Aggregation of amphiphilic pyranines in water : facile micelle formation in the presence of methylviologen
Four amphiphilic pyranines in which the acidic hydrogen of pyranine was replaced by an octyl, dodecyl, hexadecyl, and eicosyl group, POCn (n=8, 12, 16, and 20), were prepared, and their spectroscopic properties and aggregation behaviors in water were investigated. The critical micelle concentration...
| Publié dans: | Langmuir : the ACS journal of surfaces and colloids. - 1991. - 24(2008), 6 vom: 18. März, Seite 2387-94 |
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| Autres auteurs: | |
| Format: | Article en ligne |
| Langue: | English |
| Publié: |
2008
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| Accès à la collection: | Langmuir : the ACS journal of surfaces and colloids |
| Sujets: | Journal Article Research Support, Non-U.S. Gov't Arylsulfonates Micelles Water 059QF0KO0R pyranine I2W85YOX9L Paraquat PLG39H7695 |
| Résumé: | Four amphiphilic pyranines in which the acidic hydrogen of pyranine was replaced by an octyl, dodecyl, hexadecyl, and eicosyl group, POCn (n=8, 12, 16, and 20), were prepared, and their spectroscopic properties and aggregation behaviors in water were investigated. The critical micelle concentration (cmc) of the amphiphilic pyranines was found to be relatively large even in POC20 having a long hydrophobic alkyl chain (ca. 3x10(-3) M). 1H NMR studies revealed that POC16 and POC20 exist in the compact structure with the pyranine nucleus wrapped with a long methylene chain in water. As in the case of parent pyranine, the addition of methylviologen (MV2+) to an aqueous solution of POCn resulted in the absorption spectral change and efficient quenching of POCn fluorescence. In the case of POC8 and POC12, these spectral changes induced by the MV2+ addition were thoroughly explained in terms of the formation of the electrostatic complex POCn/MV2+ with a complexation constant of approximately 3x10(4) M(-1). On the other hand, an unexpectedly large dependence of the absorption spectral change, as well as fluorescence quenching, on the total concentration of MV2+ was observed in POC16 and POC20. The Stern-Volmer plot for quenching of the fluorescence of POC16 and POC20 gave a curve deviating largely upward from a straight line. The plot was successfully analyzed by the equation induced by assuming the aggregate formation of the complex POCn/MV2+, which revealed the considerably small cmc values of the complexes, 3.6x10(-7) and 3.6x10(-8) M for POC16/MV2+ and POC20/MV2+, respectively. Experimental evidence in support of the aggregate formation was obtained by 1H NMR and dynamic light scattering studies |
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| Description: | Date Completed 14.05.2008 Date Revised 24.11.2016 published: Print-Electronic Citation Status MEDLINE |
| ISSN: | 0743-7463 |
| DOI: | 10.1021/la702849c |