New [4]helicene derivatives: Synthesis, characterization and photophysical properties

The design and synthesis of new [4]helicene derivatives were carried out by incorporating well-defined electron donor and acceptor groups at selected positions of the aromatic nuclei, aiming to use them in optical applications. Helicenes have been obtained in good overall yields through a five-step sequence involving mild experimental conditions and easy purification. Photophysical properties of these tetracyclic systems have been evaluated by UV–visible absorption and fluorescence spectroscopies and an emission in the visible region was observed. [Display omitted] •Facile method was developed for [4]helicenes preparation from 2-naphthaldehyde.•Photophysical properties of [4]helicenes were studied in solutions.•Optical gap values of [4]helicenes were found to be less than 3.2 eV.