Aqueous Electrogenerated Chemiluminescence of Self-Assembled Double-Walled Tubular J-Aggregates of Amphiphilic Cyanine Dyes

This study investigates superradiant organic dye J-aggregates as a potential new class of aqueous luminophores for electrogenerated chemiluminescence (ECL). Simultaneous cyclic voltammograms (CVs) and ECL transients are obtained from the self-assembled double-walled tubular J-aggregates formed from the amphiphilic cyanine dye 3,3'-bis(2-sulfopropyl)-5,5',6,6'-tetrachloro-1,1'-dioctylbenzimidacarbocyanine (C8S3) immobilized on glassy carbon electrodes in the presence of the oxidative-reductive coreactant 2-(dibutylamino)ethanol (DBAE). ECL is produced by both the direct oxidation of DBAE at the electrode and the catalytic oxidation of DBAE by the C8S3 J-aggregates. Optimization studies of the DBAE concentration and pH of the electrolyte show the most intense ECL signal was obtained with similar to 17 mM DBAE as coreactant (saturated solution in 1M KNO3) at pH 12.85, an effect of DBAE solubility and pK(a). The overlaid ECL spectrum and the fluorescence spectrum were in good agreement, confirming that the ECL emission is associated with the singlet exciton delocalized on the tubular C8S3 J-aggregates. Amphiphilic J-aggregates are promising new systems for ECL applications because of their unique characteristics such as accessible redox chemistry in the aqueous potential window, increased fluorescence emission, and narrow emission lines.