Rappoport Dmitrij, Furche Filipp
Institut für Physikalische Chemie, Universität Karlsruhe, Kaiserstrasse 12, 76128 Karlsruhe, Germany.
J Am Chem Soc. 2004 Feb 4;126(4):1277-84. doi: 10.1021/ja037806u.
Recent advances in time-dependent density functional theory (TDDFT) have led to computational methods that can predict properties of photoexcited molecules with satisfactory accuracy at comparably moderate cost. We apply these methods to study the photophysics and photochemistry of 4-(dimethyl)aminobenzonitrile (DMABN). DMABN is considered the paradigm of photoinduced intramolecular charge transfer (ICT), leading to dual fluorescence in polar solvents. By comparison of calculated emission energies, dipole moments, and vibrational frequencies with recent results from transient spectroscopy measurements, a definitive assignment of the electronic and geometric structure of the two lowest singlet excited states of DMABN is possible for the first time. We investigate the mechanism of the ICT reaction by means of minimum energy path calculations. The results confirm existing state-crossing models of dual fluorescence. Our study suggests that analytical TDDFT derivative methods will be useful to predict and classify emissive properties of other donor-acceptor systems as well.
含时密度泛函理论（TDDFT）的最新进展带来了一些计算方法，这些方法能够以相对适中的成本，较为准确地预测光激发分子的性质。我们运用这些方法来研究4-（二甲基）氨基苯甲腈（DMABN）的光物理和光化学性质。DMABN被视为光致分子内电荷转移（ICT）的范例，在极性溶剂中会产生双重荧光。通过将计算得到的发射能量、偶极矩和振动频率与瞬态光谱测量的最新结果进行比较，首次有可能明确确定DMABN两个最低单重激发态的电子和几何结构。我们通过最小能量路径计算来研究ICT反应的机理。结果证实了现有的双重荧光态交叉模型。我们的研究表明，解析TDDFT导数方法对于预测和分类其他供体-受体体系的发射性质也将是有用的。
