Synthesis, structural characterization, encapsulation in zeolite Y and catalytic activity of an oxidovanadium(V) complex with a tribasic pentadentate ligand

Reaction of [VIVO(acac)2] with H3hap-dahp (I: Schiff base derived from 2-hydroxyacetophenone and 1,3-diamino-2-hydroxypropane) in methanol under aerobic conditions resulted in the formation of the complex [VVO(hap-dahp)] (1). Treatment of I with vanadium(IV) exchanged zeolite Y followed by aerial oxidation gave the encapsulated oxidovanadium(V) complex [VVO(hap-dahp)]-Y (2) in the nanocavity of zeolite Y. Elemental analysis, spectroscopic (IR, electronic, 1H and 51V NMR) studies, scanning electron micrographs and X-ray diffraction patterns have been used to characterize these complexes, which have a distorted octahedral structure, confirming the tribasic O3N2 binding mode of the ligand. The encapsulated complex [VVO(hap-dahp)]-Y (2) catalyzes the oxidation of styrene, methyl phenyl sulfide and diphenyl sulfide using H2O2 as an oxidant in good yield (82%, 98% and 81%, respectively). Styrene, under optimized reaction conditions, gave five reaction products, namely styrene oxide, benzaldehyde, 1-phenylethane-1,2-diol, benzoic acid and phenylacetaldehyde, while the organic sulfides gave the corresponding sulfoxides as the major product. The neat complex [VVO(hap-dahp)] (1) also exhibits good catalytic activity for these substrates. The encapsulated complex showed a good recycling ability.

Graphical abstractAn oxidovanadium(V) complex with a tribasic pentadentate ligand has been synthesized and encapsulated in the nanocavities of zeolite Y. Its characterization and catalytic activity for the oxidation of styrene, methyl phenyl sulfide and diphenyl sulfide using H2O2 as the oxidant has also been reported.Figure optionsDownload full-size imageDownload as PowerPoint slide