氟取代对香豆素分子超快动力学过程的影响  

Impact of Fluorine Substitution on the Ultrafast Dynamic Processes of Coumarin Molecules

作　　者：葛晶 李智彪 薛丙乾 白西林 GE Jing;LI Zhi-biao;XUE Bing-qian;BAI Xi-lin(School of Physics and Information Engineering,Shanxi Normal University,Ta iyuan 030031,China;Key Laboratory of Spectral Measurement and Analysis of Shanxi Province,Taiy uan 030031,China)

机构地区：[1]山西师范大学物理与信息工程学院,山西太原030031 [2]山西省光谱测量与分析重点实验室,山西太原030031

出　　处：《光谱学与光谱分析》2024年第11期3128-3135,共8页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(21903050);山西省基础研究计划项目(20210302124124);山西省回国留学人员科研项目(2021-092);山西省留学人员科技活动择优项目(20220024)资助。

摘　　要：设计具有高亮度、高光稳定性和环境友好型的荧光染料,是当前备受关注的前沿领域。研究发现,荧光染料的发光效率受到扭转分子内电荷转移(TICT)的影响。因此,有效地抑制TICT过程对于荧光标记物和探针的研究与开发具有至关重要的意义。香豆素及其衍生物,尤其是具有高荧光产率和长荧光寿命的7-氨基香豆素染料,一直以来都广泛应用于不同体系中,作为荧光探针的重要组成部分。然而,以往的研究主要集中在探究不同溶剂对香豆素染料分子激发态动力学过程的影响,而忽略了染料分子结构对TICT过程的重要作用。采用了飞秒时间分辨瞬态吸收(TA)光谱和密度泛函理论(DFT)计算相结合的方法,深入研究香豆素染料C460和C481在不同溶剂中的激发态动力学。研究结果揭示,在具有高强供氢能力的高极性甲醇溶剂中,C481才显著发生TICT过程。此外,量子化学计算结果表明,氟取代效应会降低分子内扭转势垒,导致非辐射失活效应加速,从而引发更为明显的荧光猝灭现象。这一研究不仅有助于优化荧光染料性能时选择合适的溶剂,还可为荧光染料分子结构的设计提供重要的指导,具有深远的研究价值。The development of highly efficient,photostable,and eco-friendly fluorescent dyes is currently a prominent focus in scientific research,attracting significant attention.Recent studies have emphasized Twisted Intramolecular Charge Transfer(TICT)'s crucial role in determining fluorescent dyes'luminescence efficiency.Consequently,effectively suppressing the TICT process is imperative for progressing fluorescent markers and probes.Among the various fluorescent dyes,coumarin and its derivatives,particularly 7-amino coumarin dyes,have gained significant recognition as extensively utilized constituents in diverse systems owing to their robust fluorescence and prolonged fluorescence lifetimes.Nevertheless,previous examinations have predominantly concentrated on the effect of different solvents on the excited-state behavior of coumarin dye molecules,overlooking the significant influence of dye molecule structure on the TICT process.This study utilized a combination of femtosecond time-resolved transient absorption(TA)spectroscopy and density functional theory(DFT)calculations to gain deeper insights into the excited-state dynamics of coumarin dyes C460 and C481 in various solvents.The results revealed that C481 predominantly undergoes the TICT process in highly polar methanol solvents with strong hydrogen-bonding capabilities.Furthermore,quantum chemical calculations indicated that introducing fluorine substitutions reduces the molecules'internal torsional barriers,leading to enhanced non-radiative deactivation processes and,consequently,more pronounced fluorescence quenching phenomena.This investigation provides insights into the selection of suitable solvents for optimizing the performance of fluorescent dyes and offers valuable guidance for their design.

关 键 词：瞬态吸收光谱 扭转分子内电荷转移 密度泛函理论 

分 类 号：O433.4[机械工程—光学工程]