Electroactive deposits of anthraquinone-attached micelle- and vesicle-forming surfactant assemblies on glassy carbon surfaces

Abstract

Three cationic surfactants with covalently attached anthraquinone moieties at the headgroup region, 1-3, were synthesized. The single chain surfactant, N,N-dimethyl-N-octadecyl-N-((9,10-dihydro-9,10-dioxoanthracen-2-yl)methyl)ammonium bromide, 1, upon comicellization with cetyltrimethylammonium bromide (CTAB) in water gave micellar aggregates with anthraquinone residues attached at the exposed aqueous interfaces. The two double chain amphiphiles, N,N-dioctadecyl-N-methyl-N-((9,10-dihydro-9,10-dioxoanthracen-2-yl)methyl)ammonium bromide, 2, and N,N-dimethyl-N-(1,2-bis(palmitoyloxy)propanyl)-N-((9,10-dihydro-9,10-dioxoanthracen-2-yl)methyl)ammonium bromide, 3, however, on suspension with either dioctadecyldimethylammonium bromide (DODAB) or alone in aqueous media gave vesicular assemblies with anthraquinone residues attached both at the inner and at the outer aqueous vesicular surfaces. Holomicellar 1 or comicellar 1/CTAB deposited on to the glassy carbon electrode surface during cyclic voltammometric studies. Above their critical temperatures for the gel to liquid-crystalline-like phase transitions, the vesicular systems also formed electroactive layers on glassy carbon electrodes. In this paper, we present in detail various electrochemical aspects concerning these anthraquinone aggregates and the role of introduction of electrochemically inert cosurfactants in the formation of such electroactive deposits.