the O-lattice theory. This will be explained in presentation together with examples from various materials to demonstrate the applications of this approach.
Fen Xu
Guilin University of Electronic Technology, China
Title: Studies on synthesis and adsorption/Thermodynamics of metal organic frameworks
Biography:
Fen XU has completed his PhD in 2005 from Dalian Institute of Chemical Physics, Chinese Academy of sciences. She is the Professor of School of Material Science and Engineering, Guilin University of Electronic Technology. She has published more than 70 papers in reputed journals and has been serving as a referee for Biosensors & Bioelectronics, Thermal Analysis & Calorimetry, etc..
Abstract:
Based on the theory of crystal engineering, the MIL-53(Al-Cr) with mixed cations was successfully synthesized by selecting the optimal synthesis conditions and molar ratio of Al and Cr salts. The breathing effect of MIL-53(Al-Cr) was studied by the X-ray thermodiffractogram. The porous structure of MIL-53(Al-Cr) was also obtained, which is different from that of MIL-53(Al) or MIL-53(Cr). The applications of MIL-53(Al-Cr) in the CO2 and VOCs adsorption were studied. The results indicated that the CO2 uptake of the MIL-53(Al-Cr) increased by 15% and 14% than MIL-53(Al) and MIL-53(Cr), respectively. Furthermore, the MIL-53(Al-Cr) easily adsorbed aniline in the mixed solution of aniline and phenol. The MIL-53(Al-Cr) is a proming material for CO2 and VOCs adsorption. The thermodynamic properties of Co(3,5-PDC)(H2O) and Al(NDC) were studied by using the temperature modulated differential scanning calorimetry (TMDSC). . Acknowledgements: The authors wish to acknowledge the financial support from the National Natural Science Foundation of China (U1501242, 21403267, 21373215, 51361005, 51371060, 51201042, 51461010 and 51201041), Guangxi Natural Science Foundation (2014GXNSFAA118319, 2014GXNSFDA118005), Guangxi Key Laboratory of Information Materials (161002-Z) and Guangxi Scientific Technology Team (2012GXNSFGA06002, 2015GXNSFFA139002).
Li-Xian Sun
Guilin University of Electronic Technology, China
Title: Synthesis and applications of porous materials for gas storage
Biography:
Li-Xian SUN has completed his PhD in 1994 from Hunan University and postdoctoral studies from Jena University supported by Alexander von Humboldt Fellowship and from National Institute of Advanced Industrial Science and Technology by NEDO fellowship. He is the Dean of School of Material Science and Engineering, Guilin University of Electronic Technology, Fellow of RSC (FRSC), Counsellor of International Association of Chemical Thermodynamics (IACT), Vice Chairman of of committee on Chemical Thermodynamics and Thermal Analysis of Chinese Chemical Society. He has published more than 300 papers in reputed journals and has been serving as a regional editorial board member of Thermal Analysis & Calorimetry.
Abstract:
Studies of economic, highly efficient and safe gas storage materials (GSMs) are of great importance in the fuel cells based vehicles and CO2 capture. In our lab., we focus on studies on GSMs for H2 and CO2 based one micro/nano-technology. A series of metal organic frameworks (MOFs) and porous carbon materials such as grapheme for GSMs were synthesized. Their crystal structures, gas storage and thermodynamic properties were systematicall evaluated. Furthermore, relationship of structure – activity were explored. Acknowledgements: The authors wish to acknowledge the financial support from the National Natural Science Foundation of China (U1501242, 21403267, 21373215, 51361005, 51371060, 51201042, 51461010 and 51201041), Guangxi Natural Science Foundation (2014GXNSFAA118319, 2014GXNSFDA118005), Guangxi Key Laboratory of Information Materials (161002-Z) and Guangxi Scientific Technology Team (2012GXNSFGA06002, 2015GXNSFFA139002). References [1] Z. Wang, L. Sun, F. Xu, et al.. Rsc Advances, 6 (2016) 1422-1427 [2] S. Liu, L. X. Sun,s, et al., Energy & Environmental Science, 6(2013)818-823.
Manojkumar N. Parmar
The H.N.S.B.Ltd.Science College, India
Title: Transport property measurements on tungsten diselenide single crystals doped by copper
Biography:
Dr. Manojkumar N. Parmar has completed his PhD at the 38 years from S.P.University, Anand,Gujarat-India of solid state physics. He is the associate professor and head of the physics department in The H.N.S.B.Ltd. Science College, Himatnagar. He has published more than 22 papers in reputed journals.
Abstract:
The electronic industry needs high quality semiconductor materials in order to realize devices in situations where standard silicon chips cannot work due to expense and geometry. Poor mobility of organic materials has led to the search of new inorganic alternatives i.e. transition metal dichlcogenides. These TX2 (T=Transition metal, X=Chalcogen) are used in diverse applications as catalysts, batteries, lubricants and in fabrication of photoelectrochemical solar cell etc. In light of this realization the present paper reports on the growth of copper doped tungsten diselenide single crystals i.e. CuxWSe2 (x=0, 0.5, 1.0) by direct reaction of the elements using direct vapour transport technique. Transport properties viz. low and high temperature resistivity measurements, high pressure are studied in detail on all these samples. The results obtained and their implications will be discussed in the paper in depth.
Rajni Kant
University of Jammu, India
Title: Crystallographic and molecular packing interaction analysis of cholest-based steroids: A CSD study
Biography:
Rajni Kant completed his Ph.D from University of Jammu (India) in 1989 and Post-Ph.D from Oxford University (U.K) during 1994-95. Presently he is Professor of Physics at University of Jammu and also the Editor-in-Chief for Open Journal of Inorganic Chemistry (Scirp, USA). He has guided 21 Ph.D students, 48 M.Phil students and has published over 350 research papers in journals of international repute.He has authored a book titled “Applied Solid State Physics”, published by WILEY-INDIA Ltd.
Abstract:
Biological activity of steroids is one of the most important reasons for their synthesis and structural characterization. Cholestane (C27H48), the parent compound of all steroids, is obtained by the removal of hydroxyl group (from C3 position) and reduction of double bond (between C5 and C6 atoms) from the basic cholesterol nucleus. A total number of twenty-three structures of cholestane derivatives were obtained from the CSD for a comparative analysis of their crystallographic structures, computation of their possible biological activities and molecular packing interaction analysis. Intermolecular interactions of the type X-H…A [X=C,O, N; A=O, Cl, N, Br, F] have been analysed for a better understanding of molecular packing in cholestane class of steroids and discussed on the basis of distance-angle scatter plots. A careful examination of the entire interaction data reveals that the C-H…O hydrogen bonding is quite predominant in cholestane derivatives. The nature of the substituent at C3 position of the cholestane nucleus makes these molecules very interesting candidates for hydrogen bonding analysis. In most of the cases, the substituent at C3 position is primarily responsible for the occurrence of intermolecular hydrogen bonding in cholestanes. These substitutions are linked by intermolecular hydrogen bonding which in turn help to understand the dynamics of stacking interactions in supramolecular structures. Similar studies have also been carried out on various other classes of Cholest-based steroids, viz. Cholane, Pregnane, etc., to look for a possible solution to some of the following queries: (i) Could structural diversity in steroids be explored for a generalized crystallographic co-relations? (ii) Which of the X-H...A interactions (intra- or intermolecular) are dominant in various classes of steroids? (iii) Is there any preference of linearity for different hydrogen bonded interactions? Results of the emperical analysis of various kinds of cholest-based steroids as picked up from the CSD shall be presented.
K. Ramachandra Rao
Crystal Growth and Nano Science Research Centre, India
Title: Structural and optical studies on rare earth doped L-Histidine hydrochloride mono hydrate single crystals
Biography:
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Abstract:
Bulk growth nonlinear optical single crystals of Eu3+ ion doped L-Histidine hydrochloride monohydrate (LHHC) have been grown using slow evaporation method (SEST) and also Sankaranarayanan-Ramasamy (SR) uniaxial crystal growth method from aqueous solution. The lattice dimensions have been measured from the single crystal X-ray diffraction analysis and belong to orthorhombic system having non-Centro symmetry with P212121 space group. The crystalline perfection has been evaluated by high resolution X-ray diffraction (HRXRD) technique and found that the crystalline quality is good. The Presence of various functional groups has been identified through Fourier transform infra-red spectroscopy (FTIR). Its optical character has been assessed by UV-Vis analysis and found to be transparent with its lower cut off wavelength 242nm. Eu3+: LHHC crystal has 9% higher transmittance than that of pure sample. The optical band gaps of Eu3+ doped samples grown by SEST and SR methods were observed 4.3 eV and 4.4 eV respectively. The thermal analysis (TG/DTA) of the grown crystal indicated the better thermal stability and was thermally stable up to 156 0C. Surface morphology of the growth plane was observed by using scanning electron microscopy (SEM).The elemental analysis and the incorporation of Eu3+ ion in the crystal lattice was confirmed using energy dispersive X-ray analysis (EDAX). The dielectric constant was higher and the dielectric loss was less in the grown crystals. Frequency dependent dielectric constant and dielectric loss of the grown crystals were carried out along the growth axis for different temperatures. The mechanical strength of the grown crystals was tested by Vickers micro hardness study along the growth plane (100) and the crystals grown by SR method have higher hardness value than SEST grown crystal. SHG efficiency of the grown crystal was observed 3.6 times higher than that of potassium dihydrogen phosphate (KDP) single crystal. The photoluminescence (PL) study of the crystal was investigated using spectro photometer at room temperature. The grown crystal was excited by 615 nm wavelength. The emission spectra of the crystal excited with ultraviolet radiation shows that the intensity of 5D0→7F2 emission is stronger than 5D0→7F1 emission of Eu3+.The decay of Eu3+: LHHC grown crystals is bi- exponential in nature with a long life time of ï´2 is 7.2410 µs. The photoconductivity study confirms the positive photo conducting nature of the grown crystal.
A.Kabir
Skikda University, Algeria
Title: Structural and morphological characterization of tin oxide films prepared by the RGTO method
Biography:
Abdenour KABIR has completed his PhD at the age of 30 years from Skikda University (Algeria) and postdoctoral studies from Skikda University in Algeria. He is a teacher in this University.He has published more than 5 papers in reputed journals and has been serving as a reviewer in journals of repute.
