Long-lived circularly-polarized phosphorescence in helicene-NHC-rhenium(I) complexes: The influence of helicene, halogen and stereochemistry on emission properties

Etienne S Gauthier (1, 2) , Laura Abella (3) , Nora Hellou (1, 2) , Benoît Darquié (4) , Elsa Caytan (1, 2) , Thierry Roisnel (1, 2) , Nicolas Vanthuyne (5) , Ludovic Favereau (1, 2) , Monika Srebro-Hooper (6) , J a Gareth Williams (7) , Jochen Autschbach (3) , Jeanne Crassous (1, 2)

1 ISCR - Institut des Sciences Chimiques de Rennes
2 ScanMAT - Synthèse Caractérisation Analyse de la Matière
3 SUNY - State University of New York
4 LPL - Laboratoire de Physique des Lasers
5 ISM2 - Institut des Sciences Moléculaires de Marseille
6 UJ - Uniwersytet Jagielloński w Krakowie = Jagiellonian University
7 Durham University

The first enantiopure chiral-at-rhenium complexes of the form fac-ReX(CO) (:C^N) have been prepared, where :C^N is a helicene-N-heterocyclic carbene (NHC) ligand and X=Cl or I. These have complexes show strong changes in the emission characteristics, notably strongly enhanced phosphorescence lifetimes (reaching 0.7 ms) and increased circularly polarized emission (CPL) activity, as compared to their parent chiral models lacking the helicene unit. The halogen along with its position within the dissymmetric stereochemical environment strongly affect the photophysics of the complexes, particularly the phosphorescence quantum yield and lifetime. These results give fresh insight into fine tuning of photophysical and chiroptical properties of Re-NHC systems.

Keywords: rhenium(I); long-lived phosphorescence; helicene; circularly polarized emission; N-heterocyclic carbene

Domains: Chemical Sciences

Etienne S Gauthier, Laura Abella, Nora Hellou, Benoît Darquié, Elsa Caytan, et al.. Long-lived circularly-polarized phosphorescence in helicene-NHC-rhenium(I) complexes: The influence of helicene, halogen and stereochemistry on emission properties. Angewandte Chemie International Edition, 2020, 59 (22), pp.8394-8400. ⟨10.1002/anie.202002387⟩. ⟨hal-02533163⟩