Experimental and Theoretical Studies on Two Dual-Functional Organic–Inorganic Hybrids Based on [V4O12]4– Clusters

Two new bimetallic organic–inorganic hybrids based on [V4O12]4– polyanion, [Cu(dpy)(V2O6)]·H2O (1) and [Cu2(tpy)2(V4O12)] (2) [dpy = 2,6-di(pyrazol-1-yl) pyrazine; tpy = 4′-(pyrrol-3-yl)-2,2′:6′,2″-terpyridine], were synthesized under gentle solvothermal conditions. Hybrid 1 has a 1D {−V4O12–Cu2–V4O12}n circle-connecting-circle chain with [V4O12]4– clusters and [Cu(dpy)]2+ fragments, and hybrid 2 possesses a discrete structure assembled from [Cu2(tpy)]4+ motifs and [V4O12]4– clusters. We studied dual-functional electrocatalytic activities of the two hybrids for nitrite reduction and oxidation of ascorbic acid. Hybrid 1 shows superior electrocatalytic activity toward oxidation–reduction reactions with electrocatalytic efficiencies of 680 and 128%, respectively. Also, density functional theory calculations including the molecular electrostatic potential and the frontier molecular orbital were adopted to study the electron structure and charge distribution.