Photoinduced Electron Transfer Reactions of Water Soluble Porphyrins in Zeolite Environment

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 (H 2...

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Bibliographic Details
Published in:Journal of fluorescence 2021-09, Vol.31 (5), p.1575-1585
Main Authors: Velappan, Kandavelu, Rajalingam, Renganathan, Venkattappan, Anbazhagan
Format: Article
Language:English
Subjects:
Analytical Chemistry
Antioxidants
Ascorbic acid
Biochemistry
Biological and Medical Physics
Biomedical and Life Sciences
Biomedicine
Biophysics
Biotechnology
Electron transfer
Excitation
Glutathione
Luminescence quenching
Original Article
Porphyrins
Quenching
Solvation
X ray powder diffraction
Zeolites
Zinc
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Summary: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 (H 2 TMPyP 4+ ) and zinc tetra( N -methyl-4-pyridyl) porphyrin (ZnTMPyP 4+ ) 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 0 /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 q ) is found in the order of 10 9  M −1  s −1 . 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).
ISSN:1053-0509
1573-4994
DOI:10.1007/s10895-021-02747-8