Solvent-Free Preparation of Pharmaceutically Active Diindolylmethane Derivatives by Stable Triple-Interpenetrated...

The construction of noble metal-coordinated heterometallic-organic framework (HMOF) catalysts is crucial for advancing sustainable and efficient organic synthesis, particularly in drug synthesis. However, the controlled assembly of these materials is hindered by the inherently slow ligand exchange kinetics of noble metal ions and the challenging balance between the strength and reversibility of coordination bonds. Herein, a series of stable HMOFs (ScPd-INA, ScPt-INA, and ScPt-MCA) were one-pot synthesized by the bifunctional 4-picolinic acid (HINA)/3-methylpyridine-4-carboxylic acid (HMCA), featuring the triple-interpenetrated structures and unique [Sc₃(µ₃-O)(COO)₆] clusters. As heterogeneous catalysts, these HMOFs exhibit exceptional efficiency (up to 99%) and stability in the solvent-free Friedel-Crafts alkylation of pharmacologically significant diindolylmethane derivatives. Notably, four products were successfully identified by the single-crystal X-ray diffraction, one of which was the drug molecule 3,3'-[(4-methoxyphenyl)methylene]bis-1H-indole (DIM-C-pPhOCH₃), marking the first reported structural analysis of DIM-C-pPhOCH₃ by the MOF catalytic system. Moreover, the theoretical calculations further clarified the synergistic interplay between the dual metal centers in promoting the reaction. This work establishes an efficient approach for constructing noble metal-coordinated HMOF catalysts, offering a new platform for their applications in the synthesis of drug molecules.