Synthesis, Crystal Structure And Properties Research Of Polyoxometalate Modified By Flxible Ligand Based On Phosphotungstate

Five novel inorganic-organic hybrid compounds based on Wells-Dawson orKeggin-type anion have been synthesized through selecting appropriate flexible organicligands and various transition metals to decorat or bridge POM under hydrothermalcondition. They are characterized by elemental analysis and TG. Their chemical typefor:（H₂bbi）₂{[Ag₂（bbi）_1.5](P₂W₁₈O₆₂)}（1）（H₂bbi）₂[Ag_0.5（bbi）][Ag_0.5（eim）₂][P₂W₁₈O₆₂]·H₃O·H₂O （2）[Cu₃（bbi）₆(P₂W₁₈O₆₂)]（3）[Cu（bpp）₂][Cu0.5（bpp）]2[PWⅥ9WⅤ3O₃₉]（4）（Hbpp）[{Cu（Hbpp）₂}(PW₁₁CuO₃₉)]·H₂O（5）(bbi=1,1’-(1,^4-butanediyl)bis（imidazole），bpp=1,3’-Di(^4-pyridyl)propane，eim=ethyl（imidazole）)These new compounds are structurally characterized by IR and single crystal X-raydiffractions. Single-crystal X-ray structural analysis reveals that the framework ofcompounds1consists of one [P₂W₁₈O₆₂]^6-anion, one [Ag₂（bbi）_1.5]²⁺and two adouble-proton of bbi ligand structure unit. The[Ag₂（bbi）_1.5]²⁺fragment formed infinite1D stepped shaped chain alternating connection of a ring and chain. Adjacent[P₂W₁₈O₆₂]^6-anion are linked via two equatorial oxygen atom and Ag （1） to formdimeric unit. The dimeric units and1D chain further connect to form a strange of twodimension layer, which further bond together by equatorial oxygen atom to form threedimensional structure. Compounds2is composed of two double-protonated bbi ligandunit, a Ag_0.5（bbi）+cation, a Ag_0.5（eim）_<sup>2+cation, a [P₂W₁₈O₆₂]^6-anion, a protonated watermolecular and a free of water molecular, in which eim is in situ ligand from bbi.[P₂W₁₈O₆₂]^6-anion as template is connected with Ag-bbi chain in alternating ways alongvertical direction via supramolecular interaction to form a two dimension Supermolecular structure. In compound3, each Cu²⁺ion is connected with four adjacent Cu²⁺ions by bbi ligands along four different directions, which results in an unusual2Dinterlink lock-liked layer. Interestingly, the [P₂W₁₈O₆₂]^6-polyoxoanions as bidentate‘guest’ is incorporated into the lock chain to form complicated2D layer. Compounds 4is composed of [PW₉^ⅥW₃^ⅤO₃₉]anion，[Cu（bpp）2]cation and [Cu0.5（bpp）]2cationcomplex. The basic unit [PW₉^ⅥW₃^ⅤO₃₉]^4-anion link up each other via O（15） to form1-D chain in-A-B-A-B-manner. The chains are further bonded up via supramolecularinteraction to form2-D layers. Compounds5consists of one [PW₁₁CuO₃₉]^5-anion, one[Cu（Hbpp）₂]⁴⁺segment, a protonated bpp ligand, and a dissociative water molecular.Each [PW₁₁CuO₃₉]^5-anion is bonded up via O（27） to form1-D chain.[Cu（Hbpp）2]4+complex looks like two arms and also connects to polyanion alongvertical direction to form an unique1-D structures. The chains are further bonded up viasupramolecular interaction to form special wave-liked2-D layers.The elecrrochemical properties of the five compounds are studied in detail byelectrochemical analysis system and cyclic voltammetric. And the electrocatalyticReduction analysis of the compounds are studied in detail. They all exhibit goodelectrocatalytic activity to reduce H₂O₂.