Song Mengyuan, Liu Meng, Zhang Xue, Qin Haijuan, Sun Jinglu, Wang Juanjuan, Peng Qian, Zhao Zhiwei, Zhao Guohui, Yan Xianchang, Chang Yongxin, Zhang Yahui, Wang Dongdong, Wang Junhui, Zhao Jianzhang, Qing Guangyan
State Key Laboratory of Medical Proteomics, National Chromatographic R. & A. Center, CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian 116023 P. R. China
University of Chinese Academy of Sciences Beijing 100049 P. R. China
Chem Sci. 2025 Apr 22. doi: 10.1039/d4sc08197h.
Excitation wavelength-dependent (Ex-De) chromophores, which exhibit changes in spectral composition with varying excitation wavelengths, have garnered significant interest. However, the pursuit of novel photoluminescence (PL) mechanisms and high luminescence quantum yields is facing huge challenges. Here, we discover that the introduction of a spinacine moiety to 2-(2-hydroxy-5-methylphenyl)benzothiazole, a traditional excited-state intramolecular proton transfer (ESIPT) fluorophore, results in a novel Ex-De PL molecule. The luminescent color of this compound can be effectively modulated from greenish-blue to yellow-green by adjusting either the excitation wavelength or temperature. Transient absorption and spectroelectrochemistry spectra elucidate the underlying mechanism, demonstrating the roles of ESIPT and proton-coupled electron transfer (PCET). When embedded in a poly(vinyl alcohol) film, the composite exhibits remarkable Ex-De PL behavior, achieving absolute fluorescence quantum yields of 55.6% ( : 396 nm) and 69.6% ( : 363 nm), as well as phosphorescence at room temperature. These properties highlight its potential for multiple encryption features, enhancing its application in anti-counterfeiting technologies.
激发波长依赖型（Ex-De）发色团，即随着激发波长变化而呈现光谱组成改变的发色团，已引起了广泛关注。然而，追求新型光致发光（PL）机制和高发光量子产率正面临巨大挑战。在此，我们发现，在传统的激发态分子内质子转移（ESIPT）荧光团2-(2-羟基-5-甲基苯基)苯并噻唑中引入菠菜碱部分，可得到一种新型的Ex-De PL分子。通过调节激发波长或温度，该化合物的发光颜色可从蓝绿色有效调制为黄绿色。瞬态吸收光谱和光谱电化学光谱阐明了其潜在机制，证明了ESIPT和质子耦合电子转移（PCET）的作用。当嵌入聚乙烯醇薄膜中时，该复合材料表现出显著的Ex-De PL行为，绝对荧光量子产率分别达到55.6%（激发波长：396 nm）和69.6%（激发波长：363 nm），并且在室温下还具有磷光。这些特性突出了其具备多种加密特征的潜力，增强了其在防伪技术中的应用。
