Probing the dynamics of solvation and structure of the OH- ion in aqueous solution from picosecond transient absorption measurements.
The reaction of intracomplex proton transfer (44BPY(-.)...HO-H) (R)-->44BPYH(.)+ OH(-) that follows the photoreduction of 4,4'-bipyridine (44BPY) into its anion radical 44BPY(-) in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) is investigated in acetonitrile-water mixtures by using picosecond transient absorption. The dependence of the appearance kinetics of the 44BPYH(.) radical on the water content reveals a highly diffusional proton transfer process that is controlled by the dynamics of solvation of the released hydroxide ion. The results are interpreted on the basis of a two-step mechanism where an intermediate solvation complex (44BPYH(.))OH(-)(H(2)O)(3) is formed first before evolving toward a final four-water hydration structure OH(-)(H(2)O)(4).
Poizat
Olivier
O
Laboratoire de Spectrochimie Infrarouge et Raman (UMR 8516 de l'Université et du CNRS), Centre d'Etudes et de Recherches Lasers et Applications (FR 2416 du CNRS), Bât. C5, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq, France. olivier.poizat@univ-lille1.fr
Buntinx
Guy
G
D006878:Hydroxides / Q000737:chemistry*; D007700:Kinetics; D011522:Protons; D011725:Pyridines; D012995:Solubility; D012996:Solutions; D014867:Water / Q000737:chemistry*
D006878:Hydroxides; D011522:Protons; D011725:Pyridines; D012996:Solutions; D014867:Water; C031356:hydroxide ion; C034306:4,4'-bipyridyl