The mechanism of proton transfer between adjacent sites exposed to water

The mechanism of proton transfer between sites that are only a few angstroms apart, using as a model the proton exchange between sites on a small molecule, fluorescein, having two, spectrally distinguishable, proton-binding sites, was investigated. The dynamics of the proton transfer between the two proton-binding sites of the fluorescein indicated that the efficiency of the sites-to-site proton transfer is very sensitive to the presence of the screening electrolyte and has a very high kinetic isotope effect. The state of protonation at each site was constructed. The proton transfer between nearby sites, which were located on a rigid scaffolding, eploys a pathway that utilizes the ordered water in the first solvation layer as carrier.