Chiral organometallic systems
Keywords : organometallic helicenes, chiroptical switches, circularly polarized luminescence, optoelectronic devices, fundamental chirality
The molecular engineering consisting of using the chemistry of metallic ions combined with the chemistry of helicenes gives access to original helical pi-conjugated structures showing great potential as chiral molecular materials for opto-electronic applications (Chem. Rev. 2019, 119, 8846). Such strategy allows the development of helical ligands incorporating diverse complexing units (ligands of phenyl-pyridine, bipyridine, terpyridyne, heterocyclic carbene, alcynyl type) and the study of their stereocontrolled coordination together with their resulting physico-chemical properties. We have thus prepared i) helicene-alkynyl-iron complexes with chiroptical switching properties (reversible tuning of their circular dichroism, optical rotation or Raman Optical Activity) and modifications in the telecommunication domain (Coll. F. Paul, J. Casado, M. Vallet, Angew. Chem. Int. Ed. 2016, 55, 8062), ii) helicene-NHC-iridium complexes with long-lived and circularly polarized phosphorescence (see figure, Coll. J. A. G. Williams, L. Di Bari, Angew. Chem. Int. Ed. 2017, 56, 8236), or iii) helicenic bipyridine-type systems with chiroptical tuning mediated by zinc coordination (J. Org. Chem. 2019, 84, 5383). Furthermore, fundamental chirality-related aspects such as parity violation effects in chiral molecules are examined in model chiral organometallic complexes (Coll. B. Darquié, Chirality 2018, 30, 147). All these studies are performed in close collaboration with theoreticians (M. Srebro-Hooper, J. Autschbach), a specialist of chiral separations (N. Vanthuyne) (ANR MetalHel), and more specific partners (ANR HEL-NHC, coll. V. César, M. Mauduit).