Resolution of 9,10-Diketo[7]helicene and Its Use in One-Step Preparation of Helicene-Based D−A−D Push-Pull Systems

Research of chiral push-pull systems based on helicenes continues successfully in the Group of Advanced Materials and Organic Synthesis (GAMOS). This type of molecules, containing one or more electron-rich (donor, D) and electron-deficient (acceptor, A) groups directly connected to the π-system of helicene, is suitable for the preparation of luminescent materials and possibly for the construction of light-emitting devices on their base. An added value in the case of using helicenes is their chirality, which can lead to the emission of circularly polarized light and, thus, a significant increase in the application potential of this group of substances.

The latest paper, which was published in The Journal of Organic Chemistry, builds on our previous research on 9,10-diketo[7]helicene. In this study, this versatile starting material was separated into enantiomers by reaction with a chiral reagent, which represents a significant amount of material and time savings compared to conventional separation on chiral chromatographic columns. The diketone thus divided was subjected to a reaction with suitably substituted diaminobenzenes, which led to the formation of a series of several D-A-D push-pull systems, i.e. substances bearing two electron-rich groups directly attached to an electron-deficient group. The properties of these compounds were studied by various spectroscopic or DFT methods and were subsequently compared with the properties of reference compounds. Further measurements then proved that these substances reach typical absorption values of circularly polarized light (g_abs). Moreover, this absorption is active only for transitions between orbitals lying directly on the helicene molecule, which is essential information for further design of similar compounds.

• Kos M., Beránek T., Císařová I., Cuřínová P., Žádný J., Storch J., Církva V., Jakubec M.*: Resolution of 9,10-Diketo[7] helicene and Its Use in One-Step Preparation of Helicene-Based D−A−D Push-Pull Systems. J. Org. Chem. 2024, 89(11), 7495-7502. doi.org/10.1021/acs.joc.4c00135