Using substituted cyclometalated quinoxaline ligands to finely tune the luminescence properties of iridium(III) complexes

Langdon-Jones, Emily Elizabeth, Hallett, Andrew Jon, Routledge, Jack D., Crole, David Alexander, Ward, Benjamin David ORCID: https://orcid.org/0000-0003-1406-5940, Platts, James Alexis ORCID: https://orcid.org/0000-0002-1008-6595 and Pope, Simon J. A. ORCID: https://orcid.org/0000-0001-9110-9711 2013. Using substituted cyclometalated quinoxaline ligands to finely tune the luminescence properties of iridium(III) complexes. Inorganic Chemistr 52 (1) , pp. 448-456. 10.1021/ic301853t

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Abstract

The syntheses of five new heteroleptic iridium complexes [Ir(L1–4)2(Diobpy)]PF6 (where Diobpy = 4,4′-dioctylamido-2,2′-bipyridine) and [Ir(L3)2(bpy)]PF6 (where L = para-substituted 2,3-diphenylquinoxaline cyclometalating ligands; bpy = 2,2′-bipyridine) are described. The structures of [Ir(L3)2(Diobpy)]PF6 and [Ir(L3)2(bpy)]PF6 show that the complexes each adopt a distorted octahedral geometry with the expected trans-N, cis-C arrangement of the cyclometalated ligands. Electrochemical studies confirmed subtle perturbation of the IrIII/IV redox couple as a function of ligand variation. Luminescence studies showed the significant contribution of 3MLCT to the phosphorescent character with predictable and modestly tunable emission wavelengths between 618 and 636 nm. DFT studies provided approximate qualitative descriptions of the HOMO {located over the Ir(5d) center (11–42%) and the phenylquinoxaline ligand (54–87%)} and LUMO {located over the ancillary bipyridine ligands (ca. 93%)} energy levels of the five complexes, confirming significant MLCT character. TD-DFT calculations indicate that UV–vis absorption and subsequent emission has substantial MLCT character, mixed with LLCT. Predicted absorption and emission wavelengths are in good general agreement with the UV–vis and luminescence experiments.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Advanced Research Computing @ Cardiff (ARCCA) Chemistry
Subjects:	Q Science > QD Chemistry
Publisher:	American Chemical Society
ISSN:	0020-1669
Last Modified:	24 Oct 2022 09:58
URI:	https://orca.cardiff.ac.uk/id/eprint/42784

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