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

Ron Simkovitch, Einat Kisin-Finfer, Shay Shomer, Rinat Gepshtein, Doron Shabat, Dan Huppert*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


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 pKa*<-2 and with an excited-state proton transfer to water with a rate constant of kPT=1.4×1011s-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.

Original languageEnglish
Pages (from-to)45-53
Number of pages9
JournalJournal of Photochemistry and Photobiology A: Chemistry
StatePublished - 15 Feb 2013


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


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