INTERFACIAL PROPERTIES OF A NOVEL GROUP OF SOLVATOCHROMIC ACID-BASE INDICATORS IN SELF-ASSEMBLED SURFACTANT AGGREGATES

Article abstract of DOI:10.1021/j100320a042

The spectral and acid-base properties of 1-hexadecyl-4-<(oxocyclohexadienylidene)ethylidene>-1,4-dihydropyridine (HOED), 1-hexadecyl-5-hydroxyquinoline (H5HQ), and 1-hexadecyl-6-hydroxyquinoline (H6HQ) have been investigated to ascertain their suitability as probes of both the mean interfacial solvent properties and the electrostatic surface potential of self-assembled surfactant aggregates in aqueous solution.The results obtained indicate that the solvatochromic visible absorption band of the conjugate base form of HOED, H5HQ, and H6HQ can be utilized to obtain a resonable estimate of the mean interfacial solvent properties of self-assembled surfactant aggregates.The factors that are primarily responsible for the apparent pK_a values of HOED, H5HQ, and H6HQ in most types of self-assembled surfactant aggregates have been ascertained.It is concluded that the acid-base properties of HOED, H5HQ, and H6HQ can be utilized to obtain a quantitative measure of the electrostatic surface potential of self-assembled surfactant aggregates in aqueous solution.