Improved olefin epoxidation performance of a discrete bis(8-quinolinol)oxovanadium(IV) complex covalently attached on SBA-15 by a metal-template/metal-exchange method

A metal-template/metal-exchange method was used for the covalent attachment of a discrete bis(8-quinolinol)oxovanadium(IV) complex onto mesoporous silica SBA-15 to obtain a heterogeneous catalyst VOIVT. For comparison, its homogeneous counterpart VOIVN and the randomly ligand-grafted heterogeneous analogue VOIVG were also prepared. UV–vis spectra of the VOIV catalysts show VOIVT adopts a more solution-like bis(8-quinolinol) coordination environment than VOIVG. Correspondingly, olefin epoxidation with tert-butyl hydroperoxide shows VOIVT has improved reactivity, epoxide selectivity and recyclability than VOIVN or VOIVG. The homogeneity of the discrete bis(8-quinolinol)oxovanadium(IV) complex immobilized on SBA-15 should be responsible for the superior performances of the templated catalyst.