Imidazole-Dependent Assembly of Copper Polymolybdate Frameworks for One-Pot Sulfide Oxidation and C–H Activation

With the arising concern of environmental problems, the removal of polycyclic aromatic hydrocarbons or sulfides in fuel oils is an indispensable process to achieve a clean energy source. At present, direct catalytic oxidation of benzyl C–H bonds of polycyclic aromatic hydrocarbons and sulfides to corresponding carbonyl compounds is very attractive, yet their simultaneous oxidation using a single economical-friendly catalyst is not yet well established. Here, three imidazole-decorated copper polyoxomolybdate frameworks (Im-Cu-PMoFs) are successfully synthesized by tuning different imidazole derivatives. These Im-Cu-PMoFs can serve as effective heterogeneous catalysts for the one-pot oxidation of benzylic hydrocarbons and sulfides to produce carbonyl compounds. Specifically, Im-Cu-PMoFs-3 as a single component catalyst exhibits high activity and prominent selectivity (conversion up to 99% and selectivity up to 99%) in the one-pot reaction. In addition, the possible reaction pathway and active sites are supported by sufficient characterizations and DFT calculations, which reveal the synergistic effect of Mo(VI) and Cu(II) centers in the one-pot catalysis reaction. These dual function-validated frameworks hold much promise in the exploration of novel catalysts for applications like continuous catalytic or flow bed reaction.