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Optical and Structural Properties of ESIPT Inspired HBT–Fluorene Molecular Aggregates and Liquid Crystals
The Journal of Physical Chemistry B ( IF 2.8 ) Pub Date : 2017-11-08 00:00:00 , DOI: 10.1021/acs.jpcb.7b08073
Vikas S. Padalkar 1 , Yusuke Tsutsui 1 , Tsuneaki Sakurai 1 , Daisuke Sakamaki 1 , Norimitsu Tohnai 2 , Kenichi Kato 3 , Masaki Takata 3 , Tomoyuki Akutagawa 4 , Ken-ichi Sakai 5 , Shu Seki 1
Affiliation  

In bulk materials, positional isomers not only help in understanding how slight difference in molecular structure alters the crystal packing and optical properties, but also play a key role in developing new type of materials for functional applications. A detailed study on the photophysical properties of fluorene–HBT positional isomers in solution and in the solid state providing a molecular level understanding of the factors which influence fluorescence behavior is reported. Two molecules Ia and IIa were synthesized by Suzuki coupling reaction and their photophysical properties were compared to positional isomers Ib and IIb. Crystal structure analyses and density functional theory (DFT) computation studies were performed to understand structure–properties relation and the results reveal that changing substitution pattern has a marked influence on their packing modes and luminescence properties. Strong noncovalent interactions (π–π) in the solid state hamper the excited state intramolecular proton transfer (ESIPT) process which causes fluorescence quenching in the solid state (Ia and IIa = Φf, 28–40%; Ib and IIb = Φf, 55–67%). Compounds show solvent–responsive and aggregation induced emission (AIE) properties. Bent structures of Ia with double and symmetric substitution of ESIPT motifs exhibit particularly unique condensed phase upon heating, confirmed as a nematic liquid crystalline phase, and this is the first report on the ESIPT and AIE active liquid crystalline materials with a banana-shaped molecule.

中文翻译:

受ESIPT启发的HBT-氟分子聚集体和液晶的光学和结构性质

在散装材料中,位置异构体不仅有助于理解分子结构的微小差异如何改变晶体堆积和光学性质,而且在开发用于功能性应用的新型材料中也起着关键作用。报告了对溶液中和固态中芴-HBT位置异构体的光物理性质的详细研究,从分子水平上了解了影响荧光行为的因素。通过铃木偶联反应合成了两个分子IaIIa,并将它们的光物理性质与位置异构体IbIIb进行了比较。进行了晶体结构分析和密度泛函理论(DFT)计算研究,以了解其结构与性质之间的关系,结果表明,变化的取代模式对其填充模式和发光性能具有显着影响。在固态强非共价相互作用(π-π)阻碍激发态分子内质子转移(ESIPT)方法,该方法导致在固态荧光淬灭(IAIIA˚F,28-40%;IIB˚F,55–67%)。化合物显示出溶剂响应和聚集诱导发射(AIE)特性。Ia的弯曲结构 具有双对称取代的ESIPT母题在加热时表现出特别独特的凝聚相,被确认为向列型液晶相,这是关于ESIPT和AIE具有香蕉形分子的活性液晶材料的首次报道。
更新日期:2017-11-08
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