Synthesis and characterization of new helically chiral heptacyclic systems

Abstract

New helically chiral heptacyclic systems with cyano groups at selected positions have been synthesized in good yields, via a four-step sequence, from readily available materials. The optical properties of the target helicenes were investigated by UV–visible absorption and photoluminescence spectroscopy and an emission in the visible region was observed. The energy levels of these organic materials were determined by cyclic voltammetry and showed a relatively high electronic affinity, indicating that they may be good candidates for electron-injection hole blocking layer in organic light-emitting diodes.