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

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.