Modification of the Optical Properties of Helicenes using Push-Pull Systems Based on Phosphine Oxide

Non-planar polycyclic aromatic hydrocarbons have seen growing interest in recent years as alternatives to planar aromatics and nanographenes in a variety of applications. This is largely due to their convenient optical and electronic properties, different intermolecular interactions, or increased solubility. The effective use of these compounds requires a modification of a polyaromatic π-system and the formation of so-called push-pull systems. Such a system consists of one or more donor (D) and acceptor (A) groups connected by helicene as a suitable π-system. This study is being carried out by the Advanced Materials and Organic Synthesis Research Group, which recently published the issue in the journal Dyes and Pigments.

A series of [6]helicene-based push-pull systems bearing three diarylamines as donors and two phosphine-oxides as acceptors were designed and synthesized. The properties of these compounds were studied by various spectroscopic or DFT methods and were subsequently compared with the properties of reference compounds. Further investigation showed that the D-π-A system itself is the cause of the significant shift of fluorescence maxima. The obtained results suggest that phosphine oxide-based push-pull systems can significantly influence the electronic structure of helicenes and therefore increase their application potential.

Push-pull [6]helicenes

• Beránek, T.; Kos, M.; Váňa, L.; Císařová, I.; Sýkora, J.; Storch, J.; Církva, V.; Jakubec, M.: Modification of optical properties in helicenes via construction of phosphine oxide-based push-pull systems. Dyes Pigm. 2023, 210(February 2023), 111039 (13 pp). https://doi.org/10.1016/j.dyepig.2022.111039.