Estrada Leandro A, Francés-Monerris Antonio, Schapiro Igor, Olivucci Massimo, Roca-Sanjuán Daniel
Center for Photochemical Sciences, Bowling Green State University, Bowling Green, OH, USA.
Institut de Ciència Molecular, Universitat de València, P.O. Box 22085, ES-46071, Valencia, Spain.
Phys Chem Chem Phys. 2016 Dec 7;18(48):32786-32795. doi: 10.1039/c6cp05231b.
Herein, we report complementary computational and experimental evidence supporting the existence, for indan-1-ylidene malononitrile and fluoren-9-ylidene malononitrile, of a non-radiative decay channel involving double bond isomerisation motion. The results of UV-Vis transient absorption spectroscopy highlight that the decay takes place within hundreds of picoseconds. In order to understand the related molecular mechanism, photochemical reaction paths were computed by employing multiconfigurational quantum chemistry. The results indicate that the excited state deactivation occurs via concerted double bond twisting of the dicyanovinyl (DCV) unit coupled with a pyramidalisation of its substituted carbon. It is also shown that the observed differences in the excited state lifetimes when passing from indan-1-ylidene malononitrile to fluoren-9-ylidene are associated with the change in the topography of the conical intersection driving the decay from intermediate to sloped, respectively.
在此，我们报告了补充性的计算和实验证据，支持茚满-1-亚基丙二腈和芴-9-亚基丙二腈存在涉及双键异构化运动的非辐射衰变通道。紫外可见瞬态吸收光谱的结果表明，衰变发生在数百皮秒内。为了理解相关的分子机制，采用多组态量子化学计算了光化学反应路径。结果表明，激发态失活是通过二氰基乙烯基（DCV）单元的协同双键扭转及其取代碳的锥形化发生的。还表明，从茚满-1-亚基丙二腈到芴-9-亚基时观察到的激发态寿命差异分别与驱动衰变从中间到倾斜的锥形交叉点的地形变化有关。
