The electronic structure of a series of benzo[cd]indole-based merocyanines and cationic polymethine dyes has been analyzed in both the ground and fluorescent states using the DFT and TD-DFT computations. The obtained data has shown the marked difference between the benzo[cd]indole dyes and those based on such typical heterocyclic cores as indole and benzimidazole. Namely, in the former, the frontier MOs have much greater coefficients at the end group(s), which leads to an enhancement of vibronic interactions in the long-wavelength absorption and fluorescence transitions. This effect seems to be the major cause of the low fluorescence lifetimes and fluorescence quantum yields of benzo[cd]indole dyes.

使用DFT和TD-DFT计算，已在基态和荧光状态下分析了一系列基于苯并[ cd ]吲哚的花菁和阳离子聚次甲基染料的电子结构。所得数据表明，苯并[ cd ]吲哚染料与基于吲哚和苯并咪唑等典型杂环核的染料之间存在显着差异。即，在前者中，前沿MO在端基上具有更大的系数，这导致长波吸收和荧光跃迁中的电子相互作用增强。该效应似乎是苯并[ cd ]吲哚染料的低荧光寿命和低荧光量子产率的主要原因。