Systematic Engineering of Single Substitution in Zirconium Metal–Organic Frameworks toward High-Performance Catalysis
journal contributionposted on 2017-11-24, 00:00 authored by Ning Huang, Shuai Yuan, Hannah Drake, Xinyu Yang, Jiandong Pang, Junsheng Qin, Jialuo Li, Yingmu Zhang, Qi Wang, Donglin Jiang, Hong-Cai Zhou
Zirconium-based metal–organic frameworks (Zr-MOFs) exhibit great structural tunability and outstanding chemical stability, rendering them promising candidates for a wide range of practical applications. In this work, we synthesized a series of isostructural PCN-224 analogues functionalized by ethyl, bromo, chloro, and fluoro groups on the porphyrin unit, which allowed us to explicitly study the effects of electron-donating and electron-withdrawing substituents on catalytic performance in MOFs. Owing to the different electronic properties of ethyl, bromo, chloro, and fluoro substitutes, the molecular-level control over the chemical environment surrounding a catalytic center could be readily achieved in our MOFs. To investigate the effects of these substitutes on catalytic activity and selectivity, the oxidation of 3-methylpentane to corresponding alcohols and ketones was utilized as a model reaction. Within these five analogues of PCN-224, an extremely high turnover number of 7680 and turnover frequency of 10 240 h–1 was achieved by simply altering the substitutes on porphyrin rings. Moreover, a remarkable 99% selectivity of the tertiary alcohol over the five other possible by-products are realized. We demonstrate that this strategy can be used to efficiently screen a suitable peripheral environment around catalytic cores in MOFs for catalysis.
turnover frequencyporphyrin unitporphyrin ringschemical stabilitySystematic Engineeringselectivityisostructural PCN -224 analogues functionalizedMOFfluoro substitutesfluoro groupschemical environment10 240model reaction3- methylpentaneturnover numberSingle Substitutionchlorobromoelectron-withdrawing substituentsmolecular-level control