Construction\nof Cobalt-Containing Polyoxovanadate-Based\nInorganic–Organic Hybrids as Heterogeneous Catalysts for the\nSelective Oxidation of Sulfides

In order to develop efficient catalysts for the selective\noxidation\nof sulfides, in this work, two polyoxovanadate-based inorganic–organic\nhybrids, [Co(H<sub>2</sub>O)<sub>3</sub>(3–bpfb)<sub>0.5</sub>(V<sub>2</sub>O<sub>6</sub>)]·(3–bpfb)<sub>0.5</sub> (<b>1</b>) and [Co(H<sub>2</sub>O)<sub>2</sub>(4–bpfb)<sub>0.5</sub>(V<sub>2</sub>O<sub>6</sub>)] (<b>2</b>) [3–bpfb\n= <i>N, N’</i>–bis(3–pyridylformamide)–1,\n4–benzenediamine, 4–bpfb = <i>N, N’</i>–bis(4–pyridylformamide)–1, 4–benzenediamine],\nwere isolated under hydrothermal conditions. The structures of <b>1</b> and <b>2</b> embodied two kinds of different cobalt-containing\npolyoxovanadate-based inorganic chains. Compound <b>1</b> contained\na one-dimensional inorganic zigzag chain created by the aggregation\nof {V<sub>2</sub>O<sub>6</sub>} clusters with each other, on which\nCo (II) ions were fixed. But it was an inorganic dimeric chain constructed\nfrom two linear {V<sub>2</sub>O<sub>6</sub>} cluster–based\nchains gathered by Co (II) ions in <b>2</b>. The 3–bpfb\nand 4–bpfb ligands, as the bidentate linkers, coordinated with\ntwo Co (II) ions from adjacent chains to organize them into two-dimensional\nlayers. The hydrogen bonds made important contributions to the formation\nof supramolecular structures of the two compounds. The two compounds\nserved as heterogeneous catalysts and exhibited efficient activity\nfor the selective oxidation of sulfide to sulfoxide and could be reused\nat least six times without loss of catalytic activity and stability.