Assembly of Cu/Ag-quinoxaline-polyoxotungstate hybrids: Influence of Keggin and Wells-Dawson polyanions on the structure

In order to investigate the influence of Keggin and Wells-Dawson polyoxometalates on the resultant structure, four new organic-inorganic hybrid compounds [Cu₄(qx)₅(SiW₁₂O₄₀)] (1), [Cu₆(qx)₆(P₂W₁₈O₆₂) (H₂O)_1.5]·4.5H₂O (2), [Ag ₄(qx)₄(SiW₁₂O₄₀)(H ₂O)]·H₂O (3), [Ag₆(qx) ₆(P₂W₁₈O₆₂)]·8H₂O (4) (qx=quinoxaline) were synthesized and structurally characterized by single-crystal X-ray diffraction. In 1, the 2D layers are linked by the SiW ₁₂O₄₀^4- (SiW12) anions to construct a 3D framework. When the Wells-Dawson type P₂W₁₈O ₆₂^6- (P2W18) is used, 2 is prepared, in which the 1D helical chains are connected by P2W18 to form a 3D network. In 3, two kinds of 1D metal-organic chains are connected by SiW12 clusters to construct a 3D framework. In 4, there are also two kinds of 1D chains one kind of 1D chain combines with P2W18 by the AgO weak interaction and the other kind is just metal-organic chain. In addition, the electrochemistry properties of compounds 1-4 have been studied.