Institut für Physikalische Chemie, Friedrich Schiller Universität Jena, Helmholtzweg 4, 07743 Jena, Germany.
Phys Chem Chem Phys. 2011 Aug 28;13(32):14685-93. doi: 10.1039/c1cp20620f. Epub 2011 Jul 6.
Ab initio surface-hopping dynamics calculations have been performed to simulate the intramolecular excited state hydrogen transfer dynamics of ortho-nitrobenzaldehyde (o-NBA) in the gas phase from the electronic S(1) excited state. Upon UV excitation, the hydrogen is transferred from the aldehyde substituent to the nitro group, generating o-nitrosobenzoic acid through a ketene intermediate. The semiclassical propagations show that the deactivation from the S(1) is ultrafast, in agreement with the experimental measurements, which detect the ketene in less than 400 fs. The trajectories show that the deactivation mechanism involves two different conical intersections. The first one, a planar configuration with the hydrogen partially transferred, is responsible for the branching between the formation of a biradical intermediate and the regeneration of the starting material. The conversion of the biradical to the ketene corresponds to the passage through a second intersection region in which the ketene group is formed.
已进行从头表面跳跃动力学计算，以模拟气相中邻硝基苯甲醛（o-NBA）从电子 S（1）激发态的分子内激发态氢转移动力学。在 UV 激发下，氢从醛取代基转移到硝基，通过烯酮中间体生成邻硝基苯甲酸。半经典传播表明，S（1）的失活是超快的，与实验测量结果一致，实验在不到 400 fs 的时间内检测到烯酮。轨迹表明，失活机制涉及两个不同的锥形交叉点。第一个是具有部分转移氢的平面构型，负责形成双自由基中间体和再生起始材料之间的分支。双自由基向烯酮的转化对应于通过第二个交叉区域的传递，其中形成了烯酮基团。
