Palladium-anchored multidentate SBA-15/di-urea nanoreactor: A highly active catalyst for Suzuki coupling reaction

Modification of mesoporous silica was carried out by reaction of SBA-15 with di-urea-based ligand. Next, with the help of this ligand, palladium ions were anchored within the multidentate SBA-15/di-urea pore channels with high dispersion. The SBA-15/di-urea/Pd catalyst was characterized using various techniques. Theoretical calculations indicated that each palladium ion was strongly interacted with one nitrogen and two oxygen atoms from the multidentate di-urea ligand located in SBA-15 channels and these interactions remained during the catalytic cycle. These results are in good agreement with those of hot filtration test: the palladium ions have very high stability against leaching from the SBA-15/di-urea support. The catalytic performance of SBA-15/di-urea/Pd nanostructure was examined for the Suzuki coupling reaction of phenylboronic acid and electronically diverse aryl halides under mild conditions with a minimal amount of Pd (0.26mol%). Compared to previous reports, this protocol afforded some advantages such as short reaction times, high yields of products, catalyst stability without leaching, easy catalyst recovery and preservation of catalytic activity for at least six successive runs.