Syntheses, Structure And Properties Of POM Based Compounds Constructed By Rigid Thiabendazole And Flexible Bis(pyrazole) Ligands

In this paper, self-assembly of Keggin, Wells-Dawson and Preyssler-type polyometalates(POMs)-based compounds decorated by transition metal-rigid/flexible organic subunits has been discussed systematically. The synthetic conditions and rules for the title compounds have been investigated. The influence factors of ligand flexibility(rigid/flexible), the length of the flexible ligands, varieties of POMs on the final structures have been further studied. The relationship between structures and properties for these compounds was also expolored.Through tuning synthetic conditions and reactants, fourteen new metal-organic coordination compounds based on different POMs have been synthesized under hydrothermal conditions, and structurally characterized by elemental analyses, IR spectra, and single crystal X-ray diffraction. Furthermore, the electrochemical and photocatalytic properties of these new compounds have also been studied.1. Using Keggin and Wells-Daswon type POMs as inorganic building blocks and rigid 2-(4-thiazolyl)benzimidazole(tbz) as an organic ligand, we designed, synthesized and characterized three new POM-based compounds:[CuII2Cl(tbz)4(PW12O40)]·3H2O(1)[CuII2(tbz)6(H2P2W18O62)]·6H2O(2)[ZnII(tbz)3]4[H(KPW12O40)3](3)Under similar synthetic conditions, the coordination modes of tbz ligands in compounds 1?3 show some differences by tuning the types of metal ions and POM anions, which result in obviously different structures of 1?3.2. By using Keggin, Wells-Daswon and Preyssler type polyoxometalates and flexible bis(pyrazole) ligands 1,1’-bis(3,5-dimethyl-1H-pyrazoleyl) methane(H2bdpm) and 1,2-bis(1H-pyrazol-yl)ethane(H2bhpe) containing different spacers, substituent groups, we synthesized nine new POM-based compounds:[Ag(H2bdpm)2(H2PW12O40)]·4H2O(4)[Cu(H2bdpm)2(H2PMo12O40)]·3H2O(5)[Ag(H2bdpm)2(H2PMo12O40)]?4H2O(6)[Ag6(H2bdpm)6(HPWVI8WV4O40)]·2H2O(7)[Ag4(H2bdpm)4(H2P2W18O62)]·3H2O(8)[Ag(H2bdpm)2Na2(H2O)3(HSi W12O40)]·3H2O(9)[(Ag H2bdpm)3(PW12O40)](10)[Ag13(H2bdpm)8(H2O)5(HAg P5W30O110)]·2H2O(11)[Ag3(Hbhpe)2(H2O)(H2PMo12O40)]·H2O(12)Although change the types of POMs and transition metal ions, three isomorphic compounds 4, 5 and 6 still obtained with the usage of the same ligand H2bdpm; By tuning the types of POM anions, we obtained five different structures of 7?11 with the using the same transition metal ions and H2 bdpm ligand; Meanwhile, when the organic ligand H2 bdpm was replaced by H2 bhpe, we obtained Kgeein-Ag based compound 12 with tri-nuclear silver clusters. We also explored the effect of substituent methyl in ligand on the multi-nuclear subunits.3. In the Keggin-Ag-tbz systems, assisted by the second ligands benzimidazole(bmz) and H2 bdpm, two Keggin-based compounds with mixed ligands were synthesized:[Ag6(tbz)4(bmz)2(HPWVI10WV2O40)]?4H2O(13)[Ag4(tbz)2(H2bdpm)2(HPMoVI10MoV2O40)]?2H2O(14)In the PW12-Ag-tbz system, part of tbz molecules were in situ decomposition with lost of thiazolyl group to form a benzimidazole ligand. Thereby a POM-based compound 13 containing hexa-nuclear Ag clusters constructed by mixed ligands was obtained; By using mixed rigid ligand tbz and flexible bis(pyrazolyl) ligand H2 bdpm, we successfully obtained a three-dimensional framework 14 including tetra-nuclear Ag cycles.In addition, the electrocatalytic behavior and potocatalytic degradation of methylene blue of some title compounds have been investigated. The results indicate that some compounds show good electrochemical and photocatalytic properties, which will act as potential inorganic-organic hybrid functional materials.