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Scattergood PA, Roberts J, Omar SAE, Elliott PIP. Observation of an Inversion in Photophysical Tuning in a Systematic Study of Luminescent Triazole-Based Osmium(II) Complexes. Inorg Chem 2019; 58:8607-8621. [PMID: 31180230 DOI: 10.1021/acs.inorgchem.9b00915] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In a systematic survey of luminescent bis(terdentate) osmium(II) complexes, a tipping point involving a reversal in photophysical tuning is observed whereby increasing stabilization of the ligand-based lowest unoccupied molecular orbital (LUMO) results in a blue shift in the optical absorption and emission bands. The complexes [Os(N^N'^N″)2]2+ [N^N'^N″ = 2,6-bis(1-phenyl-1,2,3-triazol-4-yl)pyridine (Os1), 2,6-bis(1-benzyl-1,2,3-triazol-4-yl)pyrazine (Os2), 6-(1-benzyl-1,2,3-triazol-4-yl)-2,2'-bipyridyl (Os3), 2-(pyrid-2-yl)-6-(1-benzyl-1,2,3-triazol-4-yl)pyrazine (Os4), 2-(pyrazin-2-yl)-6-(1-benzyl-1,2,3-triazol-4-yl)pyridine (Os5), and 6-(1-benzyl-1,2,3-triazol-4-yl)-2,2'-bipyrazinyl (Os6)] have been prepared and characterized, and all complexes display phosphorescence ranging from the orange to near-IR regions of the spectrum. Replacement of the central pyridine in the ligands of Os1 by the more π-accepting pyrazine in Os2 results in a 55 nm red shift in the triplet metal-to-ligand charge-transfer-based emission band, while a larger red shift of 107 nm is observed for the replacement of one of the triazole donors in the ligands of Os1 by a second pyridine ring in Os3 (λemmax = 702 nm). Interestingly, replacement of the central pyridine ring in the ligands of Os3 by pyrazine (Os4, λemmax = 702 nm) fails to result in a further red shift in the emission band. Reversal of the relative positions of the pyridine and pyrazine donors in Os5 (λemmax = 733 nm) compared to Os4 does indeed result in the expected red shift in the emission with respect to that for Os3 based on the increased π-acceptor character of the ligands present. However, an inversion in emission tuning is observed for Os6, in which the incorporation of a second pyrazine donor in the ligand architecture results in a blue shift in the optical absorption and emission maxima (λemmax = 710 nm). Electrochemical studies reveal that while incorporating pyrazine in the ligands indeed results in an expected anodic shift in the first reduction potential through stabilization of the ligand-based LUMO, there is also a concomitant anodic shift in the OsII/OsIII-based oxidation potential. This stabilization of the metal-based highest occupied molecular orbital (HOMO) thus nullifies the effect of stabilization of the LUMO in Os4 compared to Os3, resulting in these complexes having coincident emission maxima. For Os6, stabilization of the HOMO through the incorporation of two pyrazine donors in the ligand structure now exceeds stabilization of the LUMO, resulting in a larger HOMO-LUMO gap and a counterintuitive blue shift in the optical properties in comparison with those of Os5. While it is known that the replacement of ligands (e.g., replacing bipyridyl with bipyrazinyl) can result in a larger HOMO-LUMO energy gap through greater stabilization of the HOMO, these results importantly allow us to capture the tipping point at which this inversion in photophysical tuning occurs. This therefore enables us to explore the limits available in emission tuning with a relatively simple and minimalist ligand structure.
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Davidson R, Liang JH, Costa Milan D, Mao BW, Nichols RJ, Higgins SJ, Yufit DS, Beeby A, Low PJ. Synthesis, Electrochemistry, and Single-Molecule Conductance of Bimetallic 2,3,5,6-Tetra(pyridine-2-yl)pyrazine-Based Complexes. Inorg Chem 2015; 54:5487-94. [DOI: 10.1021/acs.inorgchem.5b00507] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ross Davidson
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
- State Key Laboratory of Physical Chemistry of Solid Surfaces and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Perth, Western Australia 6009, Australia
| | - Jing-Hong Liang
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
- State Key Laboratory of Physical Chemistry of Solid Surfaces and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Perth, Western Australia 6009, Australia
| | - David Costa Milan
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
- State Key Laboratory of Physical Chemistry of Solid Surfaces and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Perth, Western Australia 6009, Australia
| | - Bing-Wei Mao
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
- State Key Laboratory of Physical Chemistry of Solid Surfaces and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Perth, Western Australia 6009, Australia
| | - Richard J. Nichols
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
- State Key Laboratory of Physical Chemistry of Solid Surfaces and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Perth, Western Australia 6009, Australia
| | - Simon J. Higgins
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
- State Key Laboratory of Physical Chemistry of Solid Surfaces and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Perth, Western Australia 6009, Australia
| | - Dmitry S. Yufit
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
- State Key Laboratory of Physical Chemistry of Solid Surfaces and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Perth, Western Australia 6009, Australia
| | - Andrew Beeby
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
- State Key Laboratory of Physical Chemistry of Solid Surfaces and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Perth, Western Australia 6009, Australia
| | - Paul J. Low
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
- State Key Laboratory of Physical Chemistry of Solid Surfaces and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Perth, Western Australia 6009, Australia
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Nagashima T, Nakabayashi T, Suzuki T, Kanaizuka K, Ozawa H, Zhong YW, Masaoka S, Sakai K, Haga MA. Tuning of Metal–Metal Interactions in Mixed-Valence States of Cyclometalated Dinuclear Ruthenium and Osmium Complexes Bearing Tetrapyridylpyrazine or -benzene. Organometallics 2014. [DOI: 10.1021/om500142t] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Takumi Nagashima
- Department of Applied Chemistry, Faculty of
Science and Engineering, Chuo University, 1-13-27 Kasuga,
Bunkyo-ku, Tokyo 112-8551, Japan
| | - Takuya Nakabayashi
- Department of Applied Chemistry, Faculty of
Science and Engineering, Chuo University, 1-13-27 Kasuga,
Bunkyo-ku, Tokyo 112-8551, Japan
| | - Takashi Suzuki
- Department of Applied Chemistry, Faculty of
Science and Engineering, Chuo University, 1-13-27 Kasuga,
Bunkyo-ku, Tokyo 112-8551, Japan
| | - Katsuhiko Kanaizuka
- Department of Applied Chemistry, Faculty of
Science and Engineering, Chuo University, 1-13-27 Kasuga,
Bunkyo-ku, Tokyo 112-8551, Japan
| | - Hiroaki Ozawa
- Department of Applied Chemistry, Faculty of
Science and Engineering, Chuo University, 1-13-27 Kasuga,
Bunkyo-ku, Tokyo 112-8551, Japan
| | - Yu-Wu Zhong
- Beijing National Laboratory for
Molecular Sciences,
CAS Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Shigeyuki Masaoka
- Institute
for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Japan
| | - Ken Sakai
- Department of Chemistry, Faculty of Science, Kyushu University, Hakozaki
6-10-1, Higashi-ku, Fukuoka 812-8581, Japan
| | - Masa-aki Haga
- Department of Applied Chemistry, Faculty of
Science and Engineering, Chuo University, 1-13-27 Kasuga,
Bunkyo-ku, Tokyo 112-8551, Japan
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