Issue 37, 2013

Luminescent biscyclometalated arylpyridine iridium(iii) complexes with 4,4′-bi-1,2,3-triazolyl ancillary ligands


The synthesis, characterization and photophysical investigation of complexes of the form [Ir(R-ppy)2(btz)]PF6 (1 to 3) are reported (btz = 1,1′-dibenzyl-4,4′-bi-1,2,3-triazolyl, R-ppy = 4-(pyrid-2-yl)benzaldehyde (1), 2-phenylpyridine (2) and 2-(2,4-difluorophenyl)pyridine (3)). Complexes 1, 2 and 3 are luminescent and exhibit structured emission bands with vibronic progressions at 532 & 568 nm (ϕ 0.28%), 476 & 508 nm (ϕ 0.82%) and 454 & 483 nm (ϕ 4.3%) respectively. The structuring of these emission bands is indicative of cyclometalated ligand centred emissive states and is further corroborated by the nearly identical emission spectra for 2 and 3 to previously reported analogous complexes with 4-(pyrid-2-yl)-1,2,3-triazole based ancillary ligands. Computational density functional theory calculations on these complexes show that the LUMOs of 2 and 3 are largely btz-centred but with some cyclometalated pyridine π* character. The LUMO of 1 on the other hand is localized primarily on the cyclometalated ligands. Spin population analysis of the lowest lying triplet excited states for these complexes indicate significant spin population over the iridium centres and the aryl and pyridyl moieties in these complexes with virtually no localization of unpaired electrons over the btz ancillary ligands. This is therefore in agreement with the assignment of the emissive state having largely cyclometalated 3LC character and being independent of the ancillary ligand.

Graphical abstract: Luminescent biscyclometalated arylpyridine iridium(iii) complexes with 4,4′-bi-1,2,3-triazolyl ancillary ligands

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Article information

Article type
16 May 2013
17 Jul 2013
First published
18 Jul 2013
This article is Open Access
Creative Commons BY license

Dalton Trans., 2013,42, 13527-13536

Luminescent biscyclometalated arylpyridine iridium(III) complexes with 4,4′-bi-1,2,3-triazolyl ancillary ligands

C. E. Welby, L. Gilmartin, R. R. Marriott, A. Zahid, C. R. Rice, E. A. Gibson and P. I. P. Elliott, Dalton Trans., 2013, 42, 13527 DOI: 10.1039/C3DT51284C

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