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

Christine E. Welby, Luke Gilmartin, Ryan R. Marriott, Adam Zahid, Craig R. Rice, Elizabeth A. Gibson, Paul I.P. Elliott

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Abstract

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.

LanguageEnglish
Pages13527-13536
Number of pages10
JournalDalton Transactions
Volume42
Issue number37
DOIs
Publication statusPublished - 7 Oct 2013

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Iridium
Ligands
Triazoles
Excited states
Density functional theory
Electrons

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Welby, Christine E. ; Gilmartin, Luke ; Marriott, Ryan R. ; Zahid, Adam ; Rice, Craig R. ; Gibson, Elizabeth A. ; Elliott, Paul I.P. / Luminescent biscyclometalated arylpyridine iridium(iii) complexes with 4,4′-bi-1,2,3-triazolyl ancillary ligands. In: Dalton Transactions. 2013 ; Vol. 42, No. 37. pp. 13527-13536.
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title = "Luminescent biscyclometalated arylpyridine iridium(iii) complexes with 4,4′-bi-1,2,3-triazolyl ancillary ligands",
abstract = "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.",
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Luminescent biscyclometalated arylpyridine iridium(iii) complexes with 4,4′-bi-1,2,3-triazolyl ancillary ligands. / Welby, Christine E.; Gilmartin, Luke; Marriott, Ryan R.; Zahid, Adam; Rice, Craig R.; Gibson, Elizabeth A.; Elliott, Paul I.P.

In: Dalton Transactions, Vol. 42, No. 37, 07.10.2013, p. 13527-13536.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Luminescent biscyclometalated arylpyridine iridium(iii) complexes with 4,4′-bi-1,2,3-triazolyl ancillary ligands

AU - Welby, Christine E.

AU - Gilmartin, Luke

AU - Marriott, Ryan R.

AU - Zahid, Adam

AU - Rice, Craig R.

AU - Gibson, Elizabeth A.

AU - Elliott, Paul I.P.

PY - 2013/10/7

Y1 - 2013/10/7

N2 - 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.

AB - 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.

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U2 - 10.1039/c3dt51284c

DO - 10.1039/c3dt51284c

M3 - Article

VL - 42

SP - 13527

EP - 13536

JO - Dalton Transactions

T2 - Dalton Transactions

JF - Dalton Transactions

SN - 1477-9226

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