Ambient Chemical Fixation of CO2 Using a Robust Ag27 Cluster‐Based Two‐Dimensional Metal–Organic Framework

• Published in: Angewandte Chemie International Edition 2020-11, Vol.59 (45), p.20031-20036
• Main Authors: Zhao, Meihua, Huang, Shan, Fu, Qiang, Li, Weifeng, Guo, Rui, Yao, Qingxia, Wang, Fenglong, Cui, Ping, Tung, Chen‐Ho, Sun, Di
• Format: Article
• Language: English
• Subjects: 2D metal–organic frameworks; Alkynes; Carbon dioxide; Carbon dioxide fixation; Carbon sequestration; Catalysts; Catalytic activity; Clusters; CO2 fixation; Density functional theory; heterogeneous catalysis; Lewis acid; Metal-organic frameworks; Porphyrins; Robustness; Silver; silver cluster-assembled materials; Substrates; Two dimensional materials
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202007122

Unprecedented double S2− templated Ag27 clusters have been stabilized by 5,10,15,20‐tetra(4‐pyridyl)porphyrin (TPyP‐H2) ligands to afford a robust 2D metal–organic framework (Ag27‐MOF). This silver cluster‐assembled material serves as a highly efficient heterogeneous catalyst for the cyclization of both terminal and internal propargylamines with CO2 under atmospheric pressure. Density functional theory (DFT) calculations illustrate that the high catalytic activity and broad substrate scope are attributable to the saddle‐shaped metallic node in Ag27‐MOF, which features an accessible platform with high‐density silver atoms as π‐Lewis acid sites for activating C≡C triple bonds. As a result, different sterically hindered alkyne substrates can be effectively activated through π‐interactions with these cationic silver centers. An Ag27 cluster‐assembled 2D MOF has been constructed and employed as the catalyst for carboxylative cyclization of propargylamines with CO2. Both the high TON number and broad substrate scope confirm Ag27‐MOF to be an excellent heterogeneous catalyst, making a breakthrough in the use of 2D MOFs as high‐performance catalysts.