Boosting Catalytic Efficiency of Metal‐Organic Frameworks with Electron‐Withdrawing Effect for Lewis‐Acid Catalysis. Issue 30 (16th August 2021)

• Record Type: Journal Article
• Authors: Li, Siyu; Wang, Wenyang; Lei, Shengbin; Cui, Jian‐zhong
• Is Part Of: ChemistrySelect. Volume 6:Issue 30(2021)
• Page Start: 7732
• Page End: 7735
• Publication Date: 2021-08-16
• Subjects: Catalysis -- Knoevenagel reaction -- Lewis acid -- MIL-101(Fe); Chemistry -- Periodicals; 540.5
• DOI: 10.1002/slct.202101471
• Languages: English
• ISSNs: 2365-6549

Abstract

Abstract: Metal Organic Frameworks (MOFs) have the characterization of high specific surface area, abundant metal active sites and tunable pores, making them become emerging heterogeneous catalysts. Furthermore, the clear structure of MOFs provides an excellent opportunity to explore the internal relationship between catalytic activity and structure. In addition, precise synthesis of controllable catalytic sites from the molecular level can achieve efficient catalytic preparation of high value‐added chemicals. Here, we synthesize a series of MOFs (MIL‐101(Fe)‐X; X=H, NO2, Br, Cl) with different substituents on the terephthalate linker. Then the catalytic activity of MIL‐101(Fe)‐X was evaluated for Knoevenagel reaction with different substrates. The order of reactivity of MIL‐101(Fe)‐X is closely related to the ability of the electron withdrawing effect. The MIL‐101(Fe)‐NO2 showed the best conversion at low temperature (99.9 % at 25 °C). While the activity of pristine MIL‐101 only can reach 80.78 % of under same condition. This work illustrates the versatility of electronic effect on catalytic activity and brings possibility to tune the activity of MOFs through introducing organic ligands with different functional groups. Abstract : Five homogeneous MIL‐101(Fe)‐X nanostructures with different functional groups were prepared by a facile one‐pot method. When used as catalysts for the Knoevenagel reaction, the catalysts with functional groups of different electron‐absorbing groups have different reaction rates. This result is attributed to the introduction of different functional groups leading to different Lewis acidic strengths of the MOF nodes. This work suggests that modulating the electronic effect by introducing different organic ligands is an effective way to improve the catalytic performance of MOFs. It is predicted that more novel and effective MOF catalysts can be developed by modulating the organic ligands.