Luminescent Iridium–Terpyridine Complexes with Various Bis-Cyclometalated Ligands
A series of luminescent bis-cyclometalated iridium complexes with 2,2′:6′,2″-terpyridine (tpy), [Ir(<i>C^N</i>)<sub>2</sub>(tpy)]PF<sub>6</sub> (<i>C^N</i> = 2-phenylpyridinate (ppy) for <b>1</b>; benzo[h]quinolinate (bzq) for <b>2<...
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2025-01-01
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| author | Ko Ikeda Natsumi Yano Makoto Handa Yusuke Kataoka |
| author_facet | Ko Ikeda Natsumi Yano Makoto Handa Yusuke Kataoka |
| author_sort | Ko Ikeda |
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| description | A series of luminescent bis-cyclometalated iridium complexes with 2,2′:6′,2″-terpyridine (tpy), [Ir(<i>C^N</i>)<sub>2</sub>(tpy)]PF<sub>6</sub> (<i>C^N</i> = 2-phenylpyridinate (ppy) for <b>1</b>; benzo[h]quinolinate (bzq) for <b>2</b>; 1-phenylisoquinolinate (piq) for <b>3</b>; and 2-phenylbenzothiazolate (pbt) for <b>4</b>), have been synthesized and structurally characterized. Single-crystal X-ray diffraction analyses reveal that the tpy ligands of <b>1</b>–<b>4</b> are coordinated to the iridium center in a bidentate fashion, and the uncoordinated pendant pyridine rings in the tpy ligands of <b>1</b>–<b>4</b> form intramolecular π-π stacking interactions with a phenyl moiety of <i>C^N</i> ligands. In addition, the pendant pyridine ring in the tpy ligand of <b>1</b> forms an intramolecular hydrogen bonding interaction, unlike in <b>2</b>–<b>4</b>. Of interest, the photophysical properties of <b>1</b>–<b>4</b> are strongly influenced by the <i>C^N</i> ligands; <b>1</b> shows a luminescence band at 572 nm, with a short lifetime (τ) value of 80 nsec and a lower absolute luminescence quantum yield (Φ) of 3.72%, whereas <b>3</b> exhibits an intense luminescence band at 588 nm with a long τ value of 1965 nsec and a moderate Φ value of 9.57%. The density functional theory calculations revealed that the luminescence originates from the triplet metal–ligand to ligand charge transfer (<sup>3</sup>MLL′CT) excited state. |
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| institution | Kabale University |
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| language | English |
| publishDate | 2025-01-01 |
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| series | Molecules |
| spelling | doaj-art-87f796d17f78494b8f2bccf857be261f2025-01-10T13:19:10ZengMDPI AGMolecules1420-30492025-01-0130119310.3390/molecules30010193Luminescent Iridium–Terpyridine Complexes with Various Bis-Cyclometalated LigandsKo Ikeda0Natsumi Yano1Makoto Handa2Yusuke Kataoka3Department of Chemistry, Graduate School of Natural Science and Technology, Shimane University, 1060, Nishikawatsu, Matsue 690-8504, Shimane, JapanDepartment of Chemistry, Graduate School of Natural Science and Technology, Shimane University, 1060, Nishikawatsu, Matsue 690-8504, Shimane, JapanDepartment of Chemistry, Graduate School of Natural Science and Technology, Shimane University, 1060, Nishikawatsu, Matsue 690-8504, Shimane, JapanDepartment of Chemistry, Graduate School of Natural Science and Technology, Shimane University, 1060, Nishikawatsu, Matsue 690-8504, Shimane, JapanA series of luminescent bis-cyclometalated iridium complexes with 2,2′:6′,2″-terpyridine (tpy), [Ir(<i>C^N</i>)<sub>2</sub>(tpy)]PF<sub>6</sub> (<i>C^N</i> = 2-phenylpyridinate (ppy) for <b>1</b>; benzo[h]quinolinate (bzq) for <b>2</b>; 1-phenylisoquinolinate (piq) for <b>3</b>; and 2-phenylbenzothiazolate (pbt) for <b>4</b>), have been synthesized and structurally characterized. Single-crystal X-ray diffraction analyses reveal that the tpy ligands of <b>1</b>–<b>4</b> are coordinated to the iridium center in a bidentate fashion, and the uncoordinated pendant pyridine rings in the tpy ligands of <b>1</b>–<b>4</b> form intramolecular π-π stacking interactions with a phenyl moiety of <i>C^N</i> ligands. In addition, the pendant pyridine ring in the tpy ligand of <b>1</b> forms an intramolecular hydrogen bonding interaction, unlike in <b>2</b>–<b>4</b>. Of interest, the photophysical properties of <b>1</b>–<b>4</b> are strongly influenced by the <i>C^N</i> ligands; <b>1</b> shows a luminescence band at 572 nm, with a short lifetime (τ) value of 80 nsec and a lower absolute luminescence quantum yield (Φ) of 3.72%, whereas <b>3</b> exhibits an intense luminescence band at 588 nm with a long τ value of 1965 nsec and a moderate Φ value of 9.57%. The density functional theory calculations revealed that the luminescence originates from the triplet metal–ligand to ligand charge transfer (<sup>3</sup>MLL′CT) excited state.https://www.mdpi.com/1420-3049/30/1/193cyclometalated iridium complexesluminescent propertiescrystal structuresphotophysical propertiesterpyridine ligandssupramolecular interactions |
| spellingShingle | Ko Ikeda Natsumi Yano Makoto Handa Yusuke Kataoka Luminescent Iridium–Terpyridine Complexes with Various Bis-Cyclometalated Ligands Molecules cyclometalated iridium complexes luminescent properties crystal structures photophysical properties terpyridine ligands supramolecular interactions |
| title | Luminescent Iridium–Terpyridine Complexes with Various Bis-Cyclometalated Ligands |
| title_full | Luminescent Iridium–Terpyridine Complexes with Various Bis-Cyclometalated Ligands |
| title_fullStr | Luminescent Iridium–Terpyridine Complexes with Various Bis-Cyclometalated Ligands |
| title_full_unstemmed | Luminescent Iridium–Terpyridine Complexes with Various Bis-Cyclometalated Ligands |
| title_short | Luminescent Iridium–Terpyridine Complexes with Various Bis-Cyclometalated Ligands |
| title_sort | luminescent iridium terpyridine complexes with various bis cyclometalated ligands |
| topic | cyclometalated iridium complexes luminescent properties crystal structures photophysical properties terpyridine ligands supramolecular interactions |
| url | https://www.mdpi.com/1420-3049/30/1/193 |
| work_keys_str_mv | AT koikeda luminescentiridiumterpyridinecomplexeswithvariousbiscyclometalatedligands AT natsumiyano luminescentiridiumterpyridinecomplexeswithvariousbiscyclometalatedligands AT makotohanda luminescentiridiumterpyridinecomplexeswithvariousbiscyclometalatedligands AT yusukekataoka luminescentiridiumterpyridinecomplexeswithvariousbiscyclometalatedligands |