Studies of the Optical and Sensing Properties of 1,3,5-Triazine-Cored Star-Shaped (D-π)<sub>3</sub>-A Molecules with Various Amino-Donor-Type Cation Receptors
作者:Hiroki Muraoka、Hikaru Sasaki、Satoshi Ogawa
DOI:10.1246/bcsj.20180355
日期:2019.4.15
We newly designed and synthesized two kinds of 1,3,5-triazine-cored star-shaped (D-π)3-A molecules with 1-aza 15-crown 5-ether receptors (TSM-ACE) and dipicolylamino receptors (TSM-DPA), which possess an intramolecular charge transfer (ICT) nature and exhibit ICT-based optical properties (ICT transition absorption and fluorescence from a ICT excited state). Both TSM-ACE and TSM-DPA display proton-induced optical spectral blue-shifts followed by red-shifts depending on their inherent two-step protonation behavior. Furthermore, TSM-ACE displays optical spectral blue-shifts followed by red-shifts upon stepwise complexation of Mg2+, whereas TSM-DPA displays optical spectral blue-shifts upon the complexation of Zn2+. The cation sensing mechanism can be explained as follows: (i) the initial blue shift is caused by the decreased ICT donor abilities of three amino-donor-type receptors (a decrease of the ICT efficiency) upon binding cations, and (ii) the second red shift is caused by an increased acceptor ability of the 1,3,5-triazine core upon binding cations. Consequently, we revealed that TSM-ACE and TSM-DPA with different cation-recognition functionalities serve as a unique optical sensor capable of visual and distinct detection of not only protons but also different kinds of metal ions.
我们新设计并合成了两种具有1-氮杂15冠5-醚受体(TSM-ACE)和二吡啶氨基受体(TSM)的1,3,5-三嗪核星形(D-π)3-A分子-DPA),具有分子内电荷转移(ICT)性质,并表现出基于 ICT 的光学特性(ICT 跃迁吸收和来自 ICT 激发态的荧光)。 TSM-ACE 和 TSM-DPA 均显示质子引起的光谱蓝移,然后根据其固有的两步质子化行为发生红移。此外,TSM-ACE 在逐步络合 Mg2+ 时显示光谱蓝移,然后显示红移,而 TSM-DPA 在络合 Zn2+ 时显示光谱蓝移。阳离子传感机制可以解释如下:(i)初始蓝移是由三种氨基供体型受体结合阳离子时ICT供体能力降低(ICT效率降低)引起的,以及(ii)第二个红移是由 1,3,5-三嗪核心结合阳离子时受体能力增强引起的。因此,我们发现具有不同阳离子识别功能的 TSM-ACE 和 TSM-DPA 作为独特的光学传感器,不仅能够视觉和清晰地检测质子,还能够检测不同种类的金属离子。