Assembly And Properties Of Keggin-type Polyoxometalatcs-based Complexes Decorated By Transition Metal-Rigid/Flexible Organic Subunits

In this paper, the chemical assembly of Keggin-type polyoxometalates (POMs)-based complexes decorated by transition metal-rigid/flexible organic subunits has been disscused systematicly. The synthetic conditions and rules for the title compounds have been investigated. The influences of the ratio of organic ligands to transition metal ions, the length of the flexible ligands, the varieties of POMs on the final structures have been studied. The relationship between structures and properties for these compounds are also reported.Twelve new metal-organic coordination complounds based on classical Keggin-type POMs have been synthesized under hydrothermal conditions, and structurally characterized by elemental analyses, IR, TG, single crystal X-ray diffractions and X-ray powder diffractions. The electrochemical properties and photochemical catalysis of these new compounds have also been studied. The results are as follows:1. Using Keggin-type POMs as inorganic building blocks and rigid pdon as organic ligand, we designed, synthesized and characterized three new POM-based coordination compounds:[Cu2pdon3][PMoVI11Mov040]-3H2O (1)[Mn2Cl(H2O)2pdon4][PMo12O4o]-H2O (2)[Cu3(μ2-OH)(pdon)3(pca)(H2O)3][SiW12O40]-6H2O (3)By tuning the ratio of the metal salt to organic ligand, the coordination modes of pdon ligands in compounds1and2show huge differences, which result in obviously different structures of1and2. In3, the organic ligand shows an in situ transformation, and two types of one dimensional helical chains were obtained.2. By tuning the spatial lengths of organic ligands and the type of POMs in Cu-bis(tetrazole) thioether and Keggin systems, we synthesized five new POM-based coordination compounds:[CuI2(bmtm)3]2?[CuI2(bmtm)4]-(PW12O40)2(4)[CuI3(bmte)3(PW12O40)](5) [CuI3(bmtr3(PW12O40)](6)[CuI2(bmtm)3]2?[CuI2bmtm]4?(PMo12O40)2(7)[CuI12(bmtr)9(HSiMo12O40)4](8)There is an obvious difference among the final structures of4,5and6by changing the spatial lengths of organic ligands. Meanwhile, when [PW12O40]3-is replaced by [PMo12O40]3-anion, the structure is kept unchanged. Using [SiMo12O40]4-, we obtained compound8with a very different structure from6.3. Four new Ag1complexes based on Keggin-type [SiMo12O40]4-have been synthesized, through using1-methyl-5-mercapto-1,2,3,4-tetrazole and its derivatives bis (tetrazole) thioethers as organic ligands:[Ag6Cl2(mmt)4(SiMo12O40)(H2O)2](9)[Ag4(bmte)2(H2O)2(SiMo12O40)](10)[Ag4(bmtr)2(H2O)2(SiMo12O40)](11)[Ag4(bmtb)3(SiMo12O40)](12)The introduction of alkyl chains makes central metal ions be centralized together with ease, which is the crucial factor for construction of multinuclear metal-organic subunits. The similar multinuclear subunits haven’t appeared in compound9with mercapto tetrazole ligand. The final structures of10,11and12have big differences owing to the different lengths of ligands.In addition, the electrocatalytic behavior and potocatalytic degradation methylene blue performance of some title compounds have been investigated. The results indicate that some compounds show good property and will become the potential inorganic-organic hybrid functional materials.