Wang Yuxi, Li Wenzhi, Zhou Panwang
Institute of Frontier Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Qingdao 266237, China.
Institute of Frontier Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Qingdao 266237, China; State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2024 Dec 15;323:124923. doi: 10.1016/j.saa.2024.124923. Epub 2024 Jul 31.
In vivo real-time detection of hypochlorous acid (HClO) in biological systems plays a crucial role in diagnosing immune-related diseases. Experimentally, a benzo-bodipy probe based on the photo-induced electron transfer (PeT) sensing mechanism has been developed for live fluorescence imaging. However, there have been no theoretical studies conducted to substantiate the precision of the sensing mechanism. This paper employs density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods to investigate the fluorescence detection mechanism of benzo-bodipy derivatives (BBy-T and BBy-TO), proposing a detection approach based on dark nπ* state quenching. The study reveals that the fluorescence quenching mechanism of BBy-T is primarily regulated by a thiomorpholine moiety, involving a dark nπ* state transition non-radiatively. Furthermore, this paper explains the fluorescence enhancement observed in BBy-TO. Theoretical investigations demonstrate, based on frontier molecular orbitals (FMOs) and hole-electron analysis, that the fluorescence enhancement for BBy-TO is not governed by the previously proposed intramolecular charge transfer (ICT) mechanism in experiments but rather follows a locally excited (LE) ππ* pattern. This work offers new insights for the design of novel fluorescence probes based on bodipy and benzo derivatives, expanding the understanding of their fluorescence properties.
生物系统中次氯酸（HClO）的体内实时检测在免疫相关疾病的诊断中起着至关重要的作用。在实验方面，基于光诱导电子转移（PeT）传感机制开发了一种苯并 - 硼二吡咯探针用于活体荧光成像。然而，尚未有理论研究来证实该传感机制的精确性。本文采用密度泛函理论（DFT）和含时密度泛函理论（TDDFT）方法研究苯并 - 硼二吡咯衍生物（BBy - T和BBy - TO）的荧光检测机制，提出一种基于暗nπ态猝灭的检测方法。研究表明，BBy - T的荧光猝灭机制主要受硫代吗啉部分调控，涉及暗nπ态的非辐射跃迁。此外，本文解释了在BBy - TO中观察到的荧光增强现象。基于前线分子轨道（FMOs）和空穴 - 电子分析的理论研究表明，BBy - TO的荧光增强并非由实验中先前提出的分子内电荷转移（ICT）机制所决定，而是遵循局域激发（LE）ππ*模式。这项工作为基于硼二吡咯和苯并衍生物的新型荧光探针设计提供了新的见解，扩展了对其荧光性质的理解。
