Role of Proton-Coupled Electron Transfer in O–O Bond Activation

Joel Rosenthal received a B.S. degree with honors in chemistry and mathematics from New York University in 2001. As an undergraduate, Joel carried out research with Professor David I. Schuster on the photochemical addition of enones to fullerenes. As a Fannie and John May Hertz Foundation Fellow at the Massachusetts Institute of Technology (MIT), he pursued graduate studies with Nocera centered on the study of proton-coupled electron transfer in model donor–acceptor systems and the design of discrete catalysts for water–oxygen interconversion. Following the completion of his Ph.D. studies, Joel has assumed a position in the laboratory of Professor Stephen J. Lippard at MIT as a NIH postdoctoral fellow to design sensors for in vivo metalloneurochemistry studies.

Daniel G. Nocera is the W. M. Keck Professor of Energy and Professor of Chemistry in the Department of Chemistry at The Massachusetts Institute of Technology. He received his undergraduate degree from Rutgers University in 1979. He pursued graduate studies at the California Institute of Technology with Harry B. Gray and received his Ph.D. in 1984. Nocera began his independent research career at Michigan State University and then moved to MIT in 1997. His research interests are focused on biological and chemical energy conversion with a primary focus in recent years on the photogeneration of hydrogen and oxygen from water using light.

The selective reduction of oxygen to water requires four electrons and four protons. The design of catalysts that promote oxygen reduction therefore requires the management of both electron and proton inventories. Pacman and Hangman porphyrins provide a cleft for oxygen binding, a redox shuttle for oxygen reduction, and functionality for tuning the acid–base properties of bound oxygen and its intermediates. With proper control of the proton-coupled electron transfer events, O–O bond breaking of oxygen, and more generally oxygenated substrates, may be achieved with high efficiencies. The rule set developed for oxygen reduction may be applied to a variety of other small molecule activation reactions of consequence to energy conversion.