Abstract:
Tin oxide (SnO2) is a largely used material in different domains such as nanocrystalline photovoltaic cells and gas sensing. In this work, this material was deposited by the RGTO method (Rheotaxial Growth and Thermal Oxidation). This technique, which consists on the thermal oxidation of the Sn films deposited onto heated glass substrate at a temperature close to tin melting point (232°C), allows preparing high porosity tin oxide films. This films type is very suitable for the gas sensing. The films structural and morphological properties pre and post oxidation were studied using the x-ray diffraction (XRD) and the scanning electron microscopy (SEM) respectively. XRD patterns showed a polycrystalline structure of the cassiterite phase of SnO2. The grain size increased as a function of the oxidation time and tended to saturate. This grain size evolution was confronted to existing grain growth models in order to understand the growth mechanism. From SEM images, the as deposited Sn film was formed of difference diameter spherical agglomerations. As a function of the oxidation time, these spherical agglomerations size increased and their shape changed due to the introduction of oxygen ions. The deformed spheres started to interconnect by forming bridges between them. These bridges induced the decrease of the electrical resistivity
Jintaek Gong
Korea Advanced Institute Science and Technology, Republic of Korea
Title: Structure determination from powder diffraction data of self-assembled structures consisting of beta-peptide foldamers
Biography:
Jintaek Gong received his Bachelor of Science degree (Magna Cum Laude) in Chemistry in 2011 from the Korea Advanced Institute of Science and Technology (KAIST). He then went on to graduate school at KAIST during the same year. He is a student in the Integrated Masters & PhD Program in the Department of Chemistry at present. He has published seven papers in reputable journals and has served as a powder crystallographer in the Biomimetic Organic Laboratory of KAIST.
Abstract:
A well-designed beta-peptide foldamer can self-assemble to create various well-defined 3D architectures in aqueous solutions, named as foldecture. The term foldecture is combination of the words foldamer and architecture. Our group has reported unprecedented shapes of foldectures, such as a windmill and a molar tooth. These were highly homogenous both in terms of their size and morphology. Furthermore, to explore their potential use as functional materials, we recently published a study in which carboxyl groups were exposed to specific rhombic facets of foldectures. We found new potential capabilities of foldecture in relation to their mechanical properties as well, such as an anisotropic shape of a micro-sized container through the creation of a hollow cavity. Meanwhile, research on the functionalization of foldectures is expanding, as comprehending the self-assembly process and the resulting 3D shapes requires additional work. Hence, the structural determination of the molecular packing structure of foldecture is essential. In relation to this, the powder X-ray diffraction technique has been utilized here due to the dimensions and kinetical experimental conditions of foldecture. A PXRD analysis with synchrotron radiation was adequate to determine the packing structure with well-organized bonds and angle restraints. Further, it was able to designate the absolute orientation of the foldamers involved based on the predicted preferred orientation approximation. The use of a PXRD analysis on foldecture aided the understanding of the shape and properties of the newly formed foldecture and can be expected to play a major role in designing original examples of foldecture in the future.
Myobin Jeon
Korea Advanced Institute Science and Technology, Republic of Korea
Title: Surfactant-mediated shape evolution of 3D organic molecular architecture
Biography:
Myobin Jeon received Bachelor of Science degree (Summa Cum Laude) in Chemistry in 2014 from Pusan National University (PNU). She then went to graduate schools at KAIST in the same year. She is a student in the Intergrated Master’s & Ph.D Program at the Department of Chemitry to date.
Abstract:
Systematic studies of the mechanism of the surfactant-controlled self-assembly of organic molecules are challenging in the field of crystal engineering and nanotechnology. Here, we discuss the shape evolution of three-dimensional molecular architectures (foldectures) formed from the self-assembly of a ï¢-peptide foldamer. The evolution of the shape from a square plate to a square pyramid was observed, and the molecular packing structure was analyzed by diffraction experiments. This shape evolution arises from the passivation of the surfactants on the crystal facets and synergistic effect of their counterions. Moreover, we performed surface-energy calculations through a molecular dynamics simulation to demonstrate the roles of additives in the crystal growth mechanism. These findings would bolster our understanding of the interactions between surfactants and the interfaces of organic molecules and thus provide deeper insight into the design of functional organic materials.
- Track 1:Advanced Crystallography
Track 7: Crystallography Applications
Location: Houston
Session Introduction
Victor Ovcharenko
International Tomography Center, Russia
Title: Breathing crystals - P,T-Induced dynamics of heterospin crystals
Biography:
Victor Ovcharenko is the Head of Multispin Coordination Compounds Laboratory at the International Tomography Centre. He has published more than 200 papers in reputed journals (coordination chemistry of free radicals, design of molecular magnets, spin transitions).
Abstract:
The results of studies of magnetostructural correlations inherent in heterospin coordination compounds of transition metals with stable nitroxides were discussed. When the temperature changes, the compounds undergo structural rearrangements accompanied by magnetic effects similar to spin crossover. The magnetic effects that appear as a result of the structural rearrangement of the crystal are determined by the spatial dynamics of the coordination units containing exchange clusters {Jahn-Teller metal ion–coordinated organic radical} and generally involve considerable changes in the crystal volume during repeated cooling-heating cycles. Mechanical stability of heterospin crystals capable of being reversibly compressed and expanded during multiple crossing of the temperature range of the phase transition region is reflected by the term "breathing crystals." The plasticity of the single crystals allows studies of reversible SC–SC phase transformations over a wide temperature range (30–300 K), the creation of X-ray cinema, and analysis of structural transformations in the four-dimensional space (coordinates + temperature). The report discusses methods of control over the character and temperature of spin transition for compounds from this class. The effect of a change in the external pressure on the character of the temperature dependence of the effective magnetic moment was also discussed. The phase transformation of the heterospin compound caused by its cooling may be accompanied by deep coloring of the solid phase, which is an unusual effect. The possibility of creating spin devices whose working mechanism (unit) is an exchange cluster that changes multiplicity under the action of temperature, pressure, or light was discussed.
Yanli Wang
Chinese Academy of Sciences, China
Title: Structure-based mechanistic insights into PAM-dependent spacer acquisition for incorporation into the CRISPR array
Biography:
Yanli Wang has completed her PhD fromUniversity of Science and Technology of China and postdoctoral studies from Memorial Sloan-Kettering Cancer Center. She is a principle investigator of Institute of Biophysics, Chinese Academy of Sciences. She has published more than 25 papers in reputed journals and has been serving as an editorial board member of Non-Coding RNA.
Abstract:
Bacteria obtain a memory of viral invaders by incorporating their DNA sequence elements into the host CRISPR locus, generating a new 33-nt spacer within the CRISPR array. We report on the crystal structure of a Cas1-Cas2-dual-forked DNA complex in efforts towards understanding how the protospacer is selected for insertion into the CRISPR locus. Our structure of the complex reveals a protospacer DNA containing a 23-bp duplex bracketed by tyrosine residues, together with anchored flanking 3’-overhang segments. The complementary PAM sequence in the 3’-overhangs are recognized by Cas1a catalytic subunits in a base-specific manner for protospacer selection and subsequent cleavage at positions 5-nts from the duplex boundary, thereby generating a 33-nt DNA intermediate for incorporation into the CRISPR array. Upon protospacer binding, the Cas1-Cas2 complex undergoes a significant conformational change, generating a flat surface conducive to proper protospacer recognition. Overall, our studies reveal unanticipated structure-based mechanistic insights into PAM-dependent spacer acquisition.
Geeta Hundal
Guru Nanak Dev University, India
Title: Hydrated nickel(II) ions- the new secondary building units for the formation of 2D and 3D cationic water networks
Biography:
GH has done her Ph. D from Guru Nanak Dev University in the field of small molecule crystallography. She did her post doctoral research for two years in the same field at CSIC, Rocasolano, Madrid, Spain and stayed in South Korea for two years as Brain-pool scientist in the Korean Research Institute of Chemical Technology She is presently a professor in the department of Chemistry, Guru Nanak Dev University, Amritsar, India. She has published 145 research papers in journals of international repute. Besides crystallography her other interesst are chemical sensing, supramolecular chemistry and coordination chemistry.
Abstract:
As supramolecular assemblies, water molecules may just act as fillers by accommodating the interstitial voids or be a part of the self-assembled architecture themselves. The inter- and intramolecular H-bonds in various water clusters have been found to lie between −9 and −32 kJ mol−1 and −10 to −100 kJ mol−1, respectively, and for both, the data invariably depends on the O···O cutoff being considered. Therefore, the major role to understanding water cluster chemistry is played by X-ray crystallography.One of the aims of these structural studies on water clusters has been to accurately characterize them as various structural motifs. We have found that [Ni(H2O)6]2+ has the ability to form self-assembled supramolecular structures with lattice water molecules and demonstrate yet another unique modes of the cooperative association of water molecules, forming 2D and 3D cationic layers of water molecules. The anions are forming either alternate H-bonded layers with the 2D water layers or are sitting in the huge channels present in the open 3D network of water molecules. Such structural studies are helpful in understanding the nature and role of various water clusters in biological systems, where assorted metal ions are involved in diverse biological functions in an aqueous environment.
A. Thalal
Cadi Ayyad University, Morocco
Title: Symmetry in art and architecture of the western islamic golden age
Biography:
Abdelmalek THALAL completed his doctorate at the age of 31 years from Pierre and Marie Curie University (Paris) and Postdoctoral Studies from the Centre for Nuclear Energy (Grenoble). He obtained the PhD Prize awarded by the French National Centre for Scientific Research. He is professor of physics at the University Cadi Ayyad (Marrakech) and leads the research group "application of crystallography to the Moroccan geometric art". He has published over 25 articles and organized more than ten international meetings among which the European Crystallographic Meeting (Marrakech - 2007). He was member of several international scientific committees, leaded the project of the International Year of Crystallography (2014) and co-organized the closing IYCr2014.
Abstract:
Throughout history there were always links between geometry and art. These links become especially evident when to the study of ornamental art, we apply the theory of symmetry. The idea to study ornaments of different cultures from the point of view of the theory of symmetry, given by G. Pólya (1924) and A. Speiser (1927), was supported by the intensive development of the theory of symmetry in the 20th century. This work is dedicated to the symmetry in the ornamental art of the western Islamic. Moorish craftsmen developed an original, rich and varied art, which integrated the geometry in the construction of complex patterns. This art which flourished in Andalusia until the 15th century and continues to develop until now in North Africa, has evolved over the centuries involving symmetry in its most general sense: harmony, order, consistency and invariance. The ornamental periodic motifs that adorn buildings which will be discussed, from the standpoint of the theory of symmetry, existed long before Fedorov (1891), showed that there are only 17 periodic tilings of the plane. In the other hand, quasiperiodic tiling discovered by D. Shechtman (1984), adorn the ancient building in the western Islamic world. The similarity between the patterns and quasicrystals, aroused the interest of several crystallographers. Some examples of quasiperiodic patterns found in several Moroccan historical building will be described in term of Penrose tiling and give new quasiperiodic patterns obtained by Aboufadil et al using the multigrid method (2014).
