Preparation of heterogeneous catalysts by the post-synthetic modification of mesoporous metal-organic framework MIL-101

A series of MIL-101-L compounds (L = 4,4 ' -bipyridyl, pyrazine, piperazine, 1,4-diaza[2.2.2]bicyclooctane, and ethylenediamine) was synthesized using the post-synthetic coordination modification of mesoporous chromium(iii) terephthalate MIL-101. These compounds contain basic sites and are capable of exhibiting catalytic activity in the Henry nitroaldol condensation reaction with high selectivity. Compounds MIL-101-Sal-M (M = Ni, Cr, Zr, Co) containing the salen complexes grafted onto the framework surface were prepared using the covalent post-synthetic modification methods. These compounds exhibit catalytic activity in the addition of carbon dioxide to propylene oxide in quantitative yield in the presence of a cocatalyst. The results obtained confirm that the post-synthetic modification of porous metal-organic frameworks is an efficient approach for preparing heterogeneous catalysts based on the known homogeneous catalysts.