Modification of molecular properties of some dyes in sodium dodecyl sulphate (SDS) micellar aqueous solution.

The influence of SDS upon the molecular properties of proflavine (3,6-diaminoacridine), acridine yellow (2,7-dimethyl-3,6-diaminoacridine) and methylene blue (3,7-bis-dimethylamino-phenothiazine) was studied comparatively to their properties in that of aqueous media. The absorption and emission spectra of the three dyes in SDS aqueous solution (1-100 mmol/l) were recorded. The spectroscopic data also allowed the evaluation of the critical micellization concentration (CMC), acidity constants in fundamental (pk(a)) and excited (pK(*)(a)) states, and lifetimes of excited singlet states.

Spectroscopic study on nystatin conformational modifications generated by its interaction with the solvent.

Conformational transformations of the tetraenic nystatin chromophore under the influence of solvents and UV irradiation have been studied by absorption, fluorescence and wide-line NMR spectroscopy.