Photophysics Laboratory, Department of Physics, Centre of Advance Study, DSB Campus, Kumaun University, Nainital 263002, India.
Laser Spectroscopy Laboratory, Department of Applied Physics, Delhi Technological University, Bawana Road, Delhi 110042, India.
Methods Appl Fluoresc. 2023 Jul 7;11(4). doi: 10.1088/2050-6120/ace152.
The present work investigated the influence of different halides on the excited state dynamics of 6-methoxyflavone (6MF) in an aqueous solution with steady-state and time-resolved techniques. On successive addition of Iand Brions, the fluorescence of 6MF quenched significantly, whereas the respective ions do not change the maximum fluorescence band. Fluorescence of 6MF was quenched 66% by Iions and 34% by Brions. In a pure aqueous medium, both the H-bonded: CT and protonated species of 6MF participate in the quenching of fluorescence. The quenching process was categorized by Stern-Volmer (S-V) and Lehrer equations. Quenching parameters such as K, Kand kwere higher for Iions than Brions. The decrease in fluorescence intensity and a reduction in fluorescence lifetime suggested the dynamic nature of quenching by Iions following the electron transfer mechanism. Fluorescence quenching of 6MF has also been observed in the acidic medium in the presence of different halides. Thus, the study reveals that 6MF is responsive towards Iions in a wide range of pH, specifically in a purely aqueous environment (pH∼7), hence important for sensing/detection applications.
本工作采用稳态和时间分辨技术研究了不同卤素离子对水相体系中 6-甲氧基黄酮（6MF）激发态动力学的影响。随着 I- 和 Br- 离子的连续加入，6MF 的荧光显著猝灭，而相应的离子并不改变最大荧光带。I- 离子猝灭了 6MF 荧光的 66%，而 Br- 离子猝灭了 34%。在纯水溶液中，6MF 的氢键：CT 和质子化物种都参与了荧光的猝灭。猝灭过程可以用 Stern-Volmer（S-V）和 Lehrer 方程进行分类。与 Br- 离子相比，I- 离子的猝灭参数 K、Kq 和 kw 更高。荧光强度的降低和荧光寿命的缩短表明，I- 离子通过电子转移机制进行动态猝灭。在酸性介质中存在不同的卤素离子时，也观察到了 6MF 的荧光猝灭。因此，该研究表明 6MF 对 pH 值范围很广的 I- 离子有响应，特别是在纯水溶液环境（pH∼7）中，因此在传感/检测应用中非常重要。
