A new supramolecular compound based on Keggin-type phosphomolybates with mixed-ligand and mixed-valence Cu(I/II): [Cu(I)(phen)2]2{[Cu(II)]2(phen)4PTA}[H3PMo8VIMo4VO40

Abstract

With an aim to obtain a new supramolecular compound based on Keggin-type polyoxometalates with mixed-ligand: [Cu(I)(phen)2]2{[Cu(II)]2(phen)4PTA}[H3PMoV4MoVI8O40] (phen = 1,10-phenanthroline, PTA = terephthalic acid) has been synthesized under hydrothermal conditions and structurally characterized by elemental analyses, IR, X-ray single crystal diffraction, TG analyses and XPS. In the title compound, the Keggin-type phosphomolybates anions, butterfly-shaped [Cu(I)(phen)2]+ subunits and dumbbell-shaped {[Cu(II)]2(phen)4PTA}2+ subunits are alternately connected to form chiral helical chains via hydrogen bonds along b axis, and the adjacent chiral helical chains are connected in the way of sharing butterfly-shaped [Cu(I)(phen)2]+ subunits and dumbbell-shaped {[Cu(II)]2(phen)4PTA}2+ subunits to form 3D supramolecular reticular framework. As expected, the title compound with mixed-ligands (phen and PTA) has been successfully synthesized, inconceivably, the title compound also contains mixed-valence Cu (Cu(I) in butterfly-shaped [Cu(I)(phen)2]+ subunits; Cu(II) in dumbbell-shaped {[Cu(II)]2(phen)4PTA}2+ subunits). The preliminary analyses show that mixed-valence Cu(I/II) may be due to the reduction of Cu(II) (from CuCl2) to Cu(I) (in butterfly-shaped [Cu(I)(phen)2]+ subunits) by N-containing compound. The successful results of this work provide a new idea that supramolecular materials with attractive structures and novel properties, which could be designed and synthesized by introducing of mixed-ligands into the supramolecular materials. Additionally, the electrocatalytic property of the title compound to H2O2 has been studied.