title: Proton-coupled electron transfer from tyrosine: a strong rate dependence on intramolecular proton transfer distance.
abstract: Proton-coupled electron transfer (PCET) was examined in a series of biomimetic, covalently linked Ru(II)(bpy)(3)-tyrosine complexes where the phenolic proton was H-bonded to an internal base (a benzimidazyl or pyridyl group). Photooxidation in laser flash/quench experiments generated the Ru(III) species, which triggered long-range electron transfer from the tyrosine group concerted with short-range proton transfer to the base. The results give an experimental demonstration of the strong dependence of the rate constant and kinetic isotope effect for this intramolecular PCET reaction on the effective proton transfer distance, as reflected by the experimentally determined proton donor-acceptor distance.
authors.affiliation: Department of Photochemistry and Molecular Science, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden.
authors.forename: Ming-Tian
authors.initials: MT
authors.lastname: Zhang
authors.forename: Tania
authors.initials: T
authors.lastname: Irebo
authors.forename: Olof
authors.initials: O
authors.lastname: Johansson
authors.forename: Leif
authors.initials: L
authors.lastname: Hammarström
mesh_terms: D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives* / Q000737:chemistry; D056831:Coordination Complexes; D004579:Electron Transport; D004583:Electrons; D010636:Phenols / Q000737:chemistry; D011522:Protons; D014443:Tyrosine / Q000737:chemistry*; D017975:Ruthenium Compounds
chemical_list: D015082:2,2'-Dipyridyl; D056831:Coordination Complexes; D010636:Phenols; D011522:Protons; D014443:Tyrosine; C547232:tris(2,2-bipyridine)-ruthenium(II); D017975:Ruthenium Compounds