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7612783 
Journal Article 
PROTON NUCLEAR MAGNETIC-RESONANCE AND LASER PHOTOLYSIS STUDIES OF PYRENE DERIVATIVES IN AQUEOUS AND MICELLAR SOLUTIONS 
Gratzel, M; Kalyanasundaram, K; Thomas, JK; , 
1974 
Yes 
Journal of the American Chemical Society
ISSN: 0002-7863
EISSN: 1520-5126 
AMER CHEMICAL SOC 
WASHINGTON 
96 
26 
7869-7874 
English 
WOS:A1974V129400004 
Pulsed FT proton magnetic resonance measurements and chemical shift analysis have been carried out in order to determine the dynamic solubilization site of the pyrene chromophore in cationic micellar solutions of pyrene, pyrene butyric acid (PBA), and pyrene sulfonic acid (PSA). Pyrene is solubilized in the interior of cetyltrimethyl ammonium bromide (CTAB) micelles while the pyrene chromophore of PBA and PSA is located in the outer core and surface region of the micelle, respectively. PSA and PBA in aqueous and micellar solutions were excited with 347.1-nm ruby laser light. The fluorescence lifetime of PSA is 62 nsec in water and 140 or 30 nsec in micellar solution of dodecyltrimethyl ammonium chloride (DTAC) or CTAB; for PBA the respective values are 140, 200, and 158 nsec. These results are explained in terms of stabilization of the excited singlet states of the probes by the micellar environment and quenching by Br- counterions. For PBA the quenching efficiency of Br- is much lower than for PSA due to the larger separation of the pyrene ring from the micellar Stern layer. The 347.1-nm laser photolysis of PSA and PBA in water also produces a large yield of hydrated electrons via a biphotonic photoionization process. In the case of PSA the photoionization is strongly inhibited by cationic micelles. © 1974, American Chemical Society. All rights reserved.