A new pyrene-based fluorescent probe for the determination of critical micelle concentrations.
ABSTRACT A new pyrene-based fluorescent probe for the determination of critical micelle concentrations (CMC) is described. The title compound 1 is obtained in five steps, starting from pyrene. Fluorescence spectroscopic properties of 1 are studied in homogeneous organic solvents and aqueous micellar solutions. In a wide range of organic solvents, probe 1 exhibits a characteristic monomer emission of the pyrene fluorophore, with three distinct peak maxima at 382, 404, and 425 nm. The spectra change dramatically in aqueous solution, where no monomer emission of the pyrene fluorophore is detected. Instead, only strong excimer fluorescence with a broad, red-shifted emission band at lambda(max) = 465 nm is observed. In micellar aqueous solution, a superposition of the monomer and excimer emission is found. The appearance of the monomer emission in micellar solution can be explained on the basis of solubilization of 1 by the surfactant micelles. The ratio of the monomer to excimer fluorescence intensities of 1 is highly sensitive to changes in surfactant concentration. This renders 1 a versatile and sensitive probe molecule for studying the micellization of ionic and nonionic surfactants. For a representative selection of common surfactants, the critical micelle concentrations in aqueous solution are determined, showing excellent agreement with established literature data.
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ABSTRACT: Liquid surface curvature variations in microplate wells due to different liquid surface tension cause significant signal change in spectroscopic measurement using a plate reader with a vertical detecting light beam. The signals have been quantitated and used to develop a method for facile surfactant critical micelle concentration determination.Chemical Communications 04/2011; 47(19):5527-9. · 6.38 Impact Factor
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ABSTRACT: The synthesis and the structural and spectroscopic characterization of nonfluorescent, pyrene-based cyclic o-quinodimethanes are reported. These compounds react efficiently with nitric oxide (NO) in a formal cheletropic manner, by which the fluorescent aromatic pyrene system is regenerated. The NO trapping capabilities and kinetics of the fluorescent nitric oxide cheletropic traps (FNOCTs) are assessed in THF and buffered aqueous solution by ESR, UV/Vis, and fluorescence spectroscopy, by employing NO solutions and NO released from N-diazeniumdiolates (NONOates). Prototypal biological applications include the quantitation of NO production from cultured rat alveolar macrophages and the endothelium of porcine aorta, which demonstrate a sensitivity for NO detection in the nanomolar range.Chemistry 09/2010; 16(36):11121-32. · 5.93 Impact Factor
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ABSTRACT: A novel macromonomer: p-vinylbenzyl-terminated octylphenoxy poly(ethylene oxide) (VBE, polymerization degree: 24) was copolymerized with acrylamide (AM) and sodium 2-acrylamido-2-methylpropane-sulphonate (NaAMPS) to form a water-soluble terpolymer (abbreviation: PAAB). It exhibited remarkable surface and interface activities as well as a thickening effect in unsalted and brine solutions. The variation of surface and interface tensions with NaCl concentration was investigated; the interface tensions in water and in a 70 g L NaCl solution were, respectively, 4.1 mN m and 2.3 mN m at a polymer concentation of 0.1 g dL. The intermolecular hydrophobic associations in unsalted and brine PAAB solutions as a function of polymer concentration, and the conformation of polymer chains were characterized by a fluorescent probe. The results indicated that the incorporation of long side chains could expand the polymer chains in brine solutions as well as in the unsalted solutions. The probe investigation in the unsalted and brine polymer solutions also showed that the extended mono-molecules were dominant at the polymer concentrations lower than 0.05 g dL, and that the intermolecular hydrophobic associations were enhanced sharply above the critical association concentrations of 0.10 g dL.Journal of Macromolecular Science, Part B. 01/2012;