Wang Shiyin, Liu Haichao, Zhao Shuaiqiang, Wu Qiaolin, Yang Zhiqiang, Yang Daojie, Lv Yingbo, Su Qing, Zhang Shi-Tong, Yang Bing
State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University Changchun 130012 China
College of Chemistry, Jilin University Changchun 130012 China.
Chem Sci. 2025 Jan 8;16(7):3275-3284. doi: 10.1039/d4sc08001g. eCollection 2025 Feb 12.
Must excimers quench fluorescence? This study aims to clarify the misconception that excimers are defective species with weak fluorescence. For this purpose, we utilized a rigid xanthene template to connect anthracene units for constructing an inter-excimer and an intra-excimer. Their photophysical properties were systematically investigated in solution and crystal forms, representing dynamic and static environments, respectively. In solutions, the inter- and intra-excimers exhibited low fluorescence efficiencies due to the limited formation and ease of dissociation of the excimers. In crystals, the inter- and intra-excimers both demonstrated a significant increase in fluorescence efficiency, which was ascribed to the greatly suppressed non-radiation for the static excimer in a rigid environment. Furthermore, the efficiency of the inter-excimer was higher than that of the intra-excimer, which arose from the more stable excited state for more effective non-radiative suppression. Therefore, it was concluded that the probability and stability of excimer formation are the key factors for improving excimer fluorescence efficiency. Overall, their fluorescence efficiencies can be ranked as follows: dynamic inter-excimer < dynamic intra-excimer < static intra-excimer < static inter-excimer, which is subjected to environmental rigidity and excimer stability. This work will provide a comprehensive understanding of excimers and propose a novel design strategy to achieve high-efficiency fluorescent materials for innovative organic photo-functional applications.
准分子一定会淬灭荧光吗？本研究旨在澄清准分子是具有弱荧光的缺陷物种这一误解。为此，我们利用刚性呫吨模板连接蒽单元来构建分子间准分子和分子内准分子。分别在溶液和晶体形式中系统地研究了它们的光物理性质，溶液和晶体形式分别代表动态和静态环境。在溶液中，由于准分子形成受限且易于解离，分子间和分子内准分子均表现出低荧光效率。在晶体中，分子间和分子内准分子的荧光效率均显著提高，这归因于刚性环境中静态准分子的非辐射大幅受到抑制。此外，分子间准分子的效率高于分子内准分子，这源于更稳定的激发态以实现更有效的非辐射抑制。因此，得出结论，准分子形成的概率和稳定性是提高准分子荧光效率的关键因素。总体而言，它们的荧光效率可按以下顺序排列：动态分子间准分子＜动态分子内准分子＜静态分子内准分子＜静态分子间准分子，这取决于环境刚性和准分子稳定性。这项工作将为准分子提供全面的理解，并提出一种新颖的设计策略，以实现用于创新有机光功能应用的高效荧光材料。
