Structure And Properties Of Crown Ether Clathrate/triazole Carboxylic Acid Complexes

The reversible phase change materials have showed great potential applications in the field of switchable dielectric devices,data storage,sensing,signal processing etc.In addition,the complexes with multi-function or specific structure are of immense implementation prospect in adsorption,catalysis,luminescence,magnetism.In this paper,seven crown ether clathrates and four triazole carboxylic acid complexes were synthesized,X-ray single crystal diffraction,dielectric measurement,differential scanning calorimetry(DSC),fluorescence measurement were performed to research their structures,optical property and reversible phase transition.The main contents are as follows:A brief introduction of coordination chemistry and phase change materials are presented.Illustrate the research status of reversible phase change materials and triazole carboxylic acid complexes.The research significance and main results of this thesis are also summarized.Seven crown ether clathrates 1-7 were obtained by using 18-crown-6 as the stator,small organic amine molecules as the rotor and inorganic acid(perchloric acid,tetrafluoroboric acid,hexafluorophosphoric acid)as the auxiliary anion.The clathrates 1-2 displays unusual multisequential reversible phase transitions accompanied by switchable dielectric behaviors.The stepwise synergistic disordering of cations and anions leads to the sequential reversible phase transitions and symmetry breaking.The clathrate 3 reveals unusual two-step reversible structural phase transitions which consist of a ferroelastic phase transition and a special structural phase transition without symmetry breaking.Variable temperature X-ray single crystal diffraction disclose that the phase transitions are driven by two distinct rotation motions namely compass-like rotation and windlass-like rotation.The clathrates 4-7 possess reversible phase transitions in high temperature period.Clathrates 4-5 are crystallized in chiral space group and exhibit single chiral signal,what's more the clathrates 6-7 are crystallized in ferroelectric point group and have ferroelectric effect at room temperature.Four new metal-organic complexes 8-11 which synthesized from hydrothermal reaction are studied in this chapter.Transition metals(mainly d10 zinc and cadmium)coordinated with organic ligand methyl 1,2,4-triazole-3-carboxylate constructed these structures.Complexes 8-10 are analogous,only the substitution of metal ions,and the geometry of the central metal ions are hexacoordinated distorted octahedrons.Intermolecular hydrogen bonds and ?-? interaction connect the moieties to 3D frameworks in 8-10.The complex 11 have two coordination modes of metal ions and ligand molecules respectively,which resulted to a three-dimensional framework Solid-state fluorescence measurements indicated that complexes 8,10-11 have excellent green fluorescent properties.