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 Ind(2)T(4), Ind(2)T(6) and Ind(2)Ph(2)T(4), 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 Ind(2)T(6) 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.

Automated summary

This study reports the synthesis and characterization of three new inherently chiral N,N'-dipropyl-3,3'-diheteroaryl-2,2'-biindole monomers, with Ind(2)T(6) showing the best stability and electrochromic switching performance in oligomeric films. Enantioselective tests with a chiral ferrocene amine demonstrate the potential of these monomers as chiral selectors for analytical and sensing purposes.