Quest for a Desolvated Structure Unveils Breathing Phenomena in a MOF Leading to Greener Catalysis in a Solventless Setup: Insights from Combined Experimental and Computational Studies

The crystal structure of the metal–organic framework (MOF), {Mn₂(1,4-bdc)₂(DMF)₂}_<i>n</i> (<b>1</b>) (1,4-bdcH₂, 1,4-benzenedicarboxylic acid; DMF, <i>N</i>,<i>N</i>-dimethylformamide), is known for a long time; however, its desolvated structure, {Mn₂(1,4-bdc)₂}_<i>n</i> (<b>1′</b>), is not yet known. The first-principles-based computational simulation was used to unveil the structure of <b>1′</b> that shows the expansion in the framework, leading to pore opening after the removal of coordinated DMF molecules. We have used <b>1′</b> that contains open metal sites (OMSs) in the structure in cyanosilylation and CO₂ cycloaddition reactions and recorded complete conversions in a solventless setup. The pore opening in <b>1′</b> allows the facile diffusion of small aldehyde molecules into the channels, leading to complete conversion. The reactions with larger aldehydes, 2-naphthaldehyde and 9-anthracenecarboxaldehyde, also show 99.9% conversions, which are the highest reported until date in solventless conditions. The <i>in silico</i> simulations illustrate that larger aldehydes interact with Mn­(II) OMSs on the surfaces, enabling a closer interaction and facilitating complete conversions. The catalyst shows high recyclability, exhibiting 99.9% conversions in the successive reaction cycles with negligible change in the structure. Our investigations illustrate that the catalyst <b>1′</b> is economical, efficient, and robust and allows reactions in a solventless greener setup, and therefore the catalysis with <b>1′</b> can be regarded as “green catalysis”.