Enantiopure, luminescent, cyclometalated Ir() complexes with N-heterocyclic carbene-naphthalimide chromophore: design, vibrational circular dichroism and TD-DFT calculations

• Published in: Dalton transactions : an international journal of inorganic chemistry 2022-02, Vol.51 (7), p.275-2759
• Main Authors: Groué, Antoine, Montier-Sorkine, Eve, Cheng, Yaping, Rager, Marie Noelle, Jean, Marion, Vanthuyne, Nicolas, Crassous, Jeanne, Lopez, Amalia C, Saavedra Moncada, Alejandra, Barbieri, Andrea, Cooksy, Andrew L, Amouri, Hani
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Chromophores; Column chromatography; Dichroism; Enantiomers; Iridium compounds; Mathematical analysis; Stereochemistry
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d1dt04006e

A series of chiral cyclometalated iridium complexes of the type [Ir(C^N) 2 (C^C:)], {(C^N) = ppy ( 2 ); dfppy ( 3 )} featuring a naphthalimide N-heterocyclic carbene ligand (C^C:) = (Naphthalimide-NHC) are described and fully characterized. The racemic complexes rac - 2 and rac - 3 were resolved via chiral column chromatography techniques into their corresponding enantiopure species Δ - 2 , Λ - 2 , Δ - 3 , Λ - 3 as confirmed by their CD curves. This unique class of molecules containing organic and inorganic chromophores might be used as a platform to probe the stereochemical effect on the photophysical properties. Vibrational circular dichroism (VCD) was used as an important tool to assign successfully the stereochemistry of the enantiomers. TD-DFT calculations are also advanced to support the experimental studies and to rationalize the observed results. Chiral [Ir(N^C) 2 (C^C:)] complexes are described. At room temperature they act as emitters in the red and NIR regions. Their optical and chiroptical properties were studied. Remarkably VCD and TD-DFT allow us to ascertain their stereochemistry.