Eshimbetov A G, Kristallovich E L, Abdullaev N D, Tulyaganov T S, Shakhidoyatov Kh M
S.Yu. Yunusov Institute of Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent 700170, Uzbekistan.
Spectrochim Acta A Mol Biomol Spectrosc. 2006 Oct;65(2):299-307. doi: 10.1016/j.saa.2005.10.046. Epub 2006 Feb 21.
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-->pi(*) transition of the CO fragment and to the transition caused by intramolecular charge transfer from Ph and NCN fragments to CO 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.
通过半经验方法AM1/CI、CNDO/S和ZINDO/S，从分子轨道角度对16种4-喹唑啉酮衍生物的前沿分子轨道和紫外光谱中的电子跃迁进行了详细分析。基于ZINDO/S和CNDO/S方法的实验和理论研究，4(3H)-喹唑啉酮及其衍生物的长波长带被归因于CO片段的n→π*跃迁以及由分子内电荷从Ph和NCN片段转移至CO基团所引起的跃迁。结果表明，应用AM1/CI方法理论获得的电子跃迁与4(3H)-喹唑啉酮和2,4(1H,3H)-喹唑啉二酮的实验数据不一致。通过ZINDO/S方法，在所研究化合物的波长和摩尔消光系数方面获得了理论与实验数据的良好相关性。通过CNDO/S方法，对于单激发和双激发构型，仅在波长方面也获得了理论与实验数据的满意相关性。4-喹唑啉酮衍生物的实验和理论波长及摩尔吸收系数的这种相关性首次得以实现。
