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Effects of interaction with CTAB micelles on photophysical characteristics of meso-tetrakis(sulfonatophenyl) porphyrin

Paper ID Volume ID Publish Year Pages File Format Full-Text
28557 44080 2006 7 PDF Available
Title
Effects of interaction with CTAB micelles on photophysical characteristics of meso-tetrakis(sulfonatophenyl) porphyrin
Abstract

The whole set of photophysical characteristics of the metal-free water-soluble meso-tetrakis(p-sulfonatophenyl) porphyrin (TPPS4) in its protonated and nonprotonated states in homogeneous aqueous solutions and in the presence of cationic cetyltrimethylammonium bromide micelles (CTAB) was investigated with nonlinear optical Z-scan technique, UV–vis absorption and fluorescence spectroscopies, time-resolved fluorescence and flash-photolysis. The characteristics were: the cross-sections of the ground (σ0) and the excited singlet (σS) and triplet (σT) states; the rate constants of intersystem-crossing (kisc), internal conversion (kic) and radiative one (kr); the quantum yields (Φfl and ΦT) and lifetimes (τS and τT) of singlet and triplet states and quantum yield of internal conversion (Φic). The study was realized at pH 7.0 and 4.0, where TPPS4 in homogeneous solutions is nonprotonated and biprotonated, respectively. It was observed that, in spite of the fact that protonation changes all these characteristics, their values for TPPS4 bound with CTAB micelles were at both pH close to those of nonprotonated porphyrin in the solution. It is due to the fact that binding with CTAB shifts the pK of TPPS4 from 5.0 in homogeneous solution to 2.5 in the micellar one and the bound porphyrin appears in nonprotonated state at both pH used. We can conclude also that the change of the quality of the environment from homogeneous aqueous solution to the micellar one affects weakly the TPPS4 photophysical characteristics when it is not protonated.

Keywords
TPPS4 porphyrin; Photophysical characteristics; CTAB micelles; Fast optical limiters and switches; Photodynamic therapy
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Effects of interaction with CTAB micelles on photophysical characteristics of meso-tetrakis(sulfonatophenyl) porphyrin
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 181, Issues 2–3, 31 July 2006, Pages 378–384
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
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Don't Miss Today's Special Offer
Price was $35.95
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Price after discount Only $4.95
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