Chiral Phosphoric Acids in Metal–Organic Frameworks with Enhanced Acidity and Tunable Catalytic Selectivity. (5th September 2019)

• Record Type: Journal Article
• Authors: Chen, Xu; Jiang, Hong; Li, Xu; Hou, Bang; Gong, Wei; Wu, Xiaowei; Han, Xing; Zheng, Fanfan; Liu, Yan; Jiang, Jianwen; Cui, Yong
• Is Part Of: Angewandte Chemie. Volume 131:Number 41(2019)
• Page Start: 14890
• Page End: 14899
• Publication Date: 2019-09-05
• Subjects: Asymmetrische Katalyse -- Brønsted-Säuren -- Metall-organische Gerüstverbindungen -- Phorsphorsäure -- Porosität; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201908959
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Chiral phosphoric acids are incorporated into indium‐based metal–organic frameworks (In‐MOFs) by sterically preventing them from coordination. This concept leads to the synthesis of three chiral porous 3D In‐MOFs with different network topologies constructed from three enantiopure 1, 1′‐biphenol‐phosphoric acid derived tetracarboxylate linkers. More importantly, all the uncoordinated phosphoric acid groups are periodically aligned within the channels and display significantly enhanced acidity compared to the non‐immobilized acids. This facilitates the Brønsted acid catalysis of asymmetric condensation/amine addition and imine reduction. The enantioselectivities can be tuned (up to >99 % ee ) by varying the substituents to achieve a nearly linear correlation with the concentrations of steric bulky groups in the MOFs. DFT calculations suggest that the framework provides a chiral confined microenvironment that dictates both selectivity and reactivity of chiral MOFs. Abstract : Chirale Phosphorsäuren können durch sterische Hinderung ihrer Koordination in Metall‐organische Gerüste (MOFs) eingebaut werden. Das Resultat sind drei chirale poröse 3D‐In‐MOFs mit unterschiedlicher Netzwerktopologie aus drei von enantiomerenreiner 1, 1′‐Biphenolphosphorsäure abgeleiteten Tetracarboxylat‐Linkern.