Congratulations to Sanjeevi Jayakumar whose paper on Cationic Zn-Porphyrin Immobilized in Mesoporous Silicas as Bifunctional Catalyst for CO2 Cycloaddition Reaction under Cocatalyst Free Conditions has been published in ACS Sustainable Chemistry & Engineering (DOI: 10.1039/c7gc03801a) and was selected on the cover.
Immobilization of metalloporphyrin onto solid support is highly desirable in chemical industry. Herein, we reported for the first time the efficient immobilization of cationic zincporphyrin complexes on mesoporous SBA-15 by a simple one-pot method by refluxing 5,10,15,20-tetrakis(4-pyridyl)porphyrin zinc (II) (Zn-TPy), SBA-15 and 3-(trimethoxysilyl)propyl bromide in toluene or DMF or NMP or THF. Studies suggest that solid catalyst with high Zn content, stiochiometric Br–/Zn ratio and uniform distribution of active sites could be obtained using DMF as solvent, possibly related with its suitable polarity. The bifunctional solid material with both Lewis acid site and nucleophile acts as an efficient catalyst for catalyzing cycloaddition of CO2 and epoxides under co-catalyst free conditions. Compared with homogeneous counterpart, the solid catalyst is more active (TOF: 1686 h-1 versus 370 h-1). This suggests the closely connected Lewis acid and Br– in solid material could enhance their cooperation during catalytic process. This work provides an efficient method for the synthesis of bifunctional solid catalyst exhibiting enhanced cooperation activation effect for CO2 cycloaddition reaction.