Flavyliumsalze als Sonden zur Charakterisierung anionischer Tensidlösungen

Abstract

Flavylium Salts as Probes for the Characterization of Anionic Micelles Flavylium salts are suitable probe molecules for the fluorimetric investigation of the critical micelle concentration (CMC); for the absorption‐spectroscopic investigation of the surface potential; and also the microacidity in the Stern‐layer of anionic micelles. The reaction rates of the hydrolytic cleavage of the 7‐hydroxy‐4′‐methoxyflavyliumion 1a and the equilibrium between 1a and the 2,4‐dihydroxy‐4′‐methoxychalcone 5a formed were studied in acidic water solutions and in micellar surfactant solutions. Both measurements resulted in comparable values of the microacidity on the surface of the sodium dodecylsulfate micelles (SDS). The calculated surface‐potential of SDS‐micelles corresponds to literature data. The surface‐potentials of p‐dialkylbenzenesulfonate micelles (p‐DABS) depend on the structure of these surfactants in a characteristic manner.