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本文对一部分部位取代的4-硝基咪唑类化合物已用CNDO/2法进行了计算。MO计算结果指出,这些邻位取代4—硝基咪唑类敏化剂具有二个正电荷中心。一个集中在硝基的氮原子上,另一个集中在5—位取代基的硫原子上,而且硫原子上的正电荷比氮原子上的更多。这些敏化剂的另一个显著特点是三个前沿空轨道能量都低于靶分子胸腺嘧啶的最低空轨道能量。其中二个前沿空轨道主要是5-位取代基团的贡献,其余一个前沿空轨道是由于硝基的取代作用。总之这些敏化剂的异常敏化作用是由于双官能团协同作用的结果,而且5—位取代基团如氨磺酰,磺酸盐等对敏化效应的贡献比硝基更重要。
In this paper, some of the 4-nitroimidazole substituted compounds have been calculated by CNDO / 2 method. The MO calculations show that these ortho-substituted 4-nitroimidazole sensitizers have two positive charge centers. One is centered on the nitro nitrogen atom and the other is on the sulfur atom with the 5-position substituent, and the sulfur atom has more positive charge than the nitrogen atom. Another notable feature of these sensitizers is that the energy of the three frontier empty orbitals is lower than the lowest empty orbital energy of the target molecule thymine. Among them, two frontier empty orbitals are mainly contributed by 5-position substituent group, while the other frontier empty orbitals are due to the substitution of nitro groups. In summary, the abnormal sensitization of these sensitizers is due to the synergistic effect of the bifunctional groups, and the contribution of the 5-position substituent groups such as sulfonamide and sulfonate to the sensitization effect is more important than the nitro group.