Studies On The Post-functionalization Of Alkoxo Derivatives Of Hexavanadate And Their Properties

Polyoxovanadates?POVs?are an important subfield of polyoxometalates?POMs?.Due to the varying coordination mode and oxidation state of vanadium center,POVs possess diverse structures and unique electronic properties and have been widely applied and studied in the many fields,such as optics,electronics,magnetism,catalysis and drug research areas.Increasing researches have been focused on the organic modification of POVs via covalent bonding,because it not only could tune the properties of POVs themselves,but also may construct an organic-inorganic building blocks for further POM-based complexed system by connecting the organic and inorganic parts with their respective advantages.Based on the previous researches,we have synthesized a series of Lindqvist-type hexavanadate derivative-based organic-inorganic molecular hybrids using the molecular designing and post-functionalization by covalent bonding,and then we systematically studied the synthesis,structures,properties,self-assembly behavior and applications of these compounds.In brief,there are four parts in this work as follow:Firstly,amino-containing?n-Bu₄N?₂[V₆O₁₃{?OCH₂?₃CNH₂}₂]andcarboxyl-containing?n-Bu₄N?₂[V₆O₁₃{?OCH₂?₃CCOOH}₂]were synthesized using“pre-functionalization”and“post-functionalization”methods,respectively,and then structurally characterized.The functionalizations of hexavanadate clusters with amino or carboxyl groups make them good platforms for the further post-functionalization reactions.Secondly,a molecular triad nanorod Mo₆-V₆-Mo₆ constructed by covalently interlinking the above amino-containing hexavanadate derivative and hexamolybdates was synthesized using DCC?N,N'-dicyclohexylcarbodiimide?protocol and structurally characterized.The redox activity and photochromic behavior of triad nanorod were further studied.Thirdly,A special hybrid surfactant with a hexavanadate cluster as the polar head group and a long alkyl chain as the hydrophobic tail was synthesized by the single side alkylation reaction of amino-containing hexavanadate derivative.It was demonstrated that the hybrid surfactant could be spontaneously self-assembled into one-dimensional nanobelts,which is a highly efficient heterogeneous catalysts for the oxidation of organic sulfides and can be recycled easily.In addition,the freestanding POM-based coordination polymer nanosheets were synthesized using coordination reaction between carboxyl-containing hexavanadates and zinc ions by two different bottom-up methods.We further investigated the synthesis condition of nanosheets and its catalytic activity towards the aerobic oxidation reaction of propanethiol.Finally,five polyoxovanadate-based organic–inorganic hybrids were successfully synthesized via esterification of carboxylic acid groups-containing?n-Bu₄N?₂[V₆O₁₃{?OCH₂?₃CCOOH}₂]with five alcohols possessing differentfunctionalgroupsusingEEDQ?2-Ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline?as a coupling agent and then structurally characterized.The development of this synthetic procedure is of significance because the application of alcohols widens the range of substrates used in the functionalization of POM derivatives.Furthermore,we investigated the self-assembly behavior of hexavandate derivative modified by 1-hexadecanol as a special surfactant in the mixed solution.