Anchoring Ag(I) into Nitro-Functionalized Metal–Organic Frameworks: Effectively Catalyzing Cycloaddition of CO2 with Propargylic Alcohols under Mild Conditions

Carboxylative cyclization of propargylic alcohols with CO 2 is significant in synthetic chemistry, but harsh conditions are often needed according to reported results. Herein, a new stable nitro-functionalized metal–organic framework (MOF) of {[Co 3 (L) 2 (bpy) 4 (H 2 O) 2 ]·DMF·H 2 O·bpy} n ( 1 ) was fabricated through the solvothermal reaction, which exhibited excellent stability in acid and basic solutions. Owing to the porous structure, unsaturated metal sites, and uncoordinated 4,4′-bpy ligands, 1 can serve as an excellent platform for catalytic applications. Hence, Ag(I) ions were incorporated in 1 through a postsynthetic method, and the as-synthesized Ag- 1 catalyst with low metal loading (0.64 mol %) displayed excellent catalytic performance in the chemical fixation of CO 2 with alkynols under room temperature and atmospheric pressure. The results of 1 H NMR analyses further confirmed that Ag- 1 can efficiently activate hydroxyl groups and promote the reaction. Moreover, the turnover frequency (TOF) of the Ag- 1 catalyst can reach 262 h –1 in a short period of time, which is a high TOF value among the state-of-the-art MOF-based catalysts for catalyzing cycloaddition of CO 2 with propargylic alcohols.