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Mizuno A, Matsuoka R, Mibu T, Kusamoto T. Luminescent Radicals. Chem Rev 2024; 124:1034-1121. [PMID: 38230673 DOI: 10.1021/acs.chemrev.3c00613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
Organic radicals are attracting increasing interest as a new class of molecular emitters. They demonstrate electronic excitation and relaxation dynamics based on their doublet or higher multiplet spin states, which are different from those based on singlet-triplet manifolds of conventional closed-shell molecules. Recent studies have disclosed luminescence properties and excited state dynamics unique to radicals, such as highly efficient electron-photon conversion in OLEDs, NIR emission, magnetoluminescence, an absence of heavy atom effect, and spin-dependent and spin-selective dynamics. These are difficult or sometimes impossible to achieve with closed-shell luminophores. This review focuses on luminescent organic radicals as an emerging photofunctional molecular system, and introduces the material developments, fundamental properties including luminescence, and photofunctions. Materials covered in this review range from monoradicals, radical oligomers, and radical polymers to metal complexes with radical ligands demonstrating radical-involved emission. In addition to stable radicals, transiently formed radicals generated in situ by external stimuli are introduced. This review shows that luminescent organic radicals have great potential to expand the chemical and spin spaces of luminescent molecular materials and thus broaden their applicability to photofunctional systems.
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Affiliation(s)
- Asato Mizuno
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
| | - Ryota Matsuoka
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Shonan Village, HayamaKanagawa 240-0193, Japan
| | - Takuto Mibu
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
| | - Tetsuro Kusamoto
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Shonan Village, HayamaKanagawa 240-0193, Japan
- JST-PRESTO, 4-1-8, Honcho, Kawaguchi, Saitama 332-0012, Japan
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
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2
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Shi J, Xu W, Yu H, Wang X, Jin F, Zhang Q, Zhang H, Peng Q, Abdurahman A, Wang M. A Highly Luminescent Metallo-Supramolecular Radical Cage. J Am Chem Soc 2023; 145:24081-24088. [PMID: 37796113 DOI: 10.1021/jacs.3c07477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/06/2023]
Abstract
Luminescent metal-radicals have recently received increasing attention due to their unique properties and promising applications in materials science. However, the luminescence of metal-radicals tends to be quenched after formation of metallo-complexes. It is challenging to construct metal-radicals with highly luminescent properties. Herein, we report a highly luminescent metallo-supramolecular radical cage (LMRC) constructed by the assembly of a tritopic terpyridinyl ligand RL with tris(2,4,6-trichlorophenyl)methyl (TTM) radical and Zn2+. Electrospray ionization-mass spectrometry (ESI-MS), traveling-wave ion mobility-mass spectrometry (TWIM-MS), X-ray crystallography, electron paramagnetic resonance (EPR) spectroscopy, and superconducting quantum interference device (SQUID) confirm the formation of a prism-like supramolecular radical cage. LMRC exhibits a remarkable photoluminescence quantum yield (PLQY) of 65%, which is 5 times that of RL; meanwhile, LMRC also shows high photostability. Notably, significant magnetoluminescence can be observed for the high-concentration LMRC (15 wt % doped in PMMA film); however, the magnetoluminescence of 0.1 wt % doped LMRC film vanishes, revealing negligible spin-spin interactions between two radical centers in LMRC.
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Affiliation(s)
- Junjuan Shi
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, Jilin 130012, China
| | - Wei Xu
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, Jilin 130012, China
| | - Hao Yu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, Jilin 130012, China
| | - Xing Wang
- Key Laboratory of Flexible Electronics (KLOFE), Institute of Advanced Materials (IAM) & School of Flexible Electronics (Future Technologies), Nanjing Tech University (Nanjing Tech), Nanjing, Jiangsu 211816, China
| | - Feng Jin
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Qingming Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Houyu Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, Jilin 130012, China
| | - Qiming Peng
- Key Laboratory of Flexible Electronics (KLOFE), Institute of Advanced Materials (IAM) & School of Flexible Electronics (Future Technologies), Nanjing Tech University (Nanjing Tech), Nanjing, Jiangsu 211816, China
| | - Alim Abdurahman
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Changchun, Jilin 130012, China
| | - Ming Wang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, Jilin 130012, China
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3
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Lu C, Cho E, Cui Z, Gao Y, Cao W, Brédas JL, Coropceanu V, Li F. Towards Efficient and Stable Donor-Acceptor Luminescent Radicals. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2208190. [PMID: 36417767 DOI: 10.1002/adma.202208190] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 11/01/2022] [Indexed: 06/16/2023]
Abstract
In contrast to closed-shell luminescent molecules, the electronic ground state and lowest excited state in organic luminescent radicals are both spin doublet, which results in spin-allowed radiative transitions. Most reported luminescent radicals with high photoluminescent quantum efficiency (PLQE) have a donor-acceptor (D-A•) chemical structure where an electron-donating group is covalently attached to an electron-withdrawing radical core (A•). Understanding the main factors that define the efficiency and stability of D-A• type luminescent radicals remains challenging. Here, we designed and synthesized a series of tri(2,4,6-trichlorophenyl)methyl (TTM) radical derivatives with donor substituents varying by their extent of conjugation and their number of imine-type nitrogen atoms. The experimental results suggest that the luminescence efficiency and stability of the radicals are proportional to the degree of conjugation but inversely proportional to the number of imine nitrogen atoms in the substituents. These experimental trends are very well reproduced by density functional theory calculations. The theoretical results indicate that both the luminescence efficiency and radical stability are related to the energy difference between the charge transfer (CT) and local-excitation (LE) states, which decreases as either the number of imine nitrogen atoms in the substituent increases or its conjugation length decreases.
