Metal–organic frameworks (MOFs) are an attractive catalyst support for stable immobilization of the active sites in their scaffold due to the high tunability of organic ligands. The active site-functionalized ligands can be easily employed to construct MOFs as porous heterogeneous catalysts. However, the existence of active sites on the external surfaces as well as internal pores of MOFs seriously impedes the selective reaction in the pore. Herein, through a simple post-synthetic ligand exchange (PSE) method we synthesized surface-deactivated (only core-active) core–shell-type MOF catalysts, which contain 2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) groups on the ligand as active sites for aerobic oxidation of alcohols. The porous but catalytically inactive shell ensured the size-selective permeability by sieving effects and induced all reactions to take place in the pores of the catalytically active core. Because PSE is a facile and universal approach, this can be rapidly applied to a variety of MOF-based catalysts for enhancing reaction selectivity.
Bibliographical noteFunding Information:
This work was supported by the Basic Science Research Program (2019R1A2C4070584) and the Science Research Center (2016R1A5A1009405) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT. S.K. and J.L. were supported by the NRF Global Ph.D. Fellowship program (S.K. for 2018H1A2A1062013; J.L. for 2019H1A2A1076014) funded by the Ministry of Education.
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- aerobic oxidation
- ligand exchange
- metal–organic frameworks
- post-synthetic modifications