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Micelles as Containers for Self‐Assembled Nanodevices: A Fluorescent Sensor for Lipophilicity
Author(s) -
Chirico Giuseppe,
Collini Maddalena,
D'Alfonso Laura,
Denat Franck,
DiazFernandez Yuri A.,
Pasotti Luca,
Rousselin Yoann,
Sok Nicolas,
Pallavicini Piersandro
Publication year - 2008
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200800292
Subject(s) - lipophilicity , micelle , fluorescence , self assembly , nanotechnology , chemistry , materials science , organic chemistry , aqueous solution , physics , quantum mechanics
Potentiometric titrations, fluorescence versus pH titrations, dynamic light scattering and fluorescence polarization anisotropy studies demonstrate that inside the nanodimensioned Triton X‐100 micelles, 1‐pyrenecarboxylic acid, PCOO − , forms an apical complex with the Zn 2+ cation encircled by a lipophilic cyclen ligand and hugely increasing its fluorescence. The ability of the Zn 2+ ‐cyclen‐PCOO − complex plus its micellar container to act as a fluorescent sensor to evaluate the lipophilicity of molecular species is demonstrated on the fatty acid series CH 3 (CH 2 ) x COOH ( x =0–16). At pH 7.4 a decrease in fluorescence is observed on the addition of fatty acids that is directly related to their chain length, that is, to their tendency to enter the micellar containers, where they dislocate PCOO − from the Zn 2+ centre. The independent determination of fatty acid p K a values in the presence of Triton X‐100 micelles confirms that our fluorescent micellar device is capable of sensing their lipophilicity.