Relay catalysis of hydrocarbon oxidation using O2 in the confining domain of 3D metalloporphyrin-based metal-organic frameworks with bimetallic catalytic centers

To realize efficient and selective oxidation of hydrocarbons with O2, 3D MOFs possessing bimetallic centers were prepared to construct confining domains and relay catalysis sites. Applied to oxidation of hydrocarbons, optimum performance was observed in PCN-224(Co&Ni) as catalyst. Both of conversion and selectivity towards partial oxidation products were enhanced. In the significant cyclohexane oxidation, conversion increased from 5.89% to 7.26% with selectivity rose from 81.5% to 85.2%. Superior performance of PCN-224(Co&Ni) was attributed to suppressed free radical diffusion in confining domains of PCN-224(Co&Ni), enhanced oxidation of C-H bonds with oxidation intermediate R-OOH in relay catalysis, and decreased contact between partial oxidation products and catalytic centers. The relay catalysis mode and catalytic mechanism were also studied. The relay catalysis in confining domains herein provided a novel and effective strategy for selective and efficient oxidative functionalization of hydrocarbons, but also an intelligent and valuable idea for other chemical transformations involved free radicals.