Seyfan Kelil Shukri
Addis Abeba University, Ethiopia
Title: Charge transport properties in disordered organic semiconductor as a function of charge density: Monte carlo simulation
Biography:
Seyfan Kelil has completed his Msc at the age of 25 years from Addis Abeba University and Currently he is PhD student at Addis Abeba University. He is the lecture of Jigjiga University departement of physics
Abstract:
We have done Kinetic Monte Carlo (KMC) simulations to investigate the effect of charge carrier density on the electrical conductivity and carrier mobility in disordered organic semiconductors using a lattice model. The density of state (DOS) of the system are considered to be Gaussian and exponential. Our simulations reveal that the mobility of the charge carrier increases with charge carrier density for both DOSs. In contrast, the mobility of charge carriers decreases as the disorder increases. In addition the shape of the DOS has a significance effect on the charge transport properties as a function of density which are clearly seen. On the other hand, for the same distribution width and at low carrier density, the change occurred on the conductivity and mobility for a Gaussian DOS is more pronounced than that for the exponential DOS.
- Track 2: Crystallography in Biology
Location: Houston
Session Introduction
Lou Massa
Hunter College, & the Graduate Center CUNY, USA
Title: A new understanding in context of X-ray quantum crystallography (QCr) and the kernel energy method (KEM)
Biography:
Lou Massa has completed his PhD at Georgetown University and postdoctoral studies at the Brookhaven National Laboratory. He is the Director of the Laboratory for Quantum Crystallography at Hunter College and at the Graduate Center of the City University of New York, he is Professor of Chemistry & Physics. He has published more than 175 papers in reputed journals and has been serving as an editorial board member of Structural Chemistry (STUC).
Abstract:
We offer a new understanding, at once obvious and also of importance. KEM we suggest, if applied to Quantum Crystallography, implies a new field of study. For huge molecular systems this would allow description of biological interactions using abinitio quantum mechanical methodology. Crystallographic coordinates allow calculation of the complete Quantum Mechanics (QM) of crystallized biological molecules of any size. “Any size†envisions molecules of up to many hundreds of thousands of atoms in a biological complex. And, KEM has made this doable with any chemical model of any chosen accuracy. That is the new understanding within crystallography to which reference is made. We now recognize that KEM is capable of providing the entire quantum mechanics of crystallographic biological molecular systems. This because, given the X-ray structure the KEM formula delivers the energy E, and density matrices Ï2, Ï1, and the electron density Ï. The KEM formula, approximations to E, Ï2, Ï1, Ï, and the X-ray structure factors F(K) are expressed as follows: (1) (2) (3) (4) F(K) =  eiK.r{ } d3r (5) On the right side of all above equations the first sums are over double kernel quantities and the second sums are over single kernel quantities. The energy and the 3 density matrices above, of proven accuracy, are sufficient for the complete ground state quantum mechanics of any molecular system, including the X-ray structure factors. The complete quantum algorithm here suggested, is as follows: (1.) Recognize that the KEM formula delivers E , Ï2, Ï1, Ï and F(K); (2.) Given any crystal structure cut it into kernels; (3.) Calculate the kernels in the chemical model most appropriate to the accuracy needed; (4.) Calculate the full molecule energy E and the density matrices Ï2, Ï1, and Ï using the KEM formulas above; (5.) From the density matrices calculate any Quantum Mechanical property of interest for the whole molecule, including the –X-ray structure factors F(K). Note Well: No one has suggested extraction of the complete QM from crystallography as have we here.
Hélène Déméné
Structural Biochemistry Centre , UMR 5048 CNRS - INSERM - 1054 - UM1 UM2 , France
Title: Structural insights into the activation process of the opioid mu receptor
Biography:
Hélène Déméné has completed his PhD at the age of 26 years from Université Paris 6 and postdoctoral studies at the Mount Sinai Hospital (New York, US) and at the Institut de Biologie Structurale (Grenoble, France). She is now research associate at the Centre of Biochimie Structrale (Montpellier, France) where she specialized in the structural biology of GPCRs. She has published more than 25 papers in reputed journals.
Abstract:
Opioid receptors (OR), members of the G protein-coupled receptor (GPCR) superfamily, constitute the major target for the treatment of pain[1]. The use of opioid drugs acting at these receptors is however a leading cause of death by overdose in Europe and North America. Our collaborators recently described the structure of an antagonist-bound inactive and agonist-bound conformation of the µOR[2],[3]. It demonstrated the key molecular determinants for ligand binding and activation process common to other GPCRs. However, much remains to be learned about the mechanisms by which different agonists can induce distinct levels of Gi protein activation and/or arrestin recruitment upon activation of µOR. Pharmacological and biophysical studies suggest that this versatility can be achieved through the structural plasticity of GPCRs4. In this work, we analyze the conformational landscape of the µOR in distinct pharmacological conditions (full and partial agonists, antagonist) using liquid-state NMR spectroscopy in light of the X-Ray structures. We also investigate the structure and dynamics changes upon binding the effector Gs protein and a mimetic nanobody thereof. Our results show that there is very weak allosteric coupling between the agonist binding pocket and G protein coupling interface. Furthermore, the analysis provides clues on the successive structural events leading to the full active conformation of ïoR [5]. We know extend this approach to biased ligands, that are able to elicit G-protein activation without arrestin activation. A better knowledge of the structural basis of all activation pathways for opioid drug efficacy may lead to new therapeutic approaches with limited side effects. [1] Melnikova I (2010) Pain market. Nat. Rev. Drug Discov. 9(8):589-590. [2] Manglik A, et al. (2012) Crystal structure of the micro-opioid receptor bound to a morphinan antagonist. Nature 485(7398):321-326. [3] Huang, W, et al. Nature. 2015,524(7565):315-2 [4] Ghanouni P, et al. (2001) Functionally different agonists induce distinct conformations in the G protein coupling domain of the beta 2 adrenergic receptor. J. Biol. Chem. 276(27):24433-24436. [5] Sounier, R., et al. (2015) Nature 524, 375-378.
Nobuo Kamiya
Osaka City University, Japan
Title: Two alternative structures of oxygen-evolving complex in photosystem II found by X-ray crystallography at extremely low doses
Biography:
Nobuo Kamiya has completed his PhD at Nagoya University, Japan, and postdoctoral studies at Photon Factory (PF), High Energy Accelerator Research Organization (KEK). Researches on photosystem II have been started 30 years ago at RIKEN. He constructed structural biology beamlines at PF and SPring-8. At present, he is a professor of The OCU Advanced Research Institute for Natural Science and Technology (OCARINA), Osaka City University, and is continuing X-ray crystal structure analyses of proteins relating to photosynthesis.
Abstract:
Oxygen-evolving complex (OEC) is the heart of photosystem II (PSII), which extracts electrons from water molecules using solar light energy in photosynthesis. Crystal structure of PSII has been resolved at a resolution of 1.9 Ã… (Umena, Kawakami, Shen & Kamiya, Nature (2011)), and chemical formula of OEC is fixed as Mn4CaO5(H2O)4 for the first time. Based on the structural information (PDB-ID: 3WU2), researchers make efforts to elucidate the mechanism of oxygen-evolving reactions in OEC according to the Kok cycle model and to develop new catalysts for water splitting, which are required in artificial photosynthesis. Because OEC is highly sensitive to X-ray irradiation, however, X-ray reduction of OEC and structure changes induced have been discussed on the results from XAFS and DFT computational studies for the past five years. In order to overcome the X-ray reduction problem, we prepared highly isomorphous crystals of PSII and succeeded recently to collect two datasets of diffraction intensities at extremely low doses of 0.06 and 0.24 MGy (0.81 MGy for the previous dataset) at beamlins of SPring-8, BL38B1 and BL44XU. Obtained structures were compared with each other and with 3WU2, and two alternative structures of OEC were found in two monomers in an asymmetric unit of crystal. I will discuss in my talk about the meanings of the alternative structures and X-ray reduction effects on OEC.
Claudia Bravo-Chaucanés
University of BrasÃlia, Brazil
Title: Crystal structure of thioredoxin 1 from Cryptococcus neoformans at 1.8 angstroms resolution
Biography:
Claudia is a PhD student, completed her master in Molecular Biology at the Brasilia's university in 2014. She has participated in several national and international congresses and conferences. He has experience in the area of molecular biology, acting on issues such as cloning and gene expression, molecular biology of human pathogenic fungi, production of recombinant proteins, enzymatic assays, protein crystallography and in vitro testing of potential antifungal drugs.
Abstract:
Although fungal infections contribute substantially to human morbidity and mortality, the impact of these diseases on human health is not widely appreciated. Cryptococcosis is caused by Cryptococcus neoformans, an encapsulated fungus that causes lung disease and can spread widely in the brain and skin, affects about one million people each year and kills about 650,000. The virulence of this fungus is mediated by several factors, the antioxidant defense mechanisms have been shown to be important not only for resistance to reactive species but also for survival in the mammalian host. These antioxidant enzymes important for virulence may serve as excellent targets for antifungal therapy. The classical thioredoxin system is formed by thioredoxin reductase and its characteristic substrate the redox active protein thioredoxin, whose reduction is supported by NADPH. Thioredoxins are low molecular weight proteins that can be localized in the cytoplasm, in the mitochondria as well as in the extracellular space. Trx possess an active site made up of two cysteines in a conserved motif, CXXC, which is highly conserved. In this study, heterologous expression, purification, enzymatic characterization and crystallographic structure of oxidized Trx1 has been solved at 1.8Ã… resolution in the fungal pathogen C. neoformans. For crystallization assays, Trx1 has been concentrated to 9 mg mL-1 in 1,7 M Ammonium sulfate and 0,02 M Tris hydrochloride pH 8,5, the crystallization trials have been performed using the hanging-drop vapor diffusion method. X-ray diffraction data were collected using a synchrotron radiation source and the structure was solved by molecular replacement and refined to a crystallographic R factor of 15.0% and a free R factor of 19%.
Juliane Fonseca de Oliveira
University of Porto, Portugal
Title: Dimensionality of pattern formation in symmetric physical systems
Biography:
Juliane Oliveira has completed her B.S. in Mathematics from Federal University of Bahia (UFBA), Brazil, with final work related to studies of Einstein equation on Flag Manifolds. She is currently a PhD student in the Department of Mathematics at University of Porto, working in Bifurcation and Crystallography Theory. In particular, she wants to describe a mathematical tool in order to understand the transition of dimensionality in Reaction Diffusion systems in the Turing instability regime.
Abstract:
In the study of pattern formation in symmetric physical systems a 3-dimensional structure in thin domains is often modelled as 2-dimensional one. As a contrast, in this talk we use the full 3-dimensionality of the problem to give a theoretical interpretation and possibly decide whether the pattern seen in such systems naturally occur in either 2- or 3- dimension. For this purpose, we are concerned with functions in 3-dimention that are invariant under the action of a crystallographic group and the symmetries of their projections into a function defined on a plane. In particular, we introduce a formalism to explain how the study of bifurcation theory, in the context of symmetries, is applied to the theory of projection we present.
