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

Abstract

Two new bimetallic organic−inorganic hybrids based on [V 4 O 12 ] 4− polyanion, [Cu(dpy)(V 2 O 6 )]•H 2 O (1) and [Cu 2 (tpy) 2 (V 4 O 12 )] (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 {−V 4 O 12 − Cu 2 −V 4 O 12 } n circle-connecting-circle chain with [V 4 O 12 ] 4− clusters and [Cu(dpy)] 2+ fragments, and hybrid 2 possesses a discrete structure assembled from [Cu 2 (tpy)] 4+ motifs and [V 4 O 12 ] 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.