Copper(i) iodide cluster-based lanthanide organic frameworks: synthesis and application as efficient catalysts for carboxylative cyclization of propargyl alcohols with CO2 under mild conditions

Abstract

Two metal–organic frameworks (MOFs), namely, [Dy₂Cu₄I₄(NA)₆(DMF)₂]_n (1) and [Gd₂Cu₂I₂(IN)₆(DMF)₄]·5DMF (2) (HNA = nicotinic acid, HIN = isonicotinic acid), constructed based on lanthanide ions and copper iodide clusters ([Cu₄I₄] and [Cu₂I₂]) were successfully synthesized and characterized. Compound 1 has a three-dimensional framework and compound 2 displays a two-dimensional plane with sql topology, respectively. Both of them exhibit high thermostability and solvent stabilities. Additionally, catalytic explorations reveal that 1 displays higher catalytic activity than 2 for the carboxylic cyclization of propargyl alcohols. More importantly, 1 also exhibits excellent catalytic performance in the carboxylation reactions of CO₂ and terminal propargylic alcohols with various substituents. To the best of our knowledge, this is the first example of non-noble metal based MOF catalysts for the carboxylative cyclization of propargyl alcohols with CO₂ under atmospheric pressure and at room temperature, which provides a highly promising approach for MOFs in the catalytic conversion of CO₂ to valuable chemicals.