Applied Crystallography

Biography

Biography: Alejandro Dorazco-González

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.