- Track 3: Chemical Crystallography
Location: Houston
Session Introduction
Boniface P. T. Fokwa
University of California-Riverside, USA
Title: Magnetic ordering, frustration and possible spin liquid state from 1D Cr3-triangles in the TiCrIr2 xOsxB2 series
Biography:
Boniface Fokwa completed his PhD in 2003 from the Dresden University of Technology (Germany) and postdoctoral studies from the RWTH Aachen University (Germany). He is an Associate Editor for Encyclopedia of Inorganic and Bioinorganic Chemistry (Wiley). He has published more than 70 papers in reputed journals and has won several awards including the prestigious Heisenberg Fellowship from the German Research Foundation and was visiting scientist at University of Auckland (New Zealand) and Cornell University as well as visiting Professor at UCLA.
Abstract:
A new series of compounds TiCrIr2 xOsxB2 (x = 0 - 2) was successfully synthesized and characterized using X-ray diffraction as well as energy-dispersive X-ray analysis. All members of the series crystallize in the hexagonal non-centrosymmetric Ti1+xOs2ï€xRuB2 structure type (space group P6 Ì…2m, no. 189, Pearson symbol hP18). The structure contains trigonal planar B4 units strongly interacting with triangles of magnetically active Cr atoms, which are stacked on each other to form isolated Cr3-chains along the c-axis. Magnetization measurements of TiCrIr2B2 (34 valence electrons, VE) reveal ferrimagnetic behavior below TC = 275 K with a large, negative Weiss constant of ï€750 K. Density functional theory calculations demonstrate magnetic frustration due to indirect antiferromagnetic interactions within the Cr3 triangles competing with direct ferromagnetic interactions. Tuning the valence electron count by replacing Ir with Os changes the magnetic behavior in the series. Magnetization measurements of TiCrIrOsB2 (33 VE) and TiCrOs2B2 (32 VE) exhibit paramagnetic behavior with features reminiscent of the spin liquid state. Interestingly, the crystal orbital Hamilton population (COHP) of TiCrIr2B2 indicates Cr−Cr antibonding interactions above 32.9 VE, but part of the Cr−Cr antibonding region is already occupied in TiCrOs2B2 even though it has 32 valence electrons. Therefore, the TiCrIr2 xOsxB2 (x = 0 - 2) series do not quite follow rigid band approximation.
Biography:
Yuichi Shimazaki was born in 1970 in Toyama prefecture, Japan. He received his Doctor’s degree in science from Nagoya University in 2000 under the supervision of Professor Osamu Yamauchi. He joined Professor Yoshinori Naruta’s group at Kyushu University as Assistant Professor and worked on the redox behavior of various metal porphyrin complexes as models of the active site of metalloenzymes. In 2008 he was promoted to Associate Professor at the College of Science, Ibaraki University. His research interests include the oxidation chemistry of the complexes of various metal ions, model studies of metalloenzymes, bioorganometallic chemistry, and weak interactions in metal-organic molecule systems.
Abstract:
Oxidation chemistry of redox active transition metal complexes with pro-radical ligands and their detailed electronic structures have been actively pursued in recent years. An “experimental†valence state of metal complexes is sometime different from the “formal†oxidation state, especially in the species having redox active ligands. This difference can be seen in biological system, such as iron(IV)-porphyrin ï°-cation radical in some heme proteins and copper(II)-phenoxyl radical in galactose oxidase (GO). Many efforts for determination of the experimental oxidation number have been close to the goal of the “truth oxidation state†in various oxidized metal complexes with redox-active ligands. Depending on the relative energies of the redox-active orbitals, metal complexes with non-innocent ligands exist in two limiting descriptions, either a metal-ligand radical (Mn+(L•)) or a high valent metal (M(n+1)+(Lï€)) complex. The reaction mechanisms of artificial and biological catalysts depend on the electronic structures of the high valent intermediates. However, structural characterizations of these species by X-ray diffraction methods have been rare due to their stability. Recently, some artificial metal−phenoxyl radical complexes as models of GO have been synthesized and successfully characterized by X-ray crystal structure. The one-electron oxidized metal-phenolate complexes showed various electronic structures depending on small perturbations, such as substitution of the phenolate ring and the chelate effect of the phenolate ligands and so on. In this presentation, I will focus on X-ray crystal structures of the one-electron oxidized metal–phenolate complexes in the case of metal complexes of diphenolate Schiff base ligands with 2N2O donor sets. Especially electronic and crystal structure relationship such as differences of metal-phenoxyl radical and high-valent metal phenolate complexes will be discussed.
Takeru Ito
Tokai University, Japan
Title: Oxide cluster-surfactant hybrid single crystals toward solid electrolyte
Biography:
Takeru Ito received his Doctor’s degree in 2001 at the University of Tokyo. After postdoctoral studies for three years (the University of Tokyo and Tokyo Institute of Technology), he was appointed as an assistant professor at Tokyo Institute of Technology. He moved to Tokai University in 2008, and now is an associate professor. His research interests are focused on the synthesis and functionalization of polyoxometalate-surfactant hybrid crystals.
Abstract:
To synthesize highly conductive materials is crucial for lithium-ion or fuel-cell battery technology due to their structural stability and easiness for handling. A promising strategy is to hybridize inorganic and organic molecular components and to construct crystalline layered structures beneficial to the emergence of conductive property. Polyoxometalate oxide cluster anions having characteristic redox properties are suitable as inorganic components. Polyoxometalates can be hybridized with cationic surfactants to form stable layered single crystals. Such ionic crystals are rare, and both polyoxometalate and surfactant components can be variously selected to build up functional inorganic-organic hybrid crystals. The polyoxometalate-surfactant hybrid crystals were synthesized by cation-exchange reaction with pH-adjusted solutions of molybdate, tungstate, and vanadate oxoanions. Single crystals were obtained from the filtrate solutions or by recrystallization of the crude precipitates, and subjected to X-ray structure analyses. Decatungstate and tetramolybdate anions formed stable single crystals together with hexadecylpyridinium. The crystals exhibited the alternate stacking of polyoxometalate inorganic layers and surfactant organic layers. The obtained conductivity values were in the range of 10−6 to 10−5 S cm−1 order over 423 K under anhydrous atmosphere. Decavanadate anion formed layered crystals with alkyltrimethylammonium. The hybrid crystals which comprise diprotonated decavanadate species exhibited anhydrous proton conductivity at intermediate temperatures (> 373 K), which is possible for proton-conducting electrolyte of fuel cells.
Jean-Guillaume Eon
Universidade Federal do Rio de Janeiro, Brazil
Title: Topological features in crystal structures: A quotient graph-assisted analysis of underlying nets and their embeddings
Biography:
Jean-Guillaume Eon completed his PhD from Université de Technologie de Compiègne (France) in 1984. He is the director of a research group on Oxidation Catalysis at the Federal University of Rio de Janeiro, Brazil. He has published more than 60 papers in chemistry and crystallography journals and has been serving as an editorial board member for Acta Crystallographica, Section A.
Abstract:
Topological properties of crystal structures may be analyzed at several levels, depending on the representation and the topology that have been assigned to the crystal. We consider here the combinatorial or bond-topology derived from the underlying net, which is independent of its embedding in space. Periodic nets representing one-dimensional complexes, or the associated graphs, characterize the skeleton of chemical bonds within the crystal. By topological features we mean the different possible building units that can be used to describe a crystal structure and the mode of connection between these units, independently of the geometrical details of the structure. Such building units can be finite or infinite, corresponding to one-, two- or even three-periodic subnets. Examples of infinite units include linear chains or sheets of corner- or edge-sharing polyhedra. Periodic nets can be represented by their labelled quotient graphs. This presentation will deal with the trace or projection of building units on labelled quotient graphs. Decomposing periodic nets into their building units relies on graph-theoretical methods classiï¬ed as surgery techniques. The most relevant operations are edge subdivision, vertex identiï¬cation, edge contraction and decoration. Instead, these operations can be performed on labelled quotient graphs, evidencing in almost a mechanical way the nature and connection mode of building units in the derived net. Various examples will be discussed with the visual support provided by the program package TOPOS, ranging from ï¬nite building blocks to three-periodic subnets. Among others, the structures of strontium oxychloride, spinel, lithiophylite and garnet will be addressed.
Alejandro Dorazco-González
National Autonomous University of Mexico, Mexico
Title: A coordination polymer with lewis acid sites for capture of aromatic N-donors ligands and cyanide based on Zn(II) 1,4-benzenedicarboxylate
Biography:
Alejandro Dorazco was born in Mexico. He joined at Center of Sustentable Chemistry CCQIS at National University Autonomous of Mexico (UNAM) in 2013 as full-time Associate Researcher. He obtained his Ph. D. in 2010 with a thesis in the field of Supramolecular Chemistry in the group Prof. Anatoly Yatsimirsky at UNAM, subsequently, he joined the group of Prof. Kay Severin, Swiss Federal Institute of Technology in Lausanne, as a postdoctoral fellow. In 2013, he started independent research projects focused on luminescent chemosensors, Supramolecular Chemistry and Crystal Engineering
Abstract:
The development of selective crystalline materials for capture of aromatic organic N-donors ligands and cyanide anion is a current topic in material sciences, environmental monitoring, quality control of water sources and supramolecular chemistry. Capture and store of low-weight chemical species (mainly gases) by mesoporous coordination polymers (CPs) based on metal-benzene multi carboxylate compounds has been studied thoroughly in the past few decades, this approach need CPs with large pores and frequently is not feasible preparing them into medium and large-scale by their chemical instability to hydrolysis or releasing molecules solvents which results in loss of the tridimensional structure and capture properties. In principle a stable molecular container for amines or cyanide can be achieve with CPs containing Lewis acid sites such as Zn(II) or Cd(II) with available coordination sites initially occuped by solvent molecules as DMF which provide structural and chemical stability and they may be replaced by ligands with higher affinity for the metal center as quinoline, pyridine and cyanide, without need to large pores. In this way, an 1D dinuclear coordination polymer [Zn2(1,4-BDC)2(DMF)2] (1) (1,4-benzenedicarboxylate) was synthesized and studied as molecular receptor for pyridine, quinoline, isoquinoline and cyanide from solutions of N-donors containing crystals of (1). Solid state transformations of crystals of (1) by partial exchange of solvent molecules with quinoline and isoquinolin was observed after of 24 h. at room temperature, on the other hand, cyanide and pyridine completely displace DMF molecules of (1) after 24 h. Releasing of DMF molecules was observed by 1H NMR measurements and the precence of isoquinoline, pyridine and cyanide in treated solid samples of (1) was detected and quantified by solid state 13C CP/MAS NMR, TGA, DSC and IR experiments. X-ray single crystal structures of [Zn2(1,4-BDC)2(isoquinoline)2] (2) and [Zn(1,4-BDC)(Py)2] (3) supports the captura of N-donors involving the coordination bond of nitrogen atom to metal center. From spectroscopic studies the affinity order of [Zn2(1,4-BDC)2(DMF)2] (1) to guest molecules was defined as CN- > Py > isoquinoline >> quinoline. Solid state transformations, structural and spectroscopic studies will be discussed in the presentation.
