Selectively Regulating Lewis Acid–Base Sites in Metal–Organic Frameworks for Achieving Turn‐On/Off of the Catalytic Activity in Different CO<sub>2</sub>Reactions
Xuerui Tian, Xiao‐Lei Jiang, Sheng‐Li Hou, Zhuo‐Hao Jiao, Jie Han, Bin Zhao
Abstract
Abstract Regulating Lewis acid–base sites in catalysts to investigate their influence in the chemical fixation of CO 2 is significant but challenging. A metal–organic framework (MOF) with open metal Co sites, {(NH 2 Me 2 )[Co 3 ( μ 3 ‐OH)(BTB) 2 (H 2 O)]⋅9 H 2 O⋅5 DMF} n ( 1 ), was obtained and the results of the catalytic investigation show that 1 can catalyze cycloaddition of CO 2 and aziridines to give 99 % yield. The efficiency of the cyclization of CO 2 with propargyl amines is only 32 %. To improve the catalytic ability of 1 , ligand XN with Lewis base sites was introduced into 1 and coordinated with the open Co sites, resulting in a decrease of the Lewis acid sites and an increase in the Lewis base sites in a related MOF 2 ({(NH 2 Me 2 )[Co 3 ( μ 3 ‐OH)(NHMe 2 )(BTB) 2 (XN)]⋅8 H 2 O⋅4 DMF} n ). Selective regulation of the type of active centers causes the yield of oxazolidinones to be enhanced by about 2.4 times, suggesting that this strategy can turn on/off the catalytic activity for different reactions. The catalytic results from 2 treated with acid solution support this conclusion. This work illuminates a MOF‐construction strategy that produces efficient catalysts for CO 2 conversion.