ULTRAFAST EXCITED-STATE PROTON-TRANSFER FROM CYANO-SUBSTITUTED 2-NAPHTHOLS

The rate of excited-state proton transfer from four cyano-substituted 2-naphthols was measured in H2O and D2O by picosecond time-resolved fl uorescence. The excited-state acidity constant, pK(a), was calculated and compared with previous results and was found to be substitution-d ependent, as predicted by the charge-transfer theory. The isotope effe ct was evaluated for all the compounds of the series. As reported for many other hydroxyaromatic compounds, this effect was more important f or the dissociation rate constant than for the recombination rate cons tant.