Cyano-bifunctional MOFs as superior catalysts for carbon dioxide fixation under co-catalyst and solvent free conditions

Abstract

In the present work, a strategy for the incorporation of nitrogen-rich units to an unsaturated Cr-based MOF, MIL-100-Cr, is reported. Based on this strategy, various cyanide functional groups (diamino malononitrile, 1,3-phenylene diacetonitrile, and malononitrile) were incorporated into the framework and utilized as exceptional catalysts in the carbon dioxide fixation under mild, solvent, and co-catalyst free conditions. This is the first report on the application of cyano-bifunctional frameworks in cycloaddition reaction. The contemporaneous presence of accessible Lewis acid sites and pendent cyanide groups results in highly striking conversion and TON even for bulky and large substrates. High tendency and strong interaction of cyanide groups with CO2 cause a synergetic effect in the performance of the catalysts. The role of different cyanide groups applied in this work has also been studied. The reaction wouldn’t proceed in the presence of pristine MOF without co-catalyst addition.