Biography:
Kalainathan Sivaperuman earned his doctorate in Physics from Anna University, Chennai, in 1992. At present, he is the Senior Professor and Deputy Director, Centre for Crystal Growth, VIT University, Vellore. So far he has produced 16 Ph.D’s and 10 M.Phil’s. At present, 6 scholars are working towards their Ph.Ds under his guidance. He has a total of 24 years of research experience in the field of Crystal Growth and he is the principal investigator of ongoing funded projects. He has published more than 160 papers in reputed journals. He has awarded Prof.P.Ramasamy National Award for Crystal Growth in 2009 by IACG.
Abstract:
The search and design of highly efficient organic nonlinear optical (NLO) single crystals are extremely important for the present day technological requirements. We present two D-π-A organic core structures leading to highly efficient nonlinear optical (NLO) single crystals, 2-[2-(2,4-Dimethoxy-phenyl)-vinyl]-1-ethyl-pyridinium iodide (DBSI) and 1-Ethyl -2-[2-(4-hydroxy-phenyl)-vinyl]- pyridinium iodide (HSPI). Single crystals of the above two materials were successfully obtained from the methanol-acetonitrile mixed solvent by slow evaporation method. Single crystal X-ray diffraction analysis revealed that both the crystals crystallized in centrosymmetric crystal system with a triclinic space group Pī and monoclinic space group C2/c. Theoretical calculations were performed to derive HOMO-LUMO energies and dipole moment by using Sparton’14 V1.0.1 program. The actual composition and the expected functional groups have been identified by 1H NMR and FTIR analysis. The optical transmittance window and band gap were ascertained by UV- Visible -NIR studies. Thermal studies exhibited that the grown crystals were thermally stable up to 232.5oC and 226.6oC. The surface features of the grown crystal were assessed by using an optical microscope. The dielectric studies were performed. Laser-induced surface damage and mechanical stability of grown crystal were studied to explore its suitability towards device fabrications. The third-order nonlinear optical susceptibility was derived from Z-scan technique, and it was found to be 1.020 x 10-3 esu (DBSI) and 4.40 x10-4 esu (HSPI) respectively, which is appreciably higher than some reported stilbazolium derivatives. All these obtained results in the present work making it an attractive candidate for NLO applications such as electro-optics and THz-wave generation.
Marietjie Schutte-Smith
University of the Free State, South Africa
Title: The Investigation of chemical crystallography and kinetic reactivity of Re(I) tricarbonyl complexes
Biography:
Marietjie Schutte-Smith has completed her PhD at 28 years of age at the University of the Free State, Bloemfontein, South Africa. She was appointed as a lecturer immediately after the completion of her PhD from 2012 and were promoted to senior lecturer in 2016. At the age of 33 she is supervising two MSc and six PhD students and she has published 21 articles.
Abstract:
The coordination chemistry of rhenium and technetium has gained major interest for the possible use in radiopharmacy, due to several favorable properties. A number of fac-[M(CO)3]+ (M = Re, 99mTc) type complexes have been synthesized to date with a large number of ligand systems. The three labile aqua ligands on the starting synthon fac-[Re(CO)3(H2O)3]+ can easily be substituted by a variety and/or combinations of ligands producing stable compounds and potential radiopharmaceuticals with many different characteristics. We focus on the fac-[Re(CO)3]+ moiety and related compounds by adopting the [2+1] approach. The solid state behaviour and the effects like the charge, the donor atoms and electron donating and withdrawing effects of the ligands coordinated to the metal are explored. The influence of the coordinated bidentate ligands on the rate of substitution by a variety of entering ligands in solution is also investigated. The aqueous kinetics of fac-Re(I) tricarbonyl complexes are virtually unexplored. We synthesized a water soluble complex which allowed us to evaluate the reactivity of a fac-Re(I) tricarbonyl type complexes in aqueous medium which is imperative for biomedical application. The first high pressure substitution kinetics on a fac-[Re(L,L’-bid)(CO)3(CH3OH)] complex are also reported here.
- Track 6: Recent development in the X-ray studies
Location: Houston
Session Introduction
Borislav Angelov
Czech Academy of Sciences, Czech Republic
Title: Recent advances and perspectives in fast time-resolved X-ray crystallography of proteins
Biography:
Dr. Borislav Angelov has completed his PhD study at the Bulgarian Academy of Sciences (Sofia, Bulgaria). He performed postdoctoral research work at the Helmholtz Centrum Geesthacht (Hamburg area, Germany) and the University of Aarhus (Denmark) before his appointment at the Czech Academy of Sciences. Dr. Angelov is a Senior scientist at the ELI beamlines, Institute of Physics of the Czech Academy of Sciences. He has published more than 50 papers in international journals and has experience in structure analysis from more than 15 large scale user facilities worldwide.
Abstract:
The purpose of this work is to outline the new developments and perspectives for time resolved X-ray scattering and diffraction analysis on a time scale from femtoseconds to milliseconds. The utilization of femtosecond laser pulses for the generation of X-rays has opened new opportunities for structural studies of fast kinetic processes. This new technology is essentially different from the operation principles employed at the synchrotron sources and the free electron lasers. The ELI beamlines facility is planned to start operation by the end of 2016 near Prague in Czech Republic. It will provide unique advantages for time-resolved crystallography based on laser-driven plasma X-Ray Source (PXS). The generated pulses will span approx. 100 fs with a repetition rate of 1 kHz. The scattered and diffracted X-rays by the sample will be counted using a Dectris Eiger 1M area detector, which operates at the same frame rate as the source, i.e. 1 kHz. The created setup can be combined with several pump probe lasers in order to study the fast kinetics of dynamic biological systems, for example the protein photo systems. Under the conditions of low flux, the generation of a crystallographic image requires several pulses to be obtained. Therefore, serial femtosecond crystallography at tabletop XPS sources is becoming feasible.
D. K. Saldin
University of Wisconsin-Milwaukee, USA
Title: Structure determination by correlated scattering
Biography:
Dilano Saldin has completed his D. Phil. From the University of Oxford in the UK, After some postdoctoral work at Oxford, he took up a position of Reserch Fellow at Imperial College.London from 1981-1988. In 1988 he joined the Physics Departtment of the University of Wisconsin-Milwaukee, where he now holds the title of Distinguished Professor.
Abstract:
In general what is measured on x-ray scattering are the intensities of x-rays. What is more if the scattering units are all identical and identically oriented, a measurable intensity is found from the unit cell even with relatively weak x-rays. Ingenious methods have been devised in x-ray crystallography for deducing the phases of the scattered x-rays and consequently the amplitudes of scattering. A Fourier transform of the scattered amplitudes gives the electron density of the unit cell and this often allows the structure to be deduced. The advent of the new x-ray sources such as those from an x-ray free electron laser (XFEL) allows a paradigm shift for the measurement of molecular structure. The increase in intensity of ten billion-fold allows the possibity of structure determination even if proteins do not form crystals by scattering off individual molecules. A translation of the molecule gives rise to exactly the same intensities, but as rotation in general changes the intensities totally. However even in the case of rotation a quantity called the angular correlations, while dependent on the structure, do not depend of the state of rotation or translation and is thus ideally placed to allow structure determination of molecules typically injected into an XFEL in the form of particles of constant structure but unknown orientation or position. What is more, the absence of translational periodicity as in a crystal, allows the determination of the phases of the scattered amplitudes by an iterative phasing algorithm. We will discuss the use of angular correlations to determine the structures of proteins and viruses, with an XFEL and even raid time resolved changes in their structure
Kakoli Bose
Tata Memorial Centre, India
Title: Structural insights into mode of regulation of serine protease HtrA2
Biography:
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Abstract:
High-temperature requirement protease A2 (HtrA2), a proapoptotic serine protease is involved in maintaining mitochondrial homeostasis. This multifaceted protein has been implicated in several diseases including cancer and neurodegeneration thus making it an important therapeutic target. HtrA2 comprises a short N-terminal region, a serine protease domain and regulatory PDZ (protein-protein interaction) domain. The complex trimeric structure, intricate PDZ-protease crosstalk, allosteric mechanism of activation that is mediated both through its N- as well as C-termini, and most importantly its involvement in both caspase-dependent as well as independent apoptotic mechanism has made this protease an important molecule for biomedical research. Unlike other members of the family, human HtrA2 has been found to be activated through its short N-terminal region in addition to the classical substrate/adapter binding pocket in the PDZ domain. Interaction with inhibitor of apoptosis proteins (such as XIAP) through its N-terminus, leads not only to subsequent cleavage of the molecule but also simultaneous activation of HtrA2, suggesting a ‘positive feedback’ mechanism. Similar mechanism is observed for PDZ-mediated substrate binding and activation as well. Therefore, understanding this complex mechanism and identifying the dual regulatory switch of its allosteric activation will help devise modulators with desired characteristics for therapeutic intervention against diseases it is associated with. It will also shed light on how point mutations lead to its inactivation as observed in diseases such as Alzheimer’s and Parkinson’s. Keeping these in mind, here we aim at understanding the structural correlates of mode of activation of HtrA2 and several pathogenic mutants (in complex with substrates) at atomic level using X-ray crystallography and biophysical probes.
- Track 5: Crystallography in Materials Science
Location: Houston
Chair
Andriy Lotnyk
Leibniz Institute of Surface Modification, Germany
Session Introduction
Andriy Lotnyk
Leibniz Institute of Surface Modification, Germany
Title: Local atomic arrangement in Ge-Sb-Te phase-change thin films
Time : 10:50-11:15
Biography:
Andriy Lotnyk has completed his PhD in 2007 from the University of Halle working at the Max Planck Institute of Macrostructure Physics (Halle) and Post-doctoral studies from the same Institute. He has been a permanent staff member at the Faculty of Engineering, CAU of Kiel in 2009-2011. Presently, he is a group leader of the group “Structure Determination and Electron Microscopy” at the Leibniz Institute of Surface Modification (IOM). He was awarded by the Otto Hahn Medal from the Max Planck Society in 2008. He has authored and co-authored more than 50 scientific publications in peer reviewed journals and about the same number of conference papers.
