Synthesis, electrochemical and spectroscopic investigations of New N-BEDOT derivatives containing anil substituted carbazole subunits

A conjugated oligomer containing central bi-ethylenedioxythiophene (BEDOT) unit and two terminal anil-substituted carbazole units has been characterized by cyclic voltammetry and spectroelectrochemical methods (UV–vis–NIR and Raman). It shows two oxidation waves at −0.01 V and +0.24 V (versus Fc/Fc+), which can be ascribed to two successive oxidative dopings of the molecule. The molecule is transmissive sharp yellow when fully reduced, transmissive green upon oxidation up to the end of the first oxidative process, and dark blue upon full oxidation. UV–vis–NIR and Raman spectroelectrochemical investigations show that the colour changes within the potential of the first oxidation wave are associated with the oxidation of both carbazole and ethylenedioxythiophene subunits whereas the electrochromic effect in the potential range of the second oxidation wave involves predominantly the oxidation of the ethylenedioxythiophene subunits.