Synthesis And Properties Research Of Polyoxometalate Single Crystal Based On Phosphotungstate Anions

Eight new polyoxometalate compounds, on the basis of Dawson P₂W₁₈ anion or sandwich type PW₉ or P₂W₁5 polyoxoanion clusters, which are decorated or bridged by various transition or alkaline earth metal complexes, have been synthesized by hydrothermal technique and aqueous solution method.The chemical formulas of eight compounds have been determined by elemental analyses and TG analysis: [{Cu^I(imi)₂(H₂O)_Cu^II_0.5(imi)₂}{Cu^I(imi)₂}{Cu^II_0.5(imi)₂}(H₂P₂W₁₈O₆₂)_]·4H₂O (1) (Himi)₂[{Mn(2,2'-bpy)₂}₂(P₂W₁₈O₆₂)]·H₂O (2) (Himi)₂[{Cu(2,2'-bpy)₂}₂(P₂W₁₈O₆₂)]·H₂O (3) [Mn(phen)₃][{Mn(phen)₂(H₂O)}₂(P₂W₁₈O₆₂)]·3.5H₂O (4) [Cu(phen)₂Cl]₂[{Cu(phen)_H2O2}{Cu(phen)(en)}(P₂W₁₈O₆₂)_]·3H₂O (5) (H₂phen)_[Mn(phen)₃][{Mn(phen)_H2O3}(P₂W₁₈O₆₂)]·3.5H₂O (6) [{Sr(H₂O)₅Sr(H₂O)₆Sr_0.5(H₂O)₇}₂Mn₄(H₂O)₂(α-PW₉O₃₄)₂]·6H₂O (7) [{Sr(H₂O)₆Sr(H₂O)₈Sr(H₂O)₈Sr(H₂O)₄}₂Mn₄(H₂O)₂(αββα-P₂W₁₅O₅₆)₂]·5H₂O (8)These new compounds are structurally characterized by IR and single crystal X-ray diffractions. Compound 1 is 2D network which is composed of one [P₂W₁₈O₆₂]6- anion, one {Cu^I(imi)₂(H₂O)_Cu^II_0.5(imi)₂}²⁺ unit, two Cu^-imi units, and four water molecules. Each Cu atom and [P₂W₁₈O₆₂]^6- anion can be seemed as connecting nodes of 2D network. The adjacent [P₂W₁₈] units are connected by Cu-O-Cu bridges. Compound 2 and 3 are symmetrical infinitly liner chains which have the same structures. Adjacent [P₂W₁₈O₆₂]^6- anions are connecting with each other via two M(2,2'-bipy)₂ (M=Mn for 2, Cu for 3) complexes, forming four-supporting structures. Compounds 4, 5 and 6 represent 0D isolated structures. Compounds 1-6 are a serizes of organic-inorganic complexes and synthesized via adjusting pH value and changing ligands, noticing that it is available to control the product via change some circumstances under hydrothermal conditions. Compounds 7 and 8 are inorganic Mn-sandwich-type compounds which exhibit 3D frameworks based on the building blocks: trivacant lancrary Keggin and Wells-Dawson anions. Sr-O cluster are seemed as linkages to make the structures 14-modified, orming different topologies {4²⁰·6²⁸·8¹⁸}{4³}₄ and {4³}₂{4⁸·6⁶·8²⁷·12⁴}{4}2. It is vary rare that Sr-O clusters acting as connecting nodes.By electrochemical analysis system and cyclic voltammetric, electrochemical properties of the eight compounds were studied in detail. Additionally, the magnetic analysis of compound 2, 3, 7 are studied in detail. It is proved to be that antiferromagnetic interactions are found in 2, while ferromagnetic interactions are found in 3 and 7.