Adenine-assisted synthesis of functionalized F-Mn-MOF-74 as an efficient catalyst with enhanced catalytic activity for the cycloaddition of carbon dioxide

The development of a highly efficient renewable heterogeneous catalysts for the synthesis of cyclic carbonates by the cyclic esterification of epoxides and carbon dioxide under relatively mild reaction conditions is of great significance in the territory of chemical fixation of carbon dioxide (CO2). This work comprises on a functional catalytic material F-Mn-MOF-74 using an effective competitive coordination strategy, adenine (Ad) as alkali source and competitive ligand, introduced onto the synthetic Mn-MOF-74. An F-Mn-MOF-74 crystal having a spherical structure and being functionalized is obtained, and lone pair of electrons on the nitrogen atom in the adenine can compete with 2,5-hydroxyterephthalic acid for coordination. The alkalinity exhibited by adenine is beneficial to enhance the catalytic properties of the crystal in the cycloaddition reaction of epoxide with carbon dioxide. Further catalytic experiments showed that the functionalized F-Mn-MOF-74 crystal combined with tetrabutylammonium bromide in the lacking of solvent showed excellent catalytic activity in the cycloaddition reaction of styrene oxide and carbon dioxide. Under the optimal reaction conditions after screening (100 degrees C and 10 bar CO2 pressure), the yield of cyclic carbonate was as high as 99 %. The excellent catalytic performance for other epoxides also confirmed that F-Mn-MOF-74 catalytic material is universal in its application. The catalytic performance of the catalyst was not significantly decreased after being recycled seven times, attributed to its excellent stability. The possible mechanism for the synergistic effect of Lewis acid-base properties of functionalized F-Mn-MOF-74 catalytic material with cocatalyst is also proposed.