Thiourea-functionalized MIL-101(Cr) metal-organic framework as a hydrogen-bond-donating heterogeneous organocatalyst for the Friedel-Crafts alkylation and Biginelli reactions

In the present paper, a functionally diverse thiourea-grafted MOF was fabricated via postsynthetic modification process through complexation of MIL-101(Cr) with pyridine containing thiourea ligand. This new modified material overcomes a significant tendency of hydrogen-bond-donating (HBD) organocatalysts to undergo self-aggregation and subsequent decrease in their solubility and reactivity. A double Lewis acid-HBD catalysis activation mechanism causes the synergistic effect and to some extent has a better performance than the thiourea ligands and the parent MOF in Friedel-Crafts alkylation and Biginelli reactions.