Dynamics of excited-state intramolecular proton-transfer in 2-amino-3-(2′-benzazolyl)quinoline cations. Issue 7 (5th June 2017)

• Record Type: Journal Article
• Authors: Khimich, Mikhail N.; Ivanov, Vladimir L.; Melnikov, Mikhail Ya.; Shelaev, Ivan V.; Gostev, Fedor E.; Nadtochenko, Victor A.; Uzhinov, Boris M.
• Is Part Of: Photochemical & photobiological sciences. Volume 16:Issue 7(2017)
• Page Start: 1139
• Page End: 1145
• Publication Date: 2017-06-05
• Subjects: Photochemistry -- Periodicals; Photobiology -- Periodicals; 541.35
• DOI: 10.1039/c7pp00104e
• Languages: English
• ISSNs: 1474-905X

Abstract

Abstract : Using femtosecond absorption spectroscopy and nanosecond fluorescence spectroscopy, the effective ESIPT time in the cations was determined, which increased with decreasing temperature. Abstract : It was found that cations formed by the protonation of 2-amino-3-(2′-benzoxazolyl)-quinoline (ABO) and 2-amino-3-(2′-benzothiazolyl)-quinoline (ABT) at the nitrogen atom of the quinoline ring exhibit excited-state intramolecular proton transfer (ESIPT). The two-band fluorescence of these cations is due to the emission from two species: the initial tautomer (short-wavelength band) and the ESIPT product (long-wavelength band). The relative intensity of the long-wavelength band depends on the basicity of the proton-accepting moiety and temperature. Quantum-chemical calculations demonstrated that ESIPT in cations involves overcoming a significant potential barrier, which increases with the decreasing basicity of the proton-accepting benzazole moiety. Using femtosecond absorption spectroscopy and nanosecond fluorescence spectroscopy, the effective ESIPT time in the studied cations was determined, which increased with decreasing temperature.