Assembly And Properties Of Copper Complexes Based On Polyoxometalates And Flexible/rigid Polyazole Ligands

In this paper, eight new functional complexes based on copper-flexible/rigid organonitrogenligands and structure-oriented by classical Keggin-type polyanions and [MO₈O₂6]^4-anion, havebeen synthesized under hydrothermal conditions and structurally characterized by elementalanalyses, IR, TG, XPRD, and single crystal X-ray diffractions. The electrochemical properties,the magnetic properties and photocatalytic properties of these compounds have been studied.1. Three new inorganic-organic hybrid complexes structure-oriented by three kinds ofpolyoxometalate anions have been hydrothermally synthesized by using the flexible bis（tetrazole）as organic ligands and copper ions as central metal ions. The influence of different kinds ofpolyoxometalates on crystal structures has been discussed:[Cu（bmte）（H₂MO₈O₂6）0.5]·3H₂O （1）[Cu₃（bmte）₃(HSiMo₁₂O₄₀)]· H₂O （2）[Cu₃（bmte）₃(HGeMo₁₂O₄₀)]· H₂O （3）bmte=1,2-bis（1-methyl-5-mercapto-1,2,3,4-tetrazole）ethaneIn compound1, two bmte ligands chelate two CuIions with three N atoms to form a binuclearnano-scale subunit [Cu₂（bmte）₂]²⁺, then the binuclear [Cu₂（bmte）₂]²⁺subunits are connected by[MO₈O₂6]^4-anions to build a one dimensional （1D） chain. In compound2, a trinuclear nano-scalesubunit [Cu₃（bmte）₃]3+constructed from three CuIions and three bmte ligands has been obtained,and the adjacent trinuclear subunits are linked by [SiMo₁₂O₄₀]^4-anions to form a “zipper”1Dchain. The adjacent chains of the title compounds are ultimately extended into2D layers byhydrogen bonds between bmte and [SiMo₁₂O₄₀]^4-anions. In compound3, because the GeMo12polyanion has the similar size and charge to SiMo12anion, compounds3and2are isostructural.The structural difference of the three compounds indicates that the POMs play an importantstructure-directed role in the construction of the final networks.2. Two new copper complexes structure-oriented by Keggin-type SiMo₁₂O₄₀4-andSiW₁₂O₄₀^4-anions have been hydrothermally synthesized on the basis of the rigid benzotriazole ligand:[CuI₈（BTA）₄（HBTA）₈(SiMo₁₂O₄₀)]·2H₂O （4）[CuⅡ₆（OH）₄（BTA）₄(SiW₁₂O₄₀)（H2O）₆]·6H₂O （5）HBTA=1-H-1,2,3-benzotriazoleIn compound4, eight CuIions were linked by twelve HBTA/BTA ligands to form anoctanuclear CuIcluster, which is connected by SiMo12O404-anion with two bridging O atoms andtwo terminal O atoms to construct a one-dimensional （1D） wave-like chain. The octanuclearcopper unit represents the maximum subunit linked just by amine ligands in POMs system. In5,four BTA ligands linked five CuⅡions constructing a pentanuclear “porphyrin-like” subunit,which is connected by another CuⅡion to form a1D metal-organic band. The SiW₁₂O₄₀₄-polyanions as tetradentate inorganic linkages extend the1D band into a two-dimensional （2D）network with （83）2（85·10） topology. To the best of our knowledge, compounds4and5representthe first examples of inorganic-organic hybrids based on metal-HBTA multinuclear subunits andpolyoxometalates.3. Three new metal-organic complexes structure-oriented by Keggin-type anions have beenhydrothermally synthesized by introducing rigid benzimidazole and its derivative ligands into thesystem:[CuⅡ2（biz）₈(PMoVI₁₁MoVO₄₀)（H₂O）₂]· H₂O （6）[CuI₄（biz）₈(SiW₁₂O₄₀)]· H₂O （7）biz=benzimidazole[CuI₂（dmbiz）₄（Hdmbiz）(HSiW₁₂O₄₀)]（8）dmbiz=5,6-dimethyl benzimidazoleIn compound6, two kinds of metal-organic CuⅡunits linked with four PMo12O403-and eachPMo12O403-anion connected with eight metal-organic unit through hydrogen bondinginteraction, leading to the formation of （4,8）-connected3D supermolecular framework. Incompound7, we selected SiW₁₂O₄₀₄-as inorganic ligand, and the final structure is6-connected3D superamolecular network, which was linked not noly by hydrogen bonds interactions butalso by weak Cu···O interaction. Compound8is a3D superamolecular framework with NaCltype structure, in which dmbiz was used as organic amine ligand instead of biz.4. In this thesis, the directional assembly of such functional complexes oriented by polyoxometalates under hydrothermal conditions has been realized. The influence of systemfactors of the assembly processes, including the pH value, temperature, reaction time of thesystem, the type of polyoxometalate and the reactant ratio etc., on the construction of targetcomplexes has been explored. In addition, the electrochemical behavior, magnetic property andpotocatalytic degradation methylene blue performance of some title compounds have beeninvestagated. The results indicate that some compounds show good property and will become thepotential inorganic functional materials.