论文部分内容阅读
用含时密度泛函理论(TDDFT)对PP(5-phenyl-5H-phenanthridin-6-one)分子进行了量子化学计算.实验观察到该分子具有双荧光和分子内电荷转移(ICT)特征.理论计算采用B3LYP泛函和6-311+G(2d,p)基组,并用可极化连续介质模型(PCM)处理溶剂效应.基态结构优化表明PP分子为非平面状,苯环和菲啶酮平面的二面角近似等于90.0°.气相和溶剂中低激发态的计算结果表明这些激发态均为局域激发(LE).通过构建气相和溶液中LE→ICT反应和荧光发射的势能曲线,得到了ICT反应的焓变H、能垒Ea以及由于结构弛豫所产生的能量差δEFC.势能曲线的分析和发射能的计算显示PP是一个双荧光体系,包含一个LE发射谱和一个红移的ICT谱.考虑了溶剂效应的计算结果表明,双荧光的产生是由于在ICT反应过程中分子构型的变化,即苯环和菲啶酮单元由相互垂直变成了共平面.
Quantum chemistry calculation of PP (5-phenyl-5H-phenanthridin-6-one) molecule is carried out by time-dependent density functional theory (TDDFT) .It has been observed that this molecule has double fluorescence and intramolecular charge transfer (ICT) The B3LYP functional and 6-311 + G (2d, p) basis sets are used in the theoretical calculations, and the solvent effect is treated by a polarizable continuum model (PCM) .The optimization of the ground state structure indicates that the PP molecules are non-planar and the benzene ring and phenanthridine The dihedral angle of the ketone plane is approximately equal to 90.0 °. The calculation results of the low-excited states in the gas phase and the solvent show that these excited states are localized excitation (LE). By constructing the potential energy curve of LE → ICT reaction and fluorescence emission in gas phase and in solution , The enthalpy change H, energy barrier Ea and energy difference δEFC due to structural relaxation were obtained for ICT reaction.The analysis of potential energy curve and the calculation of the emission energy show that PP is a double fluorescence system and contains one LE emission spectrum and one red The calculation of the solvent effect shows that the double fluorescence is due to the change of the molecular configuration during the ICT reaction, that is, the benzene ring and the phenanthridinone unit become vertically coplanar from each other.