Jump to main content
Jump to site search

Issue 9, 2009
Previous Article Next Article

Ultrafast internal conversion pathway and mechanism in 2-(2′-hydroxyphenyl)benzothiazole: a case study for excited-state intramolecular proton transfer systems

Author affiliations

Abstract

We study the ultrafast electronic relaxation of the proton transfer compound 2-(2′-hydroxyphenyl)benzothiazole (HBT) in a joint approach of femtosecond pumpprobe experiments and dynamics simulations. The measurements show a lifetime of 2.6 ps for the isolated molecule in the gas phase in contrast to ∼100 ps for cyclohexane solution. This unexpected decrease by a factor of 40 for the gas phase is explained by ultrafast internal conversion to the ground state promoted by an inter-ring torsional mode. The quantum chemical calculations based on multireference configuration interaction clearly demonstrate that a S0/S1 conical intersection at a 90° twisted structure exists and is responsible for the ultrafast decay. The reaction path leading from the keto form of HBT to this intersection is practically barrierless on the S1 surface. The on-the-fly dynamics simulations using time-dependent density functional theory show that after electronic excitation to the S1 state and after fast excited-state proton transfer (30–50 fs), HBT reaches the region of the S1/S0 crossing within about 500 fs, which will lead to the observed 2.6 ps deactivation to the ground state. After the internal conversion, HBT branches in two populations, one that rapidly closes the proton transfer cycle and another (trans-keto) that takes ∼100 ps for that step.

Graphical abstract: Ultrafast internal conversion pathway and mechanism in 2-(2′-hydroxyphenyl)benzothiazole: a case study for excited-state intramolecular proton transfer systems

Back to tab navigation

Publication details

The article was received on 15 Aug 2008, accepted on 26 Nov 2008 and first published on 13 Jan 2009


Article type: Paper
DOI: 10.1039/B814255F
Citation: Phys. Chem. Chem. Phys., 2009,11, 1406-1415
  •   Request permissions

    Ultrafast internal conversion pathway and mechanism in 2-(2′-hydroxyphenyl)benzothiazole: a case study for excited-state intramolecular proton transfer systems

    M. Barbatti, A. J. A. Aquino, H. Lischka, C. Schriever, S. Lochbrunner and E. Riedle, Phys. Chem. Chem. Phys., 2009, 11, 1406
    DOI: 10.1039/B814255F

Search articles by author

Spotlight

Advertisements