3-吡咯烷基苯并蒽酮的电子结构和光谱性质

苯并蒽酮衍生物在新型荧光材料、非线性光学材料和液晶显示材料等领域有较大的应用前景.本文采用量子化学方法优化了3-吡咯烷基苯并蒽酮的基态几何结构和第一单重激发态的几何结构,并与X射线晶体衍射实验值进行了对比.利用含时密度泛函理论(TD-DFT)的不同泛函,计算了3-吡咯烷基苯并蒽酮在气相和溶剂中的吸收和发射光谱,考察了它的电子结构和光谱特征,并分析了不同泛函、基组以及溶剂效应对吸收和发射光谱的影响.计算结果表明:3-吡咯烷基苯并蒽酮的最强吸收和发射光谱都是具有π→π*跃迁特征的电荷转移(CT)态;泛函B3LYP能较好地重现实验吸收能;而对于具有分子内电荷转移特征的激发态,泛函MPWK能较好地重现实验发射能.溶剂效应的计算表明,不同极性的溶剂对3-吡咯烷基苯并蒽酮的吸收光谱和发射光谱的影响较小.理论预测的光谱与实验结果一致.

Electronic Structures and Spectral Properties of 3-Pyrrolidinobenzanthrone

Benzanthrone derivatives show great potential for use as new luminescent, nonlinear optical, and liquid crystalline materials. The geometries of the ground and the first excited states of 3-pyrrolidinobenzanthrone were optimized using quantum chemistry methods and the obtained structural parameters were compared with experimental data. The time-dependent density functional theory (TD-DFT) calculations were performed to estimate the absorption and emission spectra of 3-pyrrolidinobenzanthrone both in gas-phase and in solutions. In addition, the effects of different exchange correlation functionals, basis sets, and solvents on the absorption and emission spectra were analyzed in detail. We found that the strongest absorption and emission bands of 3-pyrrolidinobenzanthrone could be assigned to a charge transfer (CT) state with a π→π^*character. The result of the B3LYP functional reproduces the experimental absorption spectrum very well and the MPWK functional accurately predicts the emission energy of the first excited state with an intramolecular charge transfer (ICT) feature. The calculated results indicate that solvent effects do not greatly influence the absorption and emission spectra. The theoretical results are in agreement with experimental observations.