School of Chemistry, Bharathidasan University, Tiruchirappalli, Tamil Nadu, 620 024, India.
Department of Chemistry, Vinayaka Mission's Kirupananda Variyar Arts and Science College, Vinayaka Missions Research Foundation (Deemed to be University), Salem, Tamil Nadu, 636 308, India.
J Fluoresc. 2021 Sep;31(5):1575-1585. doi: 10.1007/s10895-021-02747-8. Epub 2021 Aug 2.
Excited state interactions of zeolite adsorbed porphyrins have been investigated by steady state luminescence quenching technique with certain antioxidants such as reduced glutathione, ascorbic acid and L-cysteine. The zeolite supported porphyrins, meso-tetra (N-methyl-4-pyridyl) porphyrin (HTMPyP) and zinc tetra(N-methyl-4-pyridyl) porphyrin (ZnTMPyP) were prepared and characterized by various techniques such as Diffuse Reflectance Spectra (DRS), Scanning Electron Microscope (SEM), powder X-Ray Diffraction (XRD) and BET surface area. The interaction of zeolites with porphyrins are shown to increase the lifetime of the singlet excited state of porphyrins and decays are biphasic in nature. The splitting of the emission band of porphyrins occurs in 1:1 glycerol: water solution due to the changes in the dielectric of the solvation sphere associated with porphyrin. The Stern-Volmer plots of I/I vs quencher concentration [Q] were linear in the whole range of [Q] used. These studies revealed the effective quenching for zinc porphyrin compared to free base porphyrin. The effect of quenchers and zeolite acidity has also been studied and the quenching rate constant (k) is found in the order of 10 M s. The quenching reaction obeys Rehm-Weller Equation and is shown to be due to thermodynamically favoured electron transfer from quenchers to the excited singlet state of porphyrins (reductive quenching).
通过稳态荧光猝灭技术，研究了沸石吸附卟啉的激发态相互作用，使用了一些抗氧化剂，如还原型谷胱甘肽、抗坏血酸和 L-半胱氨酸。沸石负载卟啉，meso-四（N-甲基-4-吡啶基）卟啉（HTMPyP）和锌四（N-甲基-4-吡啶基）卟啉（ZnTMPyP）通过漫反射光谱（DRS）、扫描电子显微镜（SEM）、粉末 X 射线衍射（XRD）和 BET 表面积等多种技术进行了制备和表征。结果表明，沸石与卟啉的相互作用增加了卟啉的单重激发态的寿命，且衰减呈双相性。由于与卟啉相关的溶剂化球介电常数的变化，卟啉的发射带在 1:1 甘油：水溶液中发生分裂。I/I 与猝灭剂浓度[Q]的 Stern-Volmer 图在整个[Q]范围内呈线性关系。这些研究表明，锌卟啉比自由碱基卟啉的有效猝灭。还研究了猝灭剂和沸石酸度的影响，发现猝灭速率常数（k）的顺序为 10 M s。猝灭反应符合 Rehm-Weller 方程，表明是由于从猝灭剂到卟啉的激发单重态的热力学有利的电子转移（还原猝灭）。
