Zhang Qingqing, Li Shun, Qiu Xiaole, Yang Chuan-Lu
School of Physics and Electronic Information, Weifang University, Weifang, 261061, China.
School of Physics and Optoelectronic Engineering, Ludong University, Yantai, 264025, China.
J Fluoresc. 2025 May 22. doi: 10.1007/s10895-025-04376-x.
Excited state intramolecular proton transfer (ESIPT) process of a novel fluorescence probe 1 and its sensing mechanism for phosgene have been studied theoretically. The optimized geometric configurations and infrared spectroscopy analysis of probe 1 indicate that the intramolecular hydrogen bond (N-H···N) is strengthened upon excitation. Potential energy curves confirm that the energy barrier of probe 1 is smaller in the S state (6.21 kcal/mol) than that in the S state (15.47 kcal/mol), which promotes the occurrence of the ESIPT process. Theoretical calculations show that the absorption and fluorescence spectra of product are both red-shifted (91 and 77 nm, respectively) compared to the probe 1 due to the obvious charge transfer extent. The electron density difference indicates that the charge transfer distance of product (1.83 Å) is larger than that of probe 1 (1.49 Å), which results in the red-shift of emission of product compared to that of probe 1. Therefore, probe 1 can detect phosgene through the fluorescence variation induced by the large extent of charge transition. This work not only provides a theoretical foundation for designing ESIPT-based fluorescent sensors but also highlights their potential in real-time monitoring of toxic gases.
从理论上研究了新型荧光探针1的激发态分子内质子转移（ESIPT）过程及其对光气的传感机制。探针1的优化几何构型和红外光谱分析表明，激发时分子内氢键（N-H···N）增强。势能曲线证实，探针1在S态的能垒（6.21千卡/摩尔）比在S态的能垒（15.47千卡/摩尔）小，这促进了ESIPT过程的发生。理论计算表明，由于明显的电荷转移程度，产物的吸收光谱和荧光光谱与探针1相比均发生红移（分别为91和77纳米）。电子密度差表明产物的电荷转移距离（1.83 Å）大于探针1的电荷转移距离（1.49 Å），这导致产物的发射与探针1相比发生红移。因此，探针1可以通过由大量电荷跃迁引起的荧光变化来检测光气。这项工作不仅为设计基于ESIPT的荧光传感器提供了理论基础，也突出了它们在有毒气体实时监测中的潜力。
