Computational study of electronic-vibrational spectrum of rotamers of 2-(2'-hydroxyphenyl)benzoxazole

Abstract

UV-vis absorption spectrum of internally hydrogen-bonded enol structures of 2-(2'-hydroxyphenyl)benzoxazole is calculated for the transitions to the first excited state using the Franck-Condon approximation and harmonic model for vibrations. It is shown that the absorption spectrum of the structure with the hydrogen bond OH...O is shifted to larger energy by about 0.13 eV compared to the spectrum of the most stable structure with the hydrogen bond OH...N. The largest intensity of vibronic transitions to the first electronic state of the OH...O structure demonstrates high-frequency vibrations involving deformation mode of the oxazole ring, stretching of the both aromatic rings, and stretching of the bond linking the benzoxazole and phenyl moieties.