In Situ Ligand-Transformation-Involved Synthesis of Inorganic–Organic Hybrid Polyoxovanadates as Efficient Heterogeneous Catalysts for the Selective Oxidation of Sulfides

By intentionally involving in situ ligand transformation in the reaction system, two inorganic–organic hybrid polyoxovanadates (POVs), [Co(HDTBA)V2O6] (1) and [Ni(H2O)2(DTBA)2V2O4(OH)2]·4H2O (2), have been synthesized by using a hydrothermal method, where the 3,5-di[1,2,4]triazol-1-ylbenzoic acid (HDTBA) ligand originated from in situ hydrolysis of 3,5-di[1,2,4]triazol-1-ylbenzonitrile in the self-assembly process. The inorganic layers [Co2(V4O12)]n containing [V4O12]4– circle clusters were linked by HDTBA ligands to yield a 3D framework structure of compound 1. There existed a kind of binuclear [(DTBA)2V2O4(OH)2]2– vanadium cluster grafted directly by two DTBA ligands through the sharing of carboxyl oxygen atoms in compound 2, further extended into a 2D layer by nickel centers. The investigations on the catalytic properties indicated that compounds 1 and 2 as heterogeneous catalysts, especially 2, owned satisfying catalytic performances for catalyzing the selective oxidation of sulfides to sulfoxides in the presence of tert-butyl hydroperoxide as an oxidant, accompanied by excellent conversion of 100% and selectivity of above 99%, providing a promising way for developing inorganic–organic hybrid POVs as effective heterogeneous catalysts for catalyzing the selective oxidation of sulfides.