AM1/CI, CNDO/S and ZINDO/S computations of absorption bands and their intensities in the UV spectra of some 4(3H)-quinazolinones

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2006-10, Vol.65 (2), p.299-307
• Main Authors: Eshimbetov, A.G., Kristallovich, E.L., Abdullaev, N.D., Tulyaganov, T.S., Shakhidoyatov, Kh.M.
• Format: Article
• Language: English
• Subjects: 4(3H)-Quinazolinones; Algorithms; Ethanol; Quinazolinones - analysis; Quinazolinones - chemistry; Semiempirical calculations; Solvents; Spectrophotometry, Ultraviolet; UV spectra
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2005.10.046

A detailed analysis of both frontier MOs and electronic transitions in UV spectra of 16 4-quinazolinone derivatives has been carried out in MO terms, by semiempirical methods AM1/CI, CNDO/S and ZINDO/S. On the basis of experimental and theoretical investigations by the ZINDO/S and CNDO/S methods the long-wavelength bands of 4(3H)-quinazolinone and its derivatives have been assigned to n → π * transition of the C O fragment and to the transition caused by intramolecular charge transfer from Ph and N C N fragments to C O group. It was shown that theoretically obtained electronic transitions applying method AM1/CI are not in agreement with experimental data observed for the 4(3H)-quinazolinone and 2,4(1H,3H)-quinazolinedione. Good correlation of theoretical and experimental data has been obtained by the method ZINDO/S for the wavelengths and the molar extinction coefficients of the compounds studied. Satisfactory correlation of theoretical and experimental data has also been obtained by the method CNDO/S with singly and doubly excited configurations, for the wavelengths only. Such correlations on experimental and theoretical wavelength and molar absorption coefficients of 4-quinazolinone derivatives are carried out for the first time.