Abstract:
Phase change materials (PCM), such as Te-based Ge2Sb2Te5 (GST), are known from optical memory applications and can be also used in non-volatile next generation random access memory. The relevant phases of GST are an amorphous phase, a metastable cubic rock salt like structure and a stable hexagonal layered structure. However, the atomic arrangements in the GST lattices are not well-understood and still under discussion. Insights into the local atomic arrangement of layered Ge-Sb-Te compounds are of particular importance from a fundamental point of view as well as for optical and electronic applications such as data storage, thermoelectric and ferroelectric. In this work, the local atomic arrangement in metastable GST and in Ge-Sb-Te thin films consisting of GST, Ge1Sb2Te4 and Ge3Sb2Te6 layered crystal structures are studied by using a combination of atomic-resolution aberration-corrected (Cs-corrected) high-angle annular dark-filed scanning transmission electron microscopy (HAADF-STEM) and detailed theoretical image simulation approaches. By comprehensive analyses of experimental and simulated HAADF-STEM image intensities, a structural model for metastable Ge2Sb2Te5 is proposed. In addition, the proper stacking sequences in the Ge-Sb-Te phases are determined. The obtained data are discussed with respect to existing experimental and theoretical structure models reported for bulk Ge-Sb-Te materials.
Christian Bonhomme
Pierre et Marie Curie University, France
Title: NMR crystallography: When nuclear magnetic resonance and diffraction meet
Time : 11:15-11:40
Biography:
Christian Bonhomme has completed his PhD from Pierre et Marie Curie University (UPMC) in Paris, France. Currently, he is full Professor at UPMC. He has been Invited Professor at the Department of Physics, Warwick University, UK. He is the leader of the SMiLES group at the Laboratoire de Chimie de la Matière Condensée de Paris. He has published more than 105 papers in reputed journals and has given 50 invited conferences in the fields of NMR, NMR Crystallography and Materials Science.
Abstract:
This presentation will expose an overview and the latest methodological developments in NMR Crystallography. Such a concept appeared recently in the solid state NMR community following the pioneering work of Pickard and Mauri and their implementation of the GIPAW method. Such a method allows the calculations of NMR parameters from first principles (at the DFT level) under periodic boundary conditions. Such calculations lead to full NMR tensorial parameters for all interactions (chemical shift, quadrupolar, J coupling, Knight shift) and for all nuclei described in the asymmetric unit of the crystal. GIAPW has been also extended to amorphous and disordered derivatives. The complementarity of diffraction techniques (X-rays and neutrons) and solid state NMR will be presented in the frame of NMR Crystallography. The goal of this approach is to propose new perspectives for the refinement of structures. The following questions will be raised: are NMR parameters sufficient for a full description of a crystal structure? Are a limited number of chemical environment representative of glassy architecture? A large panel of examples will illustrate the NMR Crystallography concept: inorganic structures, organic/inorganic hybrids, disordered materials such as biocompatible glasses doped with various cations. Applications of GIPAW will be presented as well in the frame of EPR and other spectroscopies.
Tamotsu Inabe
Hokkaido University, Japan
Title: Directionally tunable and mechanically deformable ferroelectric crystals from rotating polar globular ionic molecules
Time : 11:40-12:05
Biography:
Tamotsu Inabe has completed his PhD in 1981 from Hokkaido University, Japan, and Post-doctoral studies from Northwestern University (1981–1984). He is a full Professor from 1993 at the Division of Chemistry, Faculty of Science, Hokkaido University. He has published more than 250 papers mainly in the field of Solid-State Chemistry. He was honored A. K. Doolitle Award from A.C.S. and The Chemical Society of Japan Award for Creative Work. His research interest includes “Solid-state chemistry of molecular materials, crystal design, and electronic functional materials”.
Abstract:
Ferroelectrics are used in a wide range of applications, including memory elements, capacitors and sensors. Recently, molecular ferroelectric crystals have attracted interest as viable alternatives to conventional ceramic ferroelectrics because of their solution processability and lack of toxicity. Here, we show that a class of molecular compounds known as plastic crystals can exhibit ferroelectricity if the constituents are judiciously chosen from polar ionic molecules. The intrinsic features of plastic crystals, for example, the rotational motion of molecules and phase transitions with lattice-symmetry changes, provide the crystals with unique ferroelectric properties relative to those of conventional molecular crystals. This allows a flexible alteration of the polarization axis direction in a grown crystal by applying an electric field. Owing to the tunable nature of the crystal orientation, together with mechanical deformability, this type of molecular crystal represents an attractive functional material that could find use in a diverse range of applications.
Kosuke Suzuki
Gunma University, Japan
Title: Redox orbital and electronic structure in energy materials by Compton scattering spectroscopy
Time : 12:05-12:30
Biography:
Kosuke Suzuki has completed his PhD at Gunma University. His interest includes “Electronic structure of energy materials and Compton scattering technique”. He has published 29 papers in journals, proceedings and reports.
Abstract:
Compton scattering is one of the powerful tool for investigating electronic structure of the materials. Advantage of this technique is that Compton scattering use high-energy X-rays over 100 keV, which enables bulk sensitive measurement. Furthermore, Compton profile obtained from this technique reflects occupied orbitals of electrons upon Li insertion. We have applied this technique to electrode materials used for Li-ion battery, especially LixMn2O4 and LixCoO2. The Compton scattering experiments were performed on the BL08W beamline at the SPring-8 synchrotron facility in Japan. Results of our Compton profile measurement show an increment of itinerant electrons with Li insertion in both materials. By comparing experiment with first-principles calculations, we deduce that this increase of itinerant electrons has O 2p character. On the other hand, 3d orbitals of transition metals become less localized at the range of Li concentration corresponding to the optimal battery performance both for the LixMn2O4 and LixCoO2 cathodes. This 3d orbitals delocalization effect is associated with electron conductivity properties. Therefore, Compton scattering spectroscopy can provide new descriptors for electrode conductivity.
Srikanth Patala
North Carolina State University, USA
Title: Algorithms for generating coincidence site lattices (CSLs) and near-CSLs in arbitrary Bravais lattice systems
Time : 12:30-12:55
Biography:
Srikanth Patala received his BTech in Metallurgical and Materials Engineering from the Indian Institute of Technology Madras in 2005 and did his PhD in Materials Science and Engineering from the Massachusetts Institute of Technology in 2011. Prior to joining the NC State Faculty in 2013, he was a Post-doctoral Researcher in the Department of Materials Science and Engineering at Northwestern University. His research is focused on developing computational and analytical techniques to quantify the structure-property relationships in complex heterogeneous materials.
Abstract:
The formulation of coincidence site lattices (CSLs) has played a fundamental role in the analysis of interfaces in both experiments and simulations of inorganic materials systems. For example, the prediction of habit planes during precipitation and phase transformations relies on the determination of near-CSLs between the parent and the product lattice. The distributions of internal interfaces are generally analyzed as a function of their corresponding Σ-misorientations. Therefore, the ability, to automatically generate the Σ-rotations and their corresponding CSLs will not only enable the high-throughput prediction of interface structure-property relationships but will also help understand microstructure evolution during phase transformations. Grimmer, in a series of articles, has proposed the generating functions for determining the coincidence site lattices for cubic, hexagonal, trigonal and tetragonal Bravais lattices. These generated routines increased in complexity as the underlying symmetry of the lattice is reduced. In this talk, I will present a simple algorithm that computes all the unique CSL generating rotations for any Σ, and in arbitrary Bravais lattice systems. The algorithm involves two simple steps: (i) determination of all the unique sub-lattices of volume Σ; and (ii) the computation all the unique pairs of sub-lattices that are not related by the symmetry operations of the underlying crystals. I will also present strategies for extending this algorithm for computing near-CSL rotations between any two Bravais lattice systems (i.e. both homo-phase and hetero-phase interfaces).
Melanie John
Ludwig-Maximilians-Universität München, Germany
Title: Synthesis of (doped) ABO2 nanoparticles: Can this work at temperatures ≤90°C without using an additional reducing agent?
Time : 12:55-13:20
Biography:
Melanie John completed her BSc in Earth Sciences in 2012. She continued her studies in Geomaterials and completed her MSc in 2014. Within two years, she completed her PhD studies. She developed an environmental sustainable concept to extract heavy metals from aqueous solutions. At the same time, she created a new method to synthesize nanoparticles as delafossite and special core-shell composite materials at low temperatures <90°C. Now, she is continuing to widen her interdisciplinary research field. She published papers in reputed journals.
Abstract:
Delafossite (ABO2) is in focus of extensive research for its special magnetic, photo- and electrochemical as well as antiviral properties. Delafossite structures shows a wide variability of chemistry (A=e.g. Cu, Ag and B=e.g. Fe, Mn, Cr, Co, Al) and are used for diverse technical applications including catalysis, p-type conduction oxide, solar cells, or as luminescent material. Many physical properties are directly related to grain size, but most of the common synthesis routes as solid-state reactions, sol-gel or hydrothermal techniques lead to crystals in micron size. With the Lt-delafossite process, a new synthesis route by precipitation and subsequent ageing, it is possible to gain pure nano-sized delafossite at temperatures ≤90°C. The synthesized product exclusively consists of hexagonal, platy crystals with a diameter of less than 500 nm. The thickness increases with increasing ageing time from 5 to 200 nm. In case of CuFeO2, green rust (GR), precipitates first. Additional supply of OH- leads to the transformation of GR to delafossite. At the same time, GR acts as reducing agent for Cu2+. The ratio of 3R and 2H polytype is directly controllable by NaOH supply. The magnetic properties of CuFeO2 prepared by Lt-delafossite process deviate from both, natural delafossite and samples synthesized by other routes. A new approach is to produce doped delafossite. However, the incorporation of foreign ions is limited. Partly, they are adsorbed on the surface and so hinder crystal growth especially in [001]. Moreover it promotes twinning of the crystals.
Rajni Kant
University of Jammu, India
Title: Crystallographic and molecular packing interaction analysis of cholest-based steroids: A CSD study
Time : 14:20-14:45
Biography:
Rajni Kant completed his PhD from University of Jammu (India) in 1989 and Post-PhD from Oxford University (UK) during 1994-95. Presently, he is Professor of Physics at University of Jammu and also the Editor-in-Chief for Open Journal of Inorganic Chemistry (Scirp, USA). He has guided 21 PhD students, 48 MPhil students and has published over 350 research papers in journals of international repute. He has authored a book titled “Applied Solid State Physics”, published by Wiley-India Ltd.
