Twisting Light and Spin: Helicenes as Multifunctional Molecular Springs

Helicenes, with their characteristic corkscrew-shaped geometry, serve as versatile molecular scaffolds for constructing configurationally robust chiral functional materials through precise structural design. Ravat group focuses on leveraging this unique architecture to control electronic and (chir)optical properties at the molecular level.^[1] Specifically, the group aims to: (i) enhance long-range electronic communication in helicene-type systems by exploiting through-space conjugation, (ii) develop boron–nitrogen (B,N)-embedded helicenes that exhibit ultra-narrowband circularly polarized (CP) luminescence for CP-OLED applications, and (iii) employ helicenes as molecular synthon to construct helically twisted nanostructures in a stereospecific manner.

Dumele group^[2] has employed helicenes as building blocks for two-dimensional covalent organic frameworks (COFs), uncovering their crystalline order arising from homochiral (enantiopure) or racemic packing modes. This work has led to an unexpected discovery — the same [5]helicene can act as a photochemical spin-state switch, enabling reversible control of the magnetism with light.

Overall, this lecture will highlight how two distinct research directions converge when exploring related molecular scaffolds with wide-ranging applicability.

References:

[1] (i) Org. Lett. 2017, 19, 3707–3710; (ii) J. Am. Chem. Soc. 2020, 142, 21298–21303; (iii) Angew. Chem. Int. Ed. 2023, 62, e202218965. (iv) J. Am. Chem. Soc. 2024, 146, 29782–29791; (v) Angew. Chem. Int.Ed. 2025, 64, e202508779. [2] (i) J. Am. Chem. Soc. 2025, 147, 17750–17763; (ii) J. Am. Chem. Soc. 2022, 144, 8707–8716; (iii) Angew. Chem. Int. Ed. 2025, 64, e202512691; (iv) Angew. Chem. Int. Ed. 2025, early view, e202515144.