Roy Bonasree, Titov Evgenii, Saalfrank Peter
University of Potsdam, Institute of Chemistry, Theoretical Chemistry, Karl-Liebknecht-Straße 24-25, 14476, Potsdam, Germany.
Chemphyschem. 2024 Nov 4;25(21):e202400331. doi: 10.1002/cphc.202400331. Epub 2024 Sep 29.
Cations of diamondoids and derivatives thereof have recently become the subject of experimental, spectroscopic studies due to their potential role in astrochemistry. In particular, their electronic spectra and photoinduced dynamics trigger great interest. Here, we report on computational investigations of two nitrogen-containing derivatives of the adamantane cation (Ada, ), the amantadine cation (Ama, ) and the 1-cyanoadamantane cation (Ada-CN, CHCN). Specifically, we study electronic (vibrationally resolved) spectra and nonadiabatic molecular dynamics (modeled using the surface hopping approach based on semiempirical electronic structure theory) of these radical cations. The internal conversion time constants as well as reactive relaxation outcomes (cage-opening and hydrogen loss) are compared for the two derivatives and also with the case of Ada. Remarkably, we find a longer ground-state recovery time for Ada-CN than for Ama (for the same excitation energy window), despite a smaller excitation energy for the former. Thus, a static energy gap law cannot be used to rationalize nonadiabatic dynamics and excited state lifetimes in this case: Dynamics and details of the couplings between several states play a decisive role.
由于类金刚石及其衍生物的阳离子在天体化学中可能发挥的作用，它们最近已成为实验光谱研究的对象。特别是，它们的电子光谱和光致动力学引发了极大的兴趣。在此，我们报告对金刚烷阳离子（Ada， ）的两种含氮衍生物、金刚烷胺阳离子（Ama， ）和1-氰基金刚烷阳离子（Ada-CN，CHCN）的计算研究。具体而言，我们研究了这些自由基阳离子的电子（振动分辨）光谱和非绝热分子动力学（使用基于半经验电子结构理论的表面跳跃方法进行建模）。比较了这两种衍生物以及Ada的内转换时间常数和反应性弛豫结果（笼开和氢损失）。值得注意的是，我们发现Ada-CN的基态恢复时间比Ama长（在相同的激发能窗口下），尽管前者的激发能较小。因此，在这种情况下，不能用静态能隙定律来解释非绝热动力学和激发态寿命：几个状态之间耦合的动力学和细节起着决定性作用。