Abstract:
Biological activity of steroids is one of the most important reasons for their synthesis and structural characterization. Cholestane (C27H48), the parent compound of all steroids, is obtained by the removal of hydroxyl group (from C3 position) and reduction of double bond (between C5 and C6 atoms) from the basic cholesterol nucleus. A total number of twenty-three structures of cholestane derivatives were obtained from the CSD for a comparative analysis of their crystallographic structures, computation of their possible biological activities and molecular packing interaction analysis. Intermolecular interactions of the type X-H…A [X=C,O, N; A=O, Cl, N, Br, F] have been analysed for a better understanding of molecular packing in cholestane class of steroids and discussed on the basis of distance-angle scatter plots. A careful examination of the entire interaction data reveals that the C-H…O hydrogen bonding is quite predominant in cholestane derivatives. The nature of the substituent at C3 position of the cholestane nucleus makes these molecules very interesting candidates for hydrogen bonding analysis. In most of the cases, the substituent at C3 position is primarily responsible for the occurrence of intermolecular hydrogen bonding in cholestanes. These substitutions are linked by intermolecular hydrogen bonding which in turn help to understand the dynamics of stacking interactions in supramolecular structures. Similar studies have also been carried out on various other classes of Cholest-based steroids, viz. Cholane, Pregnane, etc., to look for a possible solution to some of the following queries: (i) Could structural diversity in steroids be explored for a generalized crystallographic co-relations? (ii) Which of the X-H...A interactions (intra- or intermolecular) are dominant in various classes of steroids? (iii) Is there any preference of linearity for different hydrogen bonded interactions? Results of the emperical analysis of various kinds of cholest-based steroids as picked up from the CSD shall be presented.
Li-Xian Sun
Guilin University of Electronic Technology, China
Title: Synthesis and applications of porous materials for gas storage
Time : 14:45-15:10
Biography:
Li-Xian Sun has completed his PhD in 1994 from Hunan University and Post-doctoral studies from Jena University supported by Alexander Von Humboldt Fellowship and from National Institute of Advanced Industrial Science and Technology by NEDO fellowship. He is the Dean of School of Material Science and Engineering, Guilin University of Electronic Technology, Fellow of RSC (FRSC), Counsellor of International Association of Chemical Thermodynamics (IACT), Vice Chairman of of committee on Chemical Thermodynamics and Thermal Analysis of Chinese Chemical Society. He has published more than 300 papers in reputed journals and has been serving as a regional Editorial Board Member of Thermal Analysis & Calorimetry.
Abstract:
Studies of economic, highly efficient and safe gas storage materials (GSMs) are of great importance in the fuel cells based vehicles and CO2 capture. In our lab, we focus on studies on GSMs for H2 and CO2 based one micro/nano-technology. A series of metal organic frameworks (MOFs) and porous carbon materials such as grapheme for GSMs were synthesized. Their crystal structures, gas storage and thermodynamic properties were systematically evaluated. Furthermore, relationship of structure-activity were explored.
Myobin Jeon
Korea Advanced Institute Science and Technology, Republic of Korea
Title: Surfactant-mediated shape evolution of 3D organic molecular architecture
Time : 15:10-15:35
Biography:
Myobin Jeon has completed her Bachelor of Science in Chemistry from Pusan National University (PNU) in 2014. She is a student in the Intergrated Master’s & PhD Program at the Department of Chemitry from graduate schools at KAIST.
Abstract:
Systematic studies of the mechanism of the surfactant-controlled self-assembly of organic molecules are challenging in the field of crystal engineering and nanotechnology. Here, we discuss the shape evolution of three-dimensional molecular architectures (foldectures) formed from the self-assembly of a b-peptide foldamer. The evolution of the shape from a square plate to a square pyramid was observed, and the molecular packing structure was analyzed by diffraction experiments. This shape evolution arises from the passivation of the surfactants on the crystal facets and synergistic effect of their counterions. Moreover, we performed surface-energy calculations through a molecular dynamics simulation to demonstrate the roles of additives in the crystal growth mechanism. These findings would bolster our understanding of the interactions between surfactants and the interfaces of organic molecules and thus provide deeper insight into the design of functional organic materials.
Takahiro Sakagami
Ehime University, Japan
Title: A new approach for estimating the density of non-crystalline materials
Time : 15:55-16:20
Biography:
Takahiro Sakagami has received his Master of Science degree in Physics in 2010 from Ehime University. He has been working at AGC Techno Glass Co., Ltd since 2010. He has done his PhD course in the Department of Physics from Ehime University.
Abstract:
We propose a novel approach with which to estimate the density of liquids. The approach is based on the assumption that the systems would be structurally similar when viewed at around the length scale (inverse wavenumber) of the first peak of the structure factor, unless their thermodynamic states differ significantly. The assumption was implemented via a similarity transformation to the radial distribution function to extract the density from the structure factor of a reference state with a known density. The method was first tested using two model liquids (one is a simple liquid composed of the modified Lennard-Jones particles and the other is a molecular liquid composed of rigid tetrahedrons interacting via van der Waals forces), and could predict the densities within an error of several percent unless the state in question differed significantly from the reference state. The method was then applied to related real liquids, and satisfactory results were obtained for predicted densities. The possibility of applying the method to amorphous materials is shown, taking GeO2 glass as an exmaple. By choosing GeO2 at 8.5 GPa as a reference state, the method could satisfactorily reproduce the densities at higher pressures. The present method may thus pave the way for estimating density of high-density amorphous materials to which pycnometry is hardly applicable.
Janhavi Talegaonkar
Smt. P. K. Kotecha Mahila Mahavidyala, India
Title: Effect of change in structural properties on gas sensing performance of polyaniline-SrO2 nanocomposite
Time : 16:20-16:45
Biography:
Janhavi Talegaonkar is a Research Scholar and has completed her Master’s in Philosophy (2009), from North Maharashtra University, Jalgaon, (M.S.), India. Presently, she is an Assistant Professor in the Department of Physics, at Smt. P. K. Kotecha Mahila Mahavidyala, Bhusawal, (M.S.) India. She is pursuing PhD under the guidance of Prof. D. R. Patil. Her two papers have been published in reputed international journals.
Abstract:
Polyaniline is semi-crystalline polymer but it`s structure is studied rarely. Extensive study of synthesis, characterization and application of polyaniline and polyaniline-SrO2 composites has been carried out. Polyaniline having phenolic group as aromatic substituent and it`s nanocomposite samples with SrO2 were successfully fabricated by photo-induced polymerization method with various concentrations of SrO2. Prepared samples were then characterized by XRD, FTIR, SEM, EDAX, UV-Visible absorption spectra and gas sensing performance was checked for various gases. Parameters such as melting point, solubility, stability, morphology, electrical properties and hence gas sensing properties shows great dependence on crystal arrangement of organic component. Hence, crystal structure determination of newly developed component is very important. Analysis of XRD peaks of pure polyaniline and polyaniline-SrO2 composite exhibits structural change and percentage of crystallinity. Polyaniline-SrO2 composite exhibit tetragonal structure. The parallel and ordered package of pure polyaniline was studied from XRD peaks. FTIR peaks of polyaniline-SrO2 nanocomposite samples were taken to evaluate the interaction between polyaniline and SrO2 particles. As compare to pure polyaniline, UV-visible spectra of polyaniline-SrO2 nanocomposite shows shift towards lower wavelength. It indicates incorporation of SrO2 particles polyaniline matrix. Hence, exhibits surface:volume ratio. It reveals in improved electrical conductivity. Thermal conductivity exhibits positive temperature coefficient of resistor of prepared thick film of pure polyaniline and polyaniline-SrO2 nanocomposite. Gas sensing property of prepared samples was studied with respect to operating temperature, selectivity of CO2 against other gases response and recovery profile and long term stability of samples. As compare to pure polyaniline, change in structural properties of polyaniline-SrO2 nanocomposite shows enhanced performance for CO2 sensing.
Qixin Guo
Saga University,Japan
Title: Crystal growth of gallium oxide based wide bandgap semiconductors
Time : 16:45-17:10
Biography:
Prof. Guo received B. E., M.E., and Dr. E degrees in electronic engineering from Toyohashi University of Technology in Japan in 1990, 1992, and 1996, respectively. He is currently a Professor of Department of Electrical and Electronic Engineering, Saga University in Japan as well as Director of Saga University Synchrotron Light Application Center. His research interests include epitaxial growth and characterization of semiconductor materials. Prof. Guo has published more than 260 papers in scientific journals including Nature Communications, Advanced Materials, Physical Review B, and Applied Physics Letters.
Abstract:
The success in obtaining high quality β-Ga2O3 bulk substrates has positioned this material as a strong candidate for next-generation devices such as ultraviolet light emitting diode and photodetector. These achievements should be followed by bandgap engineering because it allows great flexibility in designing and optimizing the devices. A wider bandgap range is of great merit as it allows the design of devices such as high sensitive wavelength-tunable photodetectors, cutoff wavelength-tunable optical filters in more broad range. Al is a candidate to enlarge the bandgap of Ga2O3 because Al2O3 has a larger bandgap (~8.8 eV) and the similar electron structures of Al and Ga makes the alloy (AlGa)2O3 possible. In this work, we report on the crystal growth and characterization of (AlGa)2O3 films.We fabricated (AlGa)2O3 films on (0001) sapphire substrates by pulsed laser deposition using a KrF excimer laser source with wavelength 248 nm. The measurement of bandgap energies by examining the onset of inelastic energy loss in core-level atomic spectra using X-ray photoelectron spectroscopy is proved to be valid for determining the bandgap of (AlGa)2O3 films as it is in good agreement with the bandgap values from transmittance spectra. The measured bandgap of (AlGa)2O3 films increases continuously with the Al content covering the whole Al content range from about 5 to 7 eV. Recent progress on these materials will be presented.
- Track 3: Chemical Crystallography
Location: Houston
Chair
Jean Guillaume Eon
Universidade Federal do Rio de Janeiro, Brazil
Session Introduction
Jean-Guillaume Eon
Universidade Federal do Rio de Janeiro, Brazil
Title: Topological features in crystal structures: A quotient graph-assisted analysis of underlying nets and their embeddings
Time : 10:00 - 10:25
Biography:
Jean-Guillaume Eon completed his PhD from Université de Technologie de Compiègne (France) in 1984. He is the Director of a research group on Oxidation Catalysis at the Federal University of Rio de Janeiro, Brazil. He has published more than 60 papers in chemistry and crystallography journals and has been serving as an Editorial Board Member for Acta Crystallographica, Section A.
Abstract:
Topological properties of crystal structures may be analyzed at several levels, depending on the representation and the topology that have been assigned to the crystal. We consider here the combinatorial or bond-topology derived from the underlying net, which is independent of its embedding in space. Periodic nets representing one-dimensional complexes, or the associated graphs, characterize the skeleton of chemical bonds within the crystal. By topological features we mean the different possible building units that can be used to describe a crystal structure and the mode of connection between these units, independently of the geometrical details of the structure. Such building units can be finite or infinite, corresponding to one-, two- or even three-periodic subnets. Examples of infinite units include linear chains or sheets of corner- or edge-sharing polyhedra. Periodic nets can be represented by their labelled quotient graphs. This presentation will deal with the trace or projection of building units on labelled quotient graphs. Decomposing periodic nets into their building units relies on graph-theoretical methods classiï¬ed as surgery techniques. The most relevant operations are edge subdivision, vertex identiï¬cation, edge contraction and decoration. Instead, these operations can be performed on labelled quotient graphs, evidencing in almost a mechanical way the nature and connection mode of building units in the derived net. Various examples will be discussed with the visual support provided by the program package TOPOS, ranging from ï¬nite building blocks to three-periodic subnets. Among others, the structures of strontium oxychloride, spinel, lithiophylite and garnet will be addressed.
