Photoreaction of Thioxanthone with Indolic and Phenolic Derivatives of Biological Relevance: Magnetic Field Effect Study

The photoinduced reaction of thioxanthone (TX) with various indolic and phenolic derivatives and amino acids like tryptophan and tyrosine has been monitored in sodium dodecyl sulfate micellar medium. Laser flash photolysis and magnetic field effect (MFE) experiments have been used to study the dynam...

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Bibliographic Details
Published in:The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2008-11, Vol.112 (46), p.11619-11626
Main Authors: Das, Doyel, Nath, Deb Narayan
Format: Article
Language:English
Subjects:
A: Kinetics, Spectroscopy
Absorption
Amino Acids - chemistry
Animals
Cattle
Electron Transport
Indoles - chemistry
Magnetics
Micelles
Phenol - chemistry
Photochemical Processes
Protein Binding
Serum Albumin, Bovine - chemistry
Sodium Dodecyl Sulfate - chemistry
Surface-Active Agents - chemistry
Thioxanthenes - chemistry
Time Factors
Xanthones - chemistry
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Summary:The photoinduced reaction of thioxanthone (TX) with various indolic and phenolic derivatives and amino acids like tryptophan and tyrosine has been monitored in sodium dodecyl sulfate micellar medium. Laser flash photolysis and magnetic field effect (MFE) experiments have been used to study the dynamics of the radical pairs. The quenching rate constant with different quenchers in SDS micellar solution has been measured. For indoles the electron-transfer reaction has been found to be followed by proton transfer from the donor molecule, which gives rise to the TX ketyl radical. On the other hand, the electron-transfer reaction in the case of phenols is preceded with formation of a hydrogen-bonded exciplex. The extent of the MFE and magnitude of the magnetic field corresponding to one-half of the saturation value of MFE (B 1/2) support the fact that hyperfine mechanism plays the primary role. Quenching of MFE in the presence of gadolinium ions confirms that the radical pair is located near the micellar interface. MFE study has been further extended to protein-like bovine serum albumin in micellar solution. The results indicate loss in mobililty of radical pairs in the protein surfactant complex.
ISSN:1089-5639
1520-5215
DOI:10.1021/jp806880s