Haberhauer Gebhard
Institut für Organische Chemie, Fakultät für Chemie, Universität Duisburg-Essen, Universitätsstraße 7, 45117, Essen, Germany.
Chemistry. 2017 Jul 12;23(39):9288-9296. doi: 10.1002/chem.201700566. Epub 2017 May 4.
TICT (twisted intramolecular charge transfer) compounds are characterized by showing a rotation around a single bond in the excited state: starting from an almost planar geometry in the ground state, a twisted system is formed in the electronic excited state. The previously reported PLICT (planarized intramolecular charge transfer) compounds show inverse behavior: starting from a twisted geometry in the electronic ground state, a planarized system is formed in the excited state by rotation around a single bond. Here, a concept for planarized and twisted intramolecular charge transfer (PLATICT) states is presented which amalgamates both (TICT and PLICT) effects. Due to an intramolecular charge transfer, both a twisting around one single bond and a planarization around another one occurs. In sum, the PLATICT system shows two independent rotations around different axes in the excited state. By means of quantum chemical calculations (TD-cam-B3LYP and CC2) and experimental studies, it is demonstrated that N-aryl-substituted 1-aminoindoles are able to form photoinduced PLATICT states. In the fluorescence spectra of N-aryl-substituted 1-aminoindoles with a methoxycarbonyl or a cyano group as substituent in the aryl ring, very large Stokes shifts (ca. 18 000 cm ; >250 nm) are observed. The two independent rotations in the excited state, the very large Stokes shifts and their easy availability starting from indoline, make them very attractive for use as optical switches and motors in various fields of chemistry.
扭曲分子内电荷转移（TICT）化合物的特征在于在激发态下围绕单键发生旋转：从基态的几乎平面几何结构开始，在电子激发态下形成扭曲体系。先前报道的平面化分子内电荷转移（PLICT）化合物表现出相反的行为：从电子基态的扭曲几何结构开始，通过围绕单键旋转在激发态下形成平面化体系。在此，提出了一种平面化和扭曲分子内电荷转移（PLATICT）态的概念，它融合了两种（TICT和PLICT）效应。由于分子内电荷转移，既发生围绕一个单键的扭曲，也发生围绕另一个单键的平面化。总之，PLATICT体系在激发态下围绕不同轴表现出两个独立的旋转。通过量子化学计算（TD-cam-B3LYP和CC2）和实验研究表明，N-芳基取代的1-氨基吲哚能够形成光诱导的PLATICT态。在芳环中带有甲氧基羰基或氰基作为取代基的N-芳基取代的1-氨基吲哚的荧光光谱中，观察到非常大的斯托克斯位移（约18000 cm⁻¹；>250 nm）。激发态下的两个独立旋转、非常大的斯托克斯位移以及从二氢吲哚出发易于获得这些特性，使得它们在化学的各个领域用作光学开关和分子马达非常具有吸引力。
