In Situ Electrochemical Investigations of Inherently Chiral 2,2′-Biindole Architectures with Oligothiophene Terminals

The synthesis and characterization of three new inherently chiral N,N′-dipropyl-3,3′-diheteroaryl-2,2′-biindole monomers, nicknamed Ind2T4, Ind2T6 and Ind2Ph2T4, which differ in the number of thiophenes as terminals, are reported. In addition to a full monomer characterization, stable electroactive oligomeric films were obtained by electro-oxidation upon cycling to potentials which activate the thiophene terminals. Cyclic voltammetry, UV-Vis-NIR spectroelectrochemistry and in situ conductance measurements show that oligomeric films of Ind2T6 present the best stability and electrochromic switching performance. Enantioselective tests with a chiral ferrocene amine clearly show the potential as chiral selectors for analytical and sensing purposes.