Iridium Complex Immobilized on Custom-Designed Periodic Mesoporous Organosilica as Reusable Catalyst for the Dehydrogenative Oxidation of Alcohols

Over the past few decades, a number of homogeneous transition metal complex catalysts for efficient organic transformations have been developed. Some of these highly active catalysts have been designed based on the concept of "cooperativity between a transition metal atom and a custom-designed ligand molecule". In this paper, we report the synthesis of a periodic mesoporous organosilica (PMO) catalyst support (BPyOH-BP-PMO) that enables cooperativity between a transition-metal atom and the custom-designed ligand. We immobilized iridium complexes on BPyOH-BP-PMO to produce a heterogeneous catalyst that exhibits excellent catalytic activity for the dehydrogenative oxidation of a variety of alcohols and is superior to a similar previously used homogeneous catalyst. Furthermore, the immobilized catalyst (Ir@BPyOH-BP-PMO) can be recovered by simple filtration and reused without decrease of its catalytic activity. We believe that the concept for the design of the present heterogeneous catalyst would provide important guidance for the development of innovative catalysts.