Day 1 :
Keynote Forum
Gerd Kaupp
University of Oldenburg, Germany
Keynote: Crystal structure and organic solid-state reactions
Time : 10:00-10:40
Biography:
Gerd Kaupp has completed his PhD at the age of 24 years from Würzburg University and postdoctoral studies from Iowa State, Lausanne, and Freiburg University. He held a full-professorship till 2005 in Oldenburg, Germany, and he privately continues his research on solid-state reactions, AFM on rough surfaces (since 1988), the as yet better resolving sub-diffraction limit microscopy also for non-fluorescing materials, even rough ones, of all types (resolution <10 nm, since 1995), and nano-indentations (since 2000). He has published more than 300 papers in renowned journals and has been serving as an editorial board member of several scientific journals.
Abstract:
Crystal structures of organic solid-state reactions are decisive for their occurrence and selectivity. While Schmidts topochemistry concentrates on a distance limit between reacting centers by denying molecular migrations within the crystal, too many positive and negative failures pose unsurmountable problems for predictions. Conversely, AFM, SNOM, GID, and nano-scratching indicate anisotropic molecular migrations, enforced by the internal pressure upon chemical change by reaction that requires release. This holds for intra- and inter-crystalline and for gas-solid reactions also with formerly "too large" distances, explains nonreactivities at very small distances, and intercrystalline reactions. Required are crystallographic possibilities for molecular migrations within slip-planes and channels, or to sufficiently wide crystallographic voids. Such migrations are anisotropic and they are face-specific. Slip-planes or channels end on the reactive crystal faces, not on the unreactive ones. For intracrystalline reactions molecules move out and for intercrystalline ones reactants move also in. Solid-state reactions profit from the bargain of favorable crystallinity with respect to the same melt reactions (the latter require up to about 100K higher temperature and are less selective). This opposes undue beliefs that solid-state reactions require melts, or claims that these should require "help by some solvent". Such widely proposed beliefs restrict to reactions that proceed around room temperature as liquid-state reactions, mostly loosing completeness and/or specificity. In the case of non-reactive polymorphs one may try to generate and use different modifications. The pseudo-problems of topochemistry are easily removed by applying the full structural content. New applications for molecular and polymer (including large-scale) chemistry ensue.
Keynote Forum
Jurg Hulliger
University of Berne, Switzerland
Keynote: Orientational Disorder of Dipolar Molecules: a Key to understand Polarity Formation in Materials
Time : 11:00-11:40
Biography:
Jurg Hulliger studied physical chemistry at ETH Zürich and received a PhD from the University of Zürich. Later he moved to the Department of Physics at ETH Zürich to perform research on materials and crystal growth. Since 1993 he has been a full professor at the University of Berne. His research interests cover materials synthesis, physical properties and theory of condensed matter. Since 2004 he has been a fellow of the Royal Society of Chemistry. The present topic is represented by about 80 peer reviewed papers.
Abstract:
Dipolar molecules (low molecular weight up to macromolecular) entering solid matter by a mechanism of growth can produce macroscopic effects of polarity. Here, we will review theoretical and experimental results on a stochastic mechanism leading to polarity in molecular crystals, inorganic-organic biomimetic materials and natural tissues. Monte Carlo model and molecular dynamics simulations support a so called bi-polar state in all these cases. The bi-polar state is characterized by two adjacent polar domains of opposite orientation of the polarization.rnExperimentally, the spatial distribution of polarity in materials was investigated by scanning pyroelectric (SPEM) and phase sensitive second harmonic generation microscopy (PS-SHG). These two advanced techniques allowed us for the first time to demonstrate the theoretically predicted reversal transition in molecular crystals nucleating into a polar structure, developing then two adjacent domains of opposite polarization. Similarly, PS-SHGM was applied to a first determination of the absolute polarity distribution in teeth cementum.rnTheoretical and experimental work on various materials allow us to conclude, that in general a bi-polar state represents the statistical ground state of materials made of dipolar constituents. For further introduction, see review by J. Hulliger et al., New J. Chem., 37, 2229-2235, 2013. Theoretical issues may be recovered from J. Hulliger et al., Cryst. Growth Des., 12, 5211-5218, 2012.rn
- 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.