Shanxi Key Laboratory of Macromolecular Science and Technology, Xi'an Key Laboratory of Hybrid Luminescent Materials and Photonic Device, MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions, School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Xi'an, 710072, P. R. China.
Chemistry. 2023 May 11;29(27):e202300320. doi: 10.1002/chem.202300320. Epub 2023 Mar 23.
Most organic thermochromic fluorescent materials exhibit thermo-induced hypsochromic emission due to the formation of excimers in ordered molecular solids; however, it is still a challenge to endow them with bathochromic emission despite its significance in making up the field of thermochromism. Here, a thermo-induced bathochromic emission in columnar discotic liquid crystals is reported realized by intramolecular planarization of the mesogenic fluorophores. A three-armed discotic molecule of dialkylamino-tricyanotristyrylbenzene was synthesized, which preferred to twist out of the core plane to accommodate ordered molecular stacking in hexagonal columnar mesophases, giving rise to bright green monomer emission. However, intramolecular planarization of the mesogenic fluorophores occurred in isotropic liquid increasing the conjugation length, and as a result led to thermo-induced bathochromic emission from green to yellow light. This work reports a new concept in the thermochromic field and provides a novel strategy to achieve fluorescence tuning from intramolecular actions.
大多数有机热致变色荧光材料由于有序分子固体中激基复合物的形成而表现出热致蓝移发射；然而，尽管在热致变色领域中具有重要意义，但赋予其红移发射仍然是一个挑战。在这里，报道了通过介晶荧光团的分子内平面化实现柱状盘状液晶中的热致红移发射。合成了一种三臂盘状分子二烷氨基三氰基三苯乙烯基苯，它倾向于从核心平面扭曲以适应六方柱状介相中的有序分子堆积，从而产生明亮的绿色单体发射。然而，介晶荧光团的分子内平面化发生在各向同性液体中，增加了共轭长度，结果导致热致红移发射从绿光变为黄光。这项工作在热致变色领域报告了一个新概念，并提供了一种通过分子内作用实现荧光调谐的新策略。
