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.