Redox and optically active carbohelicene layers prepared by potentiodynamic polymerization

Abstract

This short paper describes the preparation of thin layers based on carbohelicenes, which are inherently chiral polyaromatics existing in the enantiomeric forms P and M. Specifically, [5]-, [6]- and [7]helicene were subjected to redox cycling between -1.5 and 1.5 V vs. ferrocene/ferrocenium at a scan rate of 10 V/s. This way, enantiopure layers exhibiting redox activity were formed on the surfaces of the glassy carbon and ITO electrodes under anoxic and non-aqueous conditions. The properties of the prepared polymer layers were investigated using electrochemistry with Fe/Ru redox probes, circular dischroism, AFM, impedance measurement and Raman spectroscopy. With [6]helicene, the suggested electropolymerization procedure thus represents a proof-of-concept for the preparation of chiral carbonaceous surfaces.