Copper-dioxygen complexes and their roles in biomimetic oxidation reactions - Advances in Catalytic Activation of Dioxygen by Metal Complexes - page 79

Chapter 2

Copper-dioxygen complexes and their roles in
biomimetic oxidation reactions

Christiana Xin Zhang, Hong-Chang Liang, Kristi J. Humphreys
and Kenneth D. Karlin
Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA

Abstract Copper-dioxygen interactions are essential from both industrial and biological
perspectives. This review will focus on recent advances in copper-dioxygen complexes with
regard to their relevance to bioinorganic chemistry. New, room-temperature stable copper-
peroxo compounds serve as models for the dioxygen transporting protein hemocyanin. Other
copper-dioxygen complexes with formally-cleaved O-O bonds are also of interest as models
for dioxygen activation. Interest in copper-dioxygen complexes which can oxidize organic
compounds stems from their roles in biological substrate oxidation chemistry as well from
their industrial utility. Copper-dioxygen complexes capable of hydroxylating arenes are
reported which model tyrosinase, an enzyme which catalyzes the ortho -oxygenation of
phenols. Synthetic copper compounds that catalyze the hydroxylation of aliphatic C-H bonds
serve not only as models for industrial processes involving copper catalysts but also as
mimics for copper monooxygenases such as dopamine peptidylglycine
monooxygenase, and particulate methane monooxygenase. Copper-dioxygen
compounds which oxidize benzylic C-H bonds as well as non-activated C-H bonds are
reported, including recent studies where stereoselective hydroxylation occurs. Catechol

oxidase models that catalyze the oxidation of -quinones

are also reported. Other copper oxidase models include mononuclear copper complexes
which catalyze the two-electron oxidation of alcohols to aldehydes, coupled with the
reduction of to through a Cu(II) phenoxyl-radical species, closely mimicking the
mechanism of galactose oxidase. A dinuclear copper complex is reported which also
catalyzes the aerobic oxidation of alcohols to the corresponding aldehydes and ketones.

o -diphenols to their corresponding o

DNA

as a substrate for oxidation by copper-phenanthroline compounds is overviewed.

Key Words : bioinorganic chemistry, model compounds, dioxygen activation,
binuclear copper, catalytic oxidation, alcohol and DNA oxidation

1. INTRODUCTION

In this review, we provide a bioinorganic perspective in overviewing
recent advances in the chemistry of copper-dioxygen [dioxygen; molecular