Synthesis And Characterization Of Amphiphilic Organic-inorganic Hybrid Materials Based On Polyoxovanadates

Polyoxometalates(POMs)are a kind of inorganic clusters formed by pre-transition metal ions and bridging oxygen atoms.POMs have unique structures and physical and versatile chemical properties and have attracted continuous attention from researchers.As a kind of nanosize inorganic metal salt,POMs have high surface charge and good solubility in water.The combination of POMs and hydrophobic organic ligands will result in amphiphilic inorganic-organic hybrid molecules,which have potential applications in the fields such as phase-transfer catalysis and liquid crystal materials.This research have introduced different hydrophobic organic ligands into the polyoxovanadate system using different synthetic strategies to build amphiphilic hybrid molecules.The structures of the products have been characterized and their optical and wetting properties have also been studied.The main research contents and results are as follows:1.A series of amphiphilic hybrid molecules based on hexavanadate have been synthesized by covalently attaching benzoic ligands with long alkyl chains onto the trialkoxyl-derived hexavanadates.The products have been structurally characterized and the hydrophobic properties and morphology of the products were studied.The effect of alkyl chain length and numbers on the crystallization,assembly and physicochemical properties of the hybrid molecules were also discussed.2.A series of amphiphilic polyoxovanadate hybrid molecules with optical properties were syntheized by grafting conjugated organic photosensitizers onto Lindqvist-type hexavanadate.The structures of the products have been confirmed by single crystal XRD tests and other characterizations.The optical properties of these hybrid molecules were studied by ultraviolet and fluorescence spectroscopy.The results show that optical properties of the organic ligands were retained after attaching onto the POM system.However,the electron transfer between POM cluster and photosensitive groups leads to the occurrence of fluorescence quenching.3.A new type of POM-based amphiphilic hybrid materials have been designed and synthesized by combining hexavanadate derivatives with p-iodobenzoic acid ligands,which were prepared by means of step-by-step modification,and pyridine ligands with long alkyl chains via halogen bonding interactions.Polarization microscopy results show that the amphiphilic hexavanadate molecule has a phase transition point at 80 ?,and its liquid crystal morphology can be clearly observed in a wide range of 80~180 ?.