Pizano, Arturo A.Yang, Jay L.Nocera, Daniel2017-07-202012Pizano, Arturo A., Jay L. Yang, and Daniel G. Nocera. 2012. “Photochemical Tyrosine Oxidation with a Hydrogen-Bonded Proton Acceptor by Bidirectional Proton-Coupled Electron Transfer.” Chemical Science 3 (8): 2457. doi:10.1039/c2sc20113e.2041-6520http://nrs.harvard.edu/urn-3:HUL.InstRepos:33468926Amino acid radical generation and transport are fundamentally important to numerous essential biological processes to which small molecule models lend valuable mechanistic insights. Pyridyl-amino acid-methyl esters are appended to a rhenium(I) tricarbonyl 1,10-phenanthroline core to yield rhenium–amino acid complexes with tyrosine ([Re]–Y–OH) and phenylalanine ([Re]–F). The emission from the [Re] center is more significantly quenched for [Re]–Y–OH upon addition of base. Time-resolved studies establish that excited-state quenching occurs by a combination of static and dynamic mechanisms. The degree of quenching depends on the strength of the base, consistent with a proton-coupled electron transfer (PCET) quenching mechanism. Comparative studies of [Re]–Y–OH and [Re]–F enable a detailed mechanistic analysis of a bidirectional PCET process.en-USJournal Article2017-05-1120122017-07-2010.1039/C2SC20113E