Urea-pyridine bridged periodic mesoporous organosilica: An efficient hydrogen-bond donating heterogeneous organocatalyst for Henry reaction

Hydrogen-bond donating (HBD) organocatalysts have been employed as an important class of catalysts for the activation of small molecules. However, the use of these catalysts was restricted on account of the self-aggregation of HBD-active species. In this work, a successful approach was developed to construct novel urea pyridine bridged periodic mesoporous organosilica (PMO) to prevent the unwanted self-recognition and aggregation of urea-based catalytic center by spatial isolation, unleashing its HBD organocatalytic activity along with cooperative effect from the pyridine unit for efficient Henry reaction. The urea pyridine bridged PMO catalyst presents high structural stability and high catalytic recyclability. (C) 2015 Elsevier Inc. All rights reserved.