Photophysical and photochemical properties of rhodamine 6G in alcoholic and aqueous sodium dodecylsulphate micellar solutions
ABSTRACT The photodecomposition of the rhodamine 6G (R6G) dye dissolved in n-alcohols and aqueous sodium dodecylsulphate (SDS) micellar solution was investigated under continuous UV-visible illumination. The results indicate that in alcohol solution the photodecomposition efficiency increases with the dye concentration. It also depends on the nature of the alcohol the lowest efficiency being observed in ethyleneglycol. The mechanism involves the electron transfer reaction of the triplet excited state with a ground state dye molecule (T + S0 → R+ + R−. In aqueous SDS micellar solution, the R6G cation is embedded in the hydrophobic interior of the micelle close to the negatively charged sulphate end groups. We show that a rather high concentration (3 × 10−3 M) of R6G can be dissolved in 10−1 M SDS aqueous solution, protecting R6G from the electron transfer reaction and secondary decomposition reactions.
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ABSTRACT: Polypropylene supports were functionalized by plasma-deposition of polymeric allylamine layers. The surface amino groups generated were wet-chemically reacted with xanthene dyes resulting in fluorescent polymer films. The effect of polymer-attachment of the dyes on their emission features was studied fluorometrically and different methods were tested to improve the fluorescence properties of the films. Modification with cucurbituril (CB6) yields a moderately enhanced fluorescence as well as an improved photostability. The observed effect is most likely due to CB6-induced rigidization of the linker molecules which seems to reduce fluorescence quenching dye-dye and fluorophore-surface interactions.Journal of Fluorescence 09/2008; 19(2):229-37. · 1.79 Impact Factor
- Journal of The Ceramic Society of Japan - J CERAMIC SOC JPN. 01/2008; 116(1352):555-560.
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ABSTRACT: In this paper we introduce a methodology to encapsulate hydroxy pyrene trisulfonate (HPTS) inside the microcapsules and carry out spectroscopic and fluorescence lifetime studies of these encapsulated HPTS. The synthesis of microcapsule encapsulating HPTS was achieved using poly-L-lysine, trisodium citrate and silica sol and characterized by scanning electron microscopy (SEM), confocal and optical microscopy. The spectroscopic evaluation of encapsulated HPTS showed completely different but more-stable optical properties by lowering the energy gap between the excited and ground state. A single-exponential prolonged fluorescence lifetime upon encapsulation of probe inside the microcapsule compared to pyrene was obtained, by improving de-quenching by molecular oxygen in the solution. Based on a solvatochromic study, a higher polarizability was recorded inside the microcapsule. Temporal evolution under continuous irradiation indicates that the probe present inside the silica microcapsule is highly photostable compared to pyrene in solution, suggesting that the microcapsule can provide extra photochemical stability to not only the probe molecule during molecular sensing, but also the guest (drug) molecule while applied as drug delivery system.Journal of Materials Chemistry 01/2009; 19(23). · 5.97 Impact Factor