Molecular architecture in cyanine dye aggregates at the air-water interface. Effect of monolayer composition and organization on fluorescent behavior
| Autor: | S. Vaidyanathan, D. Möbius, L. K. Patterson, H. R. Gruniger |
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| Rok vydání: | 1985 |
| Předmět: | |
| Zdroj: | The Journal of Physical Chemistry. 89:491-497 |
| ISSN: | 1541-5740 0022-3654 |
| DOI: | 10.1021/j100249a025 |
| Popis: | The fluorescence behavior of an amphiphatic oxacyanine dye and its thiacyanine analogue has been investigated in spread monolayers at the air-water interface. J-aggregate formation as a function of area/(dye molecule) was monitored by spectral changes in pure dye monolayers and in 1:1 mixtures of dye with various fatty acid coaggregates. Simultaneously, the thermodynamic behavior of these systems was characterized by the associated surface pressure-area isotherms. In all cases, J-aggregate formation may be related to a phase transition in the isotherm. The intensity of aggregate fluorescence is found to be inversely related to the work, ..delta..W, of compression of the monolayer through the transition. Inclusion of the fatty acid coaggregate was shown to facilitate J-aggregate formation in the order stearic > elaidic > oleic. Both fluorescence and thermodynamic data indicate more extensive aggregate formation in the thiacyanine systems. Aside from the paramount role played by the chromophore-chromophore interactions in determining J-aggregate phenomena, this study suggests important contributions from dispersion forces involving the long hydrocarbon moieties. 13 refs., 10 figs. |
| Databáze: | OpenAIRE |
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