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Osawa M, Aino MA, Nagakura T, Hoshino M, Tanaka Y, Akita M. Near-unity thermally activated delayed fluorescence efficiency in three- and four-coordinate Au(i) complexes with diphosphine ligands. Dalton Trans 2018; 47:8229-8239. [PMID: 29756141 DOI: 10.1039/c8dt01097h] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The synthesis and photoluminescence properties of three-coordinate Au(i) complexes with rigid diphosphine ligands LMe {1,2-bis[bis(2-methylphenyl)phosphino]benzene}, LEt {1,2-bis[bis(2-ethylphenyl)phosphino]benzene}, and LiPr {1,2-bis[bis(2-isopropylphenyl)phosphino]benzene} are investigated. The LMe and LEt ligands afford two types of complexes: dinuclear complexes [μ-LMe(AuCl)2] (1d) and [μ-LEt(AuCl)2] (2d) with an Au(i)-Au(i) bond and mononuclear three-coordinate Au(i) complexes LMeAuCl (1) and LEtAuCl (2). On the other hand, the bulkiest ligand, LiPr, affords three-coordinate Au(i) complexes, LiPrAuCl (3) and LiPrAuI (4), but no dinuclear complexes. X-ray analysis suggests that both 3 and 4 possess a highly distorted trigonal planar geometry. Moreover, luminescence data reveal that at room temperature, 3 and 4 exhibit yellow-green thermally activated delayed fluorescence in the crystalline state with maximum emission wavelengths at 558 and 549 nm, respectively. The emission yields are close to unity. Quantum chemical calculations suggest that the emission of 4 originates from the (σ + X) → π* excited state that possesses strong intraligand charge-transfer character. The luminescent properties of four-coordinate Au(i) complex (5) possessing a tetrahedral geometry are discussed on the basis of the emission spectra and decay times measured in a temperature range of 309-77 K.
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Affiliation(s)
- Masahisa Osawa
- Department of Applied Chemistry, Nippon Institute of Technology, Gakuendai 4-1, Miyashiro-Machi, Saitama, 345-8501, Japan.
| | - Masa-Aki Aino
- Department of Applied Chemistry, Nippon Institute of Technology, Gakuendai 4-1, Miyashiro-Machi, Saitama, 345-8501, Japan.
| | - Takaki Nagakura
- Department of Applied Chemistry, Nippon Institute of Technology, Gakuendai 4-1, Miyashiro-Machi, Saitama, 345-8501, Japan.
| | - Mikio Hoshino
- Department of Applied Chemistry, Nippon Institute of Technology, Gakuendai 4-1, Miyashiro-Machi, Saitama, 345-8501, Japan.
| | - Yuya Tanaka
- Laboratory for Chemistry and Life Science Institute of Innovative Research, Tokyo Institute of Technology, R1-27, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
| | - Munetaka Akita
- Laboratory for Chemistry and Life Science Institute of Innovative Research, Tokyo Institute of Technology, R1-27, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
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