Feuerstein Wolfram, Höfener Sebastian, Klopper Wim, Lamparth Iris, Moszner Norbert, Barner-Kowollik Christopher, Unterreiner Andreas-N
Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), P.O. Box 6980, 76049, Karlsruhe, Germany.
Ivoclar Vivadent AG, Bendererstr. 2, 9494, Schaan, Liechtenstein.
Chemphyschem. 2016 Nov 4;17(21):3460-3469. doi: 10.1002/cphc.201600712. Epub 2016 Sep 16.
In the present study, a selection of basic substitution patterns on benzoyl(trimethyl)germane was investigated using time-dependent density-functional theory (TDDFT) to explore the influence on the stability and on the relative order of the lowest excited electronic states. The theoretical results are in agreement with absorption and fluorescence measurements. We show that electron-withdrawing groups decrease the energetic level of the lowest singlet and triplet state relative to the electron-pushing systems resulting in red-shifted radiative transitions (fluorescence). In the first triplet state electron-withdrawing groups lead to an increased dissociation barrier and a close approach with the singlet ground state before the transition state in the triplet state is reached, favoring radiationless ground-state recovery. The results are also in good agreement with empirical concepts of organic chemistry, therefore providing simple rules for synthetic strategies towards tuning the excited-state properties of benzoylgermanes.
在本研究中，使用含时密度泛函理论（TDDFT）研究了苯甲酰基（三甲基）锗烷上一系列基本取代模式，以探究其对稳定性以及最低激发电子态相对顺序的影响。理论结果与吸收和荧光测量结果一致。我们表明，相对于推电子体系，吸电子基团会降低最低单重态和三重态的能级，导致辐射跃迁（荧光）发生红移。在第一三重态中，吸电子基团会导致解离势垒增加，并且在达到三重态的过渡态之前，会与单重基态紧密靠近，有利于无辐射基态恢复。这些结果也与有机化学的经验概念高度吻合，因此为调整苯甲酰锗激发态性质的合成策略提供了简单规则。
