Cooperative Activation of O2 by Heteronuclear Assemblies

Dioxgyen (O₂) activation and reduction are not only vital for aerobic life, but also essential to industrial applications such as sustainable fuel cells. Dioxgyen is clean, abundant, and a powerful four-electron oxidant, but also kinetically inert and requires activation. In Nature, the activation of O₂ is often facilitated by transition metal centers at metalloenzyme active sites. For example, during the cellular respiration reaction, mitochondrial Cytochrome c Oxidase (CcO) utilizes a unique heme-copper binuclear active site to carry out the enzymatic four-electron four-proton reduction of O₂ to water. This reaction is coupled with the process of proton pumping and the biological ATP production. While the mechanistic investigations of CcO over a period of five decades have led to significant insight into the cooperative O₂ chemistry at the iron/copper sites, the vital aspects of the oxidized/resting state of CcO for its enzymatic function is yet to be understood. Moreover, the examples of such cooperative O₂ chemistry at heterobinuclear centers are only limited to heme/copper assemblies. Our research goal is to contribute to a fundamental understanding of the delicate cooperativity of the two different metal centers in O₂ chemistry. This seminar will focus on our recent studies looking into how the cooperativity triggers formation of new intermediates and reactivities.