The kinetic effect of internal hydrogen bonds on proton-coupled electron transfer from phenols: a theoretical analysis with modeling of experimental data.

摘要: Proton-coupled electron transfer (PCET) was studied in two biomimetic covalently linked Ru(bpy)3−tyrosine complexes with the phenolic proton hydrogen-bonded to an internal carboxylate group. The group is either a salicylic acid (o-hydroxybenzoic acid, SA) or o-hydroxyphenyl-acetic (PA), where former gives resonance-assisted hydrogen bond. Transient absorption data allowed direct determination of rate constant for these intramolecular, bidirectional, and concerted PCET (CEP) reactions, as function temperature H/D isotope. We found, unexpectedly, that bond SA fact weaker than complex PA, which forced us reassess earlier hypothesis coupling term CEP increased by stronger Consequently, kinetic modeled numerically using quantum mechanical expression. Sufficient experimentally determined observables were available give robust well-determined par...