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

• 作者: Xu Chen Zhiwei Qiao Bang Hou Hong Jiang Wei Gong Jinqiao Dong Hai-Yang Li Yong Cui Yan Liu
• 来源期刊: 纳米研究（英文版）
• 年，卷（期）: 2021,（2）
• 所属期刊栏目: Research Articles
• 页码范围: 466-472
• 页数: 7页
• 语种: 英文

摘要

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-trimsthyl-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.