Ultrafast excited-state proton transfer from hydroxycoumarin-dipicolinium cyanine dyes

作者：Simkovitch Ron; Kisin Finfer Einat; Shomer Shay; Gepshtein Rinat; Shabat Doron; Huppert Dan^*

来源：Journal of Photochemistry and Photobiology A: Chemistry , 2013, 254: 45-53.

DOI：10.1016/j.jphotochem.2013.01.004

• Excited-state proton transfer
• Photoacid
• Near infrared cyanine dye
• Geminate recombination
• Ultrafast phenomena
• Laser induced processes

The photoprotolytic properties of a recently synthesized photoacid, hydroxycoumarin-dipicolinium salt (HCD) were studied by means of time-resolved emission techniques. We found that HCD is a super-photoacid with pK*(a) < -2 and with an excited-state proton transfer to water with a rate constant of k(PT) = 1.4 x 10(11) s(-1). We also found that HCD undergoes ESPT in a large number of protic solvents. The kinetic isotope effect is about two for water, methanol and ethanol.

• 出版日期2013-2-15