Oxidative electrofluorochromism of rhodamine in electropolymerized rhodamine-carbazole dyads

A rhodamine-carbazole dyad has been synthesized and electropolymerized to generate thin films. The spectroelectrochemical properties of the resulting polymer are investigated both in absorption and emission. We show that the luminescence of the rhodamine unit is partially quenched by the carbazole moiety and this quenching is strongly enhanced upon oxidation. A reversible switch of the emission intensity between two redox states is demonstrated, but the stability is strongly dependent on the film thickness and proportion of carbazole in the polymerization medium. This luminescence quenching can be used to follow the electropolymerization reaction since a strong decrease of intensity occurs as soon as the oxidative coupling reaction starts.