Two Robust Polyoxovanadate Clusters Having a Square-Prism V10Ox Core for Efficient Catalysis of Benzene Hydroxylation to Phenol

Abstract

Hydrogen peroxide (H2O2)-mediated oxidation of benzene to phenol in a single step is a promising approach for green phenol production. Nevertheless, it remains a long-sought pursuit to construct robust and efficient heterogeneous catalysts with atomic precision. Here we present the synthesis of two robust V10 oxo clusters holding different capping ligands: named V10-BTA, and V10-CBTA. Single crystal analysis reveals two decavanadate clusters exhibit a distinct braced square-prism configuration with different benzotriazole ligands capping on the edges of the square-prism, and V10-BTA is an example of rare highly reduced vanadium cluster. Accordingly, functionalization of the V10 square-prism with organic linkers both provides enhanced structural stability and introduces porosity to the cluster assembly in terms of heterogeneous application, thus allowing more active sites to be accessible and elevating reactivity. Remarkably, V10-BTA exhibits outstanding catalytic performance in the one-pot hydroxylation reaction, obtaining benzene to phenol conversion of 32.2% with a phenol selectivity of 99%, arising from the synergistic interplay between the braced square-prism configuration and the active V sites as confirmed by control experiments. Besides, V10-BTA displays broad substrate compatibility and superior recyclability for six successive cycles. This study provides an imperative strategy to develop POV clusters with excellent stability, while contributes to high catalytic efficiency for some challenging chemical transformations.