Yuichi Shimazaki
Ibaraki University, Japan
Title: X-ray crystal structures of the one-electron oxidized metal–phenolate complexes; geometric and electronic structures relationship
Time : 10:25-10:50
Biography:
Yuichi Shimazaki received his Doctor’s degree in Science from Nagoya University in 2000 under the supervision of Professor Osamu Yamauchi. He joined Professor Yoshinori Naruta’s group at Kyushu University as Assistant Professor and worked on the redox behavior of various metal porphyrin complexes as models of the active site of metalloenzymes. In 2008, he was promoted to Associate Professor at the College of Science, Ibaraki University. His research interests include the oxidation chemistry of the complexes of various metal ions, model studies of metalloenzymes, bioorganometallic chemistry, and weak interactions in metal-organic molecule systems.
Abstract:
Oxidation chemistry of redox active transition metal complexes with pro-radical ligands and their detailed electronic structures have been actively pursued in recent years. An “experimental” valence state of metal complexes is sometime different from the “formal” oxidation state, especially in the species having redox active ligands. This difference can be seen in biological system, such as iron(IV)-porphyrin p-cation radical in some heme proteins and copper(II)-phenoxyl radical in galactose oxidase (GO). Many efforts for determination of the experimental oxidation number have been close to the goal of the “truth oxidation state” in various oxidized metal complexes with redox-active ligands. Depending on the relative energies of the redox-active orbitals, metal complexes with non-innocent ligands exist in two limiting descriptions, either a metal-ligand radical (Mn+(L·)) or a high valent metal (M(n+1)+(L-)) complex. The reaction mechanisms of artificial and biological catalysts depend on the electronic structures of the high valent intermediates. However, structural characterizations of these species by X-ray diffraction methods have been rare due to their stability. Recently, some artificial metal−phenoxyl radical complexes as models of GO have been synthesized and successfully characterized by X-ray crystal structure. The one-electron oxidized metal-phenolate complexes showed various electronic structures depending on small perturbations, such as substitution of the phenolate ring and the chelate effect of the phenolate ligands and so on. In this presentation, I will focus on X-ray crystal structures of the one-electron oxidized metal–phenolate complexes in the case of metal complexes of diphenolate Schiff base ligands with 2N2O donor sets. Especially electronic and crystal structure relationship such as differences of metal-phenoxyl radical and high-valent metal phenolate complexes will be discussed.
Boniface P T Fokwa
University of California-Riverside, USA
Title: Magnetic ordering, frustration and possible spin liquid state from 1D Cr3-triangles in the TiCrIr2 xOsxB2 series
Time : 11:10-11:35
Biography:
Boniface P T Fokwa completed his PhD in 2003 from the Dresden University of Technology (Germany) and Post-doctoral studies from the RWTH Aachen University (Germany). He is an Associate Editor for Encyclopedia of Inorganic and Bioinorganic Chemistry (Wiley). He has published more than 70 papers in reputed journals and has won several awards including the prestigious Heisenberg Fellowship from the German Research Foundation and was Visiting Scientist at University of Auckland (New Zealand) and Cornell University as well as Visiting Professor at UCLA.
Abstract:
A new series of compounds TiCrIr2‑xOsxB2 (x=0-2) was successfully synthesized and characterized using X-ray diffraction as well as energy-dispersive X-ray analysis. All members of the series crystallize in the hexagonal non-centrosymmetric Ti1+xOs2-xRuB2 structure type (space group P
2m, no. 189, Pearson symbol hP18). The structure contains trigonal planar B4 units strongly interacting with triangles of magnetically active Cr atoms, which are stacked on each other to form isolated Cr3-chains along the c-axis. Magnetization measurements of TiCrIr2B2 (34 valence electrons, VE) reveal ferrimagnetic behavior below TC=275 K with a large, negative Weiss constant of -750 K. Density functional theory calculations demonstrate magnetic frustration due to indirect antiferromagnetic interactions within the Cr3 triangles competing with direct ferromagnetic interactions. Tuning the valence electron count by replacing Ir with Os changes the magnetic behavior in the series. Magnetization measurements of TiCrIrOsB2 (33 VE) and TiCrOs2B2 (32 VE) exhibit paramagnetic behavior with features reminiscent of the spin liquid state. Interestingly, the crystal orbital Hamilton population (COHP) of TiCrIr2B2 indicates Cr-Cr antibonding interactions above 32.9 VE, but part of the Cr-Cr antibonding region is already occupied in TiCrOs2B2 even though it has 32 valence electrons. Therefore, the TiCrIr2‑xOsxB2 (x=0-2) series do not follow rigid band approximation.
Takeru Ito
Tokai University, Japan
Title: Oxide cluster-surfactant hybrid single crystals toward solid electrolyte
Time : 11:35-12:00
Biography:
Takeru Ito has received his Doctor’s degree in 2001 at the University of Tokyo. After his Post-doctoral studies from the University of Tokyo and Tokyo Institute of Technology, he was appointed as an Assistant Professor at the Tokyo Institute of Technology. He moved to Tokai University in 2008, and now he is an Associate Professor. His research interests are focused on the synthesis and functionalization of Polyoxometalate Surfactant Hybrid Crystals.
Abstract:
To synthesize highly conductive materials is crucial for lithium-ion or fuel-cell battery technology due to their structural stability and easiness for handling. A promising strategy is to hybridize inorganic and organic molecular components and to construct crystalline layered structures beneficial to the emergence of conductive property. Polyoxometalate oxide cluster anions having characteristic redox properties are suitable as inorganic components. Polyoxometalates can be hybridized with cationic surfactants to form stable layered single crystals. Such ionic crystals are rare, and both polyoxometalate and surfactant components can be variously selected to build up functional inorganic-organic hybrid crystals. The polyoxometalate-surfactant hybrid crystals were synthesized by cation-exchange reaction with pH-adjusted solutions of molybdate, tungstate, and vanadate oxoanions. Single crystals were obtained from the filtrate solutions or by recrystallization of the crude precipitates, and subjected to X-ray structure analyses. Decatungstate and tetra-molybdate anions formed stable single crystals together with hexadecylpyridinium. The crystals exhibited the alternate stacking of polyoxometalate inorganic layers and surfactant organic layers. The obtained conductivity values were in the range of 10−6 to 10−5 S cm−1 order over 423 K under anhydrous atmosphere. Decavanadate anion formed layered crystals with alkyltrimethylammonium. The hybrid crystals which comprise diprotonated decavanadate species exhibited anhydrous proton conductivity at intermediate temperatures (>373 K), which is possible for proton-conducting electrolyte of fuel cells.
Marietjie Schutte-Smith
University of the Free State, South Africa
Title: The investigation of chemical crystallography and kinetic reactivity of Re(I) tricarbonyl complexes
Time : 12:00-12:25
Biography:
Marietjie Schutte-Smith has completed her PhD at the University of the Free State, Bloemfontein, South Africa. She was appointed as a Lecturer immediately after the completion of her PhD from 2012 and were promoted to Senior Lecturer in 2016. She is supervising two MSc and six PhD students and she has published 21 articles.
Abstract:
The coordination chemistry of rhenium and technetium has gained major interest for the possible use in radiopharmacy, due to several favorable properties. A number of fac-[M(CO)3]+ (M=Re, 99mTc) type complexes have been synthesized to date with a large number of ligand systems. The three labile aqua ligands on the starting synthon fac-[Re(CO)3(H2O)3]+ can easily be substituted by a variety and/or combinations of ligands producing stable compounds and potential radiopharmaceuticals with many different characteristics. We focus on the fac-[Re(CO)3]+ moiety and related compounds by adopting the [2+1] approach. The solid state behaviour and the effects like the charge, the donor atoms and electron donating and withdrawing effects of the ligands coordinated to the metal are explored. The influence of the coordinated bidentate ligands on the rate of substitution by a variety of entering ligands in solution is also investigated. The aqueous kinetics of fac-Re(I) tricarbonyl complexes are virtually unexplored. We synthesized a water soluble complex which allowed us to evaluate the reactivity of a fac-Re(I) tricarbonyl type complexes in aqueous medium which is imperative for biomedical application. The first high pressure substitution kinetics on a fac-[Re(L,L’-bid)(CO)3(CH3OH)] complex are also reported here.
Werner Paschinger
University of Vienna, Austria
Title: Relations between crystal structures and physical properties in the ternary systems CexTySnz (T = Pd or Pt)
Time : 12:25-12:50
Biography:
Werner Paschinger stared his studies in chemistry and physics at the University of Vienna in 2005. In 2013 he received his Bachelor of Science (B.Sc.) and in 2014 his Master of Science (M.Sc.) both from chemistry working on intermetallic compounds and thermoelectric materials within the group of Prof. Rogl at the Department of Physical Chemistry. Since April 2014 he is doing his PhD within the MATFLEXEND project at the Institute of Materials Chemistry & Research under supervision of Prof. Bismarck.
Abstract:
Although hitherto still no phase diagrams exist for the ternary systems CexTySnz (T = Pd or Pt), several compounds of these systems are in the focus of interest due to a number of interesting physical properties. Up to now, they have mainly been characterized by their magnetic properties, but more recently attracted attention due to their possible application as thermoelectric materials. For example, the hybridization of the 4f state of the Ce atom with conduction electrons of T and Sn atoms in Ce3Pt3Bi4 and CeRu4Sn6 or Ce4Pt12Sn25 with complex structures gives rise to a large thermopower, which is one of the prerequisites for thermoelectric application. For a proper interpretation and understanding of physical properties, the knowledge of the compounds’ crystal structure is of high importance. Therefore the relation of physical properties to structural motives in both systems will be discussed and compared to each other. Furthermore, we will introduce the crystal structure of two novel ternary compounds, CePd3Sn2 and Ce3Pt4Sn6, derived by direct methods from X-ray single crystal data. Whereas CePd3Sn2 crystallizes in an orthorhombic structure, Ce3Pt4Sn6 seems to coexist in a monoclinic and orthorhombic modification. For the monoclinic structure an intrinsically defect growth pattern was found backed by high resolution TEM. Structural units intrinsic to the title systems will be compared as well as to other related defect structures.