Designing a Polyoxometalate-Incorporated Metal–Organic Framework for Reduction of Nitroarenes to Anilines by Sequential Proton-Coupled Electron Transfers
Si Chen, Fan Liu, Xiaomei Yan, Jiangbo Xu, Guiqin Niu, Qiuxia Han
Abstract
Developing new photocatalysts for reduction of nitroarenes to anilines under mild conditions is very significant. Herein, a new polyoxometalate-based metal–organic framework (POMOF), {[Co(H2O)]2[Co2(H2O)6(TPT)][Co(TPT)PW11O39]}·3H2O·TPT (namely, CoW-TPT, TPT = 2,4,6-tri(4-pyridyl)-1,3,5-triazine), was prepared by incorporating Co(II)-substituted Keggin-type anions [PCoW11O39]5– and a photosensitizer (TPT) into a framework. In this structure, the direct coordination bond between [PCoW11O39]5– and TPT ligand and π···π interactions between TPT molecules are beneficial for the separation and migration of photogenerated carriers, thus improving the photocatalytic activity of CoW-TPT. The combination of both photosensitizer TPT and the electron-storable component [PCoW11O39]5– in a cooperative photocatalysis fashion is conducive to the photocatalytic multielectron reduction of nitroarenes. CoW-TPT provided a high conversion of 94.71% in the photocatalytic reduction of nitroarenes to anilines utilizing triethanolamine as the proton source and electron donor by sequential proton-coupled electron transfers.