1009317-35-4Relevant academic research and scientific papers
Electron transfer between hydrogen-bonded pyridylphenols and a photoexcited rhenium(I) complex
Herzog, William,Bronner, Catherine,Loeffler, Susanne,He, Bice,Kratzert, Daniel,Stalke, Dietmar,Hauser, Andreas,Wenger, Oliver S.
, p. 1168 - 1176 (2013/06/27)
Two pyridylphenols with intramolecular hydrogen bonds between the phenol and pyridine units have been synthesized, characterized crystallographically, and investigated by cyclic voltammetry and UV/Vis spectroscopy. Reductive quenching of the triplet metal-to-ligand charge-transfer excited state of the [Re(CO)3(phen)(py)]+ complex (phen=1,10-phenanthroline, py=pyridine) by the two pyridylphenols and two reference phenol molecules is investigated by steady-state and time-resolved luminescence spectroscopy, as well as by transient absorption spectroscopy. Stern-Volmer analysis of the luminescence quenching data provides rate constants for the bimolecular excited-state quenching reactions. H/D kinetic isotope effects for the pyridylphenols are on the order of 2.0, and the bimolecular quenching reactions are up to 100 times faster with the pyridylphenols than with the reference phenols. This observation is attributed to the markedly less positive oxidation potentials of the pyridylphenols with respect to the reference phenols (≈0.5 V), which in turn is caused by proton coupling of the phenol oxidation process. Transient absorption spectroscopy provides unambiguous evidence for the photogeneration of phenoxyl radicals, that is, the overall photoreaction is clearly a proton-coupled electron-transfer process. A concerted effort: Two pyridylphenols with intramolecular hydrogen bonds react with a metal complex through concerted proton transfer (PT)-electron transfer (ET). Upon photoexcitation of the complex, ET occurs from the phenol to the metal, and the phenolic proton is transferred to the pyridine moiety (see picture; MLCT=metal-to-ligand charge transfer). Copyright
Concerted proton-electron transfer in pyridylphenols: The importance of the hydrogen bond
Markle, Todd F.,Mayer, James M.
, p. 738 - 740 (2008/12/20)
(Chemical Equation Presented) Slowed down by a break up: One-electron oxidation of intramolecularly hydrogen-bonded phenol-pyridine compounds 1 and 2 involves proton transfer coupled with electron transfer (see scheme; B = base). At the same driving force, 2 reacts substantially slower than 1. The methylene group between the phenol and pyridine groups in 2 breaks the conjugation between the rings, which has a marked effect on the hydrogen bond and is likely the origin of the difference in rate constants.
