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Nano Research

Article Title

Chiral metal-organic frameworks with tunable catalytic selectivity in asymmetric transfer hydrogenation reactions

Authors

Xu Chen, School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China
Zhiwei Qiao, Guangzhou Key Laboratory for New Energy and Green Catalysis, School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, China
Bang Hou, School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China
Hong Jiang, School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China
Wei Gong, School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China
Jinqiao Dong, School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China
Hai-Yang Li, Green Catalysis Center and College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001, China
Yong Cui, School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China
Yan Liu, School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China

Keywords

metal-organic frameworks, metal phosphonate, Lewis acid, asymmetric catalysis, hydrogenation reaction

Abstract

Metal-organic frameworks (MOFs) have achieved great success in the field of heterogeneous catalysis, however, it’s still challenging to design MOF catalysts with enhanced selectivity. Here, we demonstrated a combination strategy of metal design and ligand design on the enantioselectivity—that is the enantioselectivities of chiral MOF (CMOF) catalysts could be significantly enhanced by the rational choice of metal ions with higher electronegativities and introducing sterically demanding groups into the ligands. Four isostructural Ca-, Sr- and Zn-based CMOFs were prepared from enantiopure phosphono-carboxylate ligands of 1,1'-biphenol that are functionalized with 2,4,6-trimethyl- and 2,4,6-trifluoro-phenyl groups at the 3,3'-position. The uniformly distributed metal phosphonates along the channels could act as Lewis acids and catalyze the asymmetric transfer hydrogenation of heteroaromatic imines (benzoxazines and quinolines). Particularly, the Ca-based MOF 1 with 2,4,6-trimethyl groups at the substituents exhibited enhanced catalytic performance, affording the highest enantioselectivity (up to 97%). It is also the first report of the heterogeneous catalyst with chiral non-noble metal phosphonate active sites for asymmetric transfer hydrogenation reactions with Hantzsch ester as the hydrogen source. The catalyst design strategy demonstrated here is expected to develop new types of chiral materials for asymmetric catalysis and other chiral applications.

Publisher

Tsinghua University Press

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