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) 4 PTA}[H 3 PMoV 4 MoVI 8 O 40 ] (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) 4 PTA}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) 4 PTA}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) 4 PTA}2+ subunits). The preliminary analyses show that mixed-valence Cu(I/II) may be due to the reduction of Cu(II) (from CuCl 2) 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 H 2 O 2 has been studied. Graphical abstract Unlabelled Image Highlights • Compound based on Keggin POMs with mixed-ligand and Cu(I/II) was prepared. • The compound contains the right- and left-hand helical chains. • The compound exhibits good electrocatalytic activity towards H 2 O 2 reduction [ABSTRACT FROM AUTHOR]