TD-DFT calculations of absorption bands and their intensities in the UV spectra of some tetrahydroquinolines

COOKE, M. V.; MALVACIO, I.; PELÁEZ, W. J.; PEPINO, A. J.; MAZZIERI, M. R.; ARGÜELLO, G.A.

RSC Advances

Royal Society Chemistry

Lugar: CAMBRIDGE; Año: 2015 p. 26255 - 26262

2046-2069

TD-DFT calculations of UV absorption bands and their intensities in the spectra of some tetrahydroquinolines. María V. Cooke,a Ivana Malvacio,a Walter J. Peláez, a,* Ana J. Pepino,a María R. Mazzieri,b and Gustavo A. Argüelloa a INFIQC-Dpto. de Fisicoquímica, Facultad de Ciencias Químicas, UNC, Córdoba, 5000, Argentina.b Dpto. de Farmacía, Facultad de Ciencias Químicas, UNC, Córdoba, 5000, Argentina. E-mail: waldemar31@fcq.unc.edu.ar Abstract A detailed analysis of the MOs involved in electronic transitions in UV spectra as well as a conformational study of 1-benzenesulfonyl-1,2,3,4-tetrahydroquinoline (BSTHQs) derivatives has been carried out using the TD-DFT (B3LYP/6-31+G(d,p)) method. Based on experimental solvent effects and theoretical investigations the long-wavelength bands have been assigned to π → π* transitions caused by HOMO-LUMO intramolecular charge transfer from the tetrahydroquinoline fragment (THQ) to the benzenesulfonyl moiety (BS). Nevertheless, for the NO2 derivative the HOMO-LUMO transition was found to be forbidden. In this case the long-wavelength band has been associated to an n → π* transition. Good correlation of theoretical and experimental data for the energy transitions and the molar extinction coefficients of the compounds studied has been obtained and are presented for the first time.