Department of Physics, Environmental Science and Engineering College, Dalian Maritime University, Dalian 116026, China.
J Comput Chem. 2010 Jul 30;31(10):2056-62. doi: 10.1002/jcc.21492.
In this work, the time-dependent density functional theory (TDDFT) method was carried out to investigate the hydrogen-bonded intramolecular charge-transfer excited state of 2-(4'-N,N-dimethylaminophenyl)imidazo[4,5-b]pyridine (DMAPIP) in methanol (MeOH) solvent. All the geometric conformations of the ground state and locally excited (LE) state and the twisted intramolecular charge-transfer (TICT) state for isolated DMAPIP and its hydrogen-bonded complexes have been optimized. At the same time, the absorption and fluorescence spectra of DMAPIP and the hydrogen-bonded complexes in different electronic states are also calculated. We theoretically demonstrated for the first time that the intermolecular hydrogen bond formed between DMAPIP and MeOH can induce the formation of the TICT state for DMAPIP in MeOH solvent. Therefore, the two components at 414 and 506 nm observed in the fluorescence spectra of DMAPIP in MeOH solvent were reassigned in this work. The fluorescence peak at 414 nm is confirmed to be the LE state. Furthermore, the red-shifted shoulder at 506 nm should be originated from the hydrogen-bonded TICT excited state.
在这项工作中，我们采用含时密度泛函理论（TDDFT）方法研究了 2-（4'-N,N-二甲基氨基苯基）咪唑并[4,5-b]吡啶（DMAPIP）在甲醇（MeOH）溶剂中氢键合的分子内电荷转移激发态。我们优化了孤立 DMAPIP 及其氢键复合物的基态和局域激发（LE）态以及扭曲分子内电荷转移（TICT）态的所有几何构象。同时，我们还计算了 DMAPIP 及其氢键复合物在不同电子态下的吸收和荧光光谱。我们首次从理论上证明了 DMAPIP 与 MeOH 之间形成的分子间氢键可以诱导 DMAPIP 在 MeOH 溶剂中形成 TICT 态。因此，我们重新分配了在 MeOH 溶剂中 DMAPIP 荧光光谱中观察到的两个位于 414nm 和 506nm 的组件。荧光峰 414nm 被确认为 LE 态。此外，506nm 处的红移肩峰应该源自氢键 TICT 激发态。
