Influence of mixed cationic-nonionic surfactant systems on the spectral properties of C.I. Mordant Blue 29 and its complexes with iron(III).

Interactions of the anionic form of C.I. Mordant Blue 29 with cationic and nonionic surfactants have been studied by absorption spectroscopy. The dye interacts strongly with oppositely charged surfactants in the pre-micellar concentration range with an accompanying change in its spectral properties, while its interaction with the polyoxyethylene group of nonionic surfactants does not have such remarkable effects. In ternary mixtures, however, the influence of the polyoxyethylene group on the optical properties of C.I. Mordant Blue 29-tetradecyltrimethylammonium bromide and C.I. Mordant Blue 29-octadecyltrimethylammonium chloride systems is quite different. In addition, the influence of the interaction between the HL(3-) form of C.I. Mordant Blue 29 and the surfactants on the formation of chelate complexes with iron(III) has been studied. The optimized structures of Fe-Mordant Blue 29 complexes are also reported herein. Geometries have been calculated by the Hartree-Fock method with the cc-pVDZ basis set.