Organically templated polar metal oxyfluorides

点击翻译按钮获取中文摘要

Several physical properties of solid compounds correlate with their crystal symmetry. E.g., piezoelectricity and second harmonic generation (SHG) are present only in non-centrosymmetric structures (point group 432 is also excluded); pyro- and ferroelectricity require crystallization in a polar space group type. The interesting properties and related potential applications of coordination polymers (MOFs) which are based on their porosity and huge internal surface could be combined with the mentioned electrooptic or dielectric properties if they could be crystallized in structures with the required symmetry restraints. The proposed project is intended to tackle this challenge by development of routes to non-centrosymmetric metal-organic solids. By supramolecular synthesis directional control of individual dipole orientations and formation of structures with long-range polarity is anticipated by incorporation of polar oxyfluoride groups [MOxFy]z- (M = V(V), Nb(V), Ta(V), Mo(VI), W(VI)) as metalloligands. Bridging organic ligands, mainly based on N-heterocycles, with functional groups will be designed in order to allow orientational control of the polar building blocks by exploiting supramolecular interactions such as hydrogen bonds, pi...pi stacking or anion...pi interactions. Anticipated results include the generation of new SHG, piezoelectric and ferroelectric materials with incorporated polar inorganic units as an origin of bulk polarity, synthesis and (structural) characterization of new complex oxyfluorides, development of tectons with combined functionalities for supramolecular synthesis and new routes for the preparation of novel metal-organic coordination compounds.