Preparation of CuNi/NH₂-MIL-125(Ti) for the photocatalytic synthesis of 1,4-dihydropyridines and -acetamido ketones

Bimetallic CuNi nanoparticles were successfully grown on the surface of a Ti-based metal-organic framework, NH2-MIL-125, via impregnation and chemical reduction processes. The resulting structure, CuNi/NH2-MIL-125, was thoroughly characterized by various techniques, and its photoactivity was evaluated using diffuse reflectance spectroscopy and photoluminescence. The results revealed that CuNi/NH2-MIL-125 has a narrower energy bandgap than NH2-MIL-125 and the heterojunction between the two components (CuNi and NH2-MIL-125) facilitates the separation of the photogenerated charges by suppressing their recombination. The photocatalytic activity of CuNi/NH2-MIL-125 was studied for the one-pot synthesis of 1,4-dihydropyridines (yield = 85-96%, 30-105 min) without further aromatization to pyridines and photo rearrangement to 2,3-dihydropyrroles under light irradiation. For the first time, photo-driven synthesis of beta-acetamido ketones was developed in the presence of a photocatalyst with product yields of 81-93% within 2.5 h. The photocatalyst was chemically stable and photostable and also easily recyclable/reusable for at least four consecutive processes.