Spectroscopic investigation of the interaction between crystal-violet and sodium dodecanoylsarcosinate

Abstract

ABSTRACT The interaction of Tris(4-(dimethylamino)phenyl)methylium chloride (crystal violet (CV)) – a triphenylmethane dye with sodium dodecanoylsarcosinate – an amino acid-based anionic surfactant has been studied with a view to investigate the effect of the surfactant on the spectral behaviours of the dye. The dye–surfactant interaction was studied spectrophotometrically in aqueous solutions, and the dye was found to strongly interact electrostatically and formed ion-pair complex with the anionic surfactant at the pre-micellar surfactant concentrations. This is evidenced from the marked changes in the spectral behaviour of the dye in the presence of the surfactant. The complex ion-pair appeared to self-aggregate at a critical aggregate concentration of 2.50 mM. At and above the critical micelle concentration (CMC) of the pure surfactant, the dye became completely solubilised in the micelle. The extent of dye–surfactant complex ion-pair formation in the pre-micellar region and the dye–micelle-binding constants were determined from the Rose–Drago equation.