运用密度泛函理论对13种化合物进行几何结构全优化和频率计算,并计算了其芳香性指标NICS(Nucleus-Independent Chemical Shifts)值,研究了取代基对芳香性的影响以及芳香性与分子稳定性的关系。结果表明吸电子基团可以增加苯环的芳香性,供电子基团可以减低苯环的芳香性,随着体系稳定性的增加,苯环的芳香性降低。
Geometry optimizations and frequency calculations are carried out for 21 compounds by means of density functional theory (DFT). The Nucleus- Independent Chemical Shifts were calculated at B3LYP/6 -311 + + G( d ,p) level of theory. The substituent effects on the aromaticity and relation between them are also studied. Results show aeceptor substitutions can augment aromaticity, however, the donor substitutions will lower aromaticity. Relation between aromaticity and substituent shows that a marked tendency for a decrease of the ring aromaticity, accompanied by an increase in the respective system stability.