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Affiliation(s)
- Chen Lu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Eunkyung Cho
- Department of Chemistry and Biochemistry, University of Arizona College of Science, Tucson, AZ, 85721-0088, USA
| | - Zhiyuan Cui
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Yuhang Gao
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Wenjuan Cao
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Jean-Luc Brédas
- Department of Chemistry and Biochemistry, University of Arizona College of Science, Tucson, AZ, 85721-0088, USA
| | - Veaceslav Coropceanu
- Department of Chemistry and Biochemistry, University of Arizona College of Science, Tucson, AZ, 85721-0088, USA
| | - Feng Li
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
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4
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Liu X, Wu M, Zeng R, Li G, Li Q, Li F, Yuan A, Shi C. Iridium(III) Complex Radical and Corresponding Ligand Radical Functionalized by a Tris(2,4,6-trichlorophenyl)methyl Unit: Synthesis, Structure, and Photophysical Properties. Inorg Chem 2022; 61:20942-20948. [PMID: 36520067 DOI: 10.1021/acs.inorgchem.2c03394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Organic radical luminescent materials with doublet excited state character based on tris(2,4,6-trichlorophenyl)methyl (TTM) have attracted extensive attention in recent years. However, how they affect the phosphorescent iridium(III) complex characterized by the triplet excited state has not been studied yet. Herein, a new iridium(III) complex radical (Ir-TTM) and corresponding ligand radical (ppy-TTM) with a TTM unit have been designed and synthesized, and their radical properties were confirmed by the single crystal structure and EPR spectra. Notably, the ligand radical ppy-TTM shows an efficient red light emission, whereas the iridium complex radical Ir-TTM emits no light, which resulted from the intramolecular quenching effect of the TTM radical unit on the iridium luminescence center. DFT calculations demonstrate that the lowest doublet (D1) excited state of ppy-TTM shows an intramolecular charge transfer character from the 2-phenylpyridine moieties to the TTM unit, whereas the D1 of Ir-TTM exhibits a significant charge transfer character from the iridium luminescence center moieties to the TTM unit, which further explains the luminescence quenching mechanism of the phosphorescent iridium complex radical.
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Affiliation(s)
- Xinyu Liu
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, P. R. China
| | - Meng Wu
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, P. R. China
| | - Ruoqi Zeng
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, P. R. China
| | - Gang Li
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, P. R. China
| | - Qiuxia Li
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, P. R. China
| | - Feiyang Li
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, P. R. China
| | - Aihua Yuan
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, P. R. China
| | - Chao Shi
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, P. R. China
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Structural and Magnetic Studies on Nickel(II) and Cobalt(II) Complexes with Polychlorinated Diphenyl(4-pyridyl)methyl Radical Ligands. Molecules 2021; 26:molecules26185596. [PMID: 34577066 PMCID: PMC8469047 DOI: 10.3390/molecules26185596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/09/2021] [Accepted: 09/10/2021] [Indexed: 11/26/2022] Open
Abstract
New magnetic metal complexes with organic radical ligands, [M(hfac)2(PyBTM)2] (M = NiII, CoII; hfac = hexafluoroacetylacetonato, PyBTM = (3,5-dichloro-4-pyridyl)bis(2,4,6-trichlorophenyl)methyl radical), were prepared and their crystal structures, magnetic properties, and electronic structures were investigated. Metal ions in [M(hfac)2(PyBTM)2] constructed distorted octahedral coordination geometry, where the two PyBTM molecules ligated in the trans configuration. Magnetic investigation using a SQUID magnetometer revealed that χT increased with decreasing temperature from 300 K in the two complexes, indicating an efficient intramolecular ferromagnetic exchange interaction taking place between the spins on PyBTM and M with J/kB of 21.8 K and 11.8 K for [NiII(hfac)2(PyBTM)2] and [CoII(hfac)2(PyBTM)2]. The intramolecular ferromagnetic couplings in the two complexes could be explained by density functional theory calculations, and would be attributed to a nearly orthogonal relationship between the spin orbitals on PyBTM and the metal ions. These results demonstrate that pyridyl-containing triarylmethyl radicals are key building blocks for magnetic molecular materials with controllable/predictable magnetic interactions.
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Kusamoto T, Kimura S. Photostable Luminescent Triarylmethyl Radicals and Their Metal Complexes: Photofunctions Unique to Open-shell Electronic States. CHEM LETT 2021. [DOI: 10.1246/cl.210201] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Tetsuro Kusamoto
- Institute for Molecular Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Shonan Village, Hayama, Kanagawa 240-0193, Japan
- JST-PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Shun Kimura
- Institute for Molecular Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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8
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Kimura S, Uejima M, Ota W, Sato T, Kusaka S, Matsuda R, Nishihara H, Kusamoto T. An Open-shell, Luminescent, Two-Dimensional Coordination Polymer with a Honeycomb Lattice and Triangular Organic Radical. J Am Chem Soc 2021; 143:4329-4338. [PMID: 33721501 DOI: 10.1021/jacs.0c13310] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The use of organic radicals as building blocks is an effective approach to the production of open-shell coordination polymers (CPs). Two-dimensional (2D) CPs with honeycomb spin-lattices have attracted attention because of the unique electronic structures and physical properties afforded by their structural topology. However, radical-based CPs with honeycomb spin-lattices tend to have low chemical stability or poor crystallinity, and thus novel systems with high crystallinity and persistence are in strong demand. In this study, a novel triangular organic radical possessing three pyridyl groups, tris(3,5-dichloro-4-pyridyl)methyl radical (trisPyM) was prepared. It exhibits luminescence, high photostability, and a coordination ability, allowing formation of defined and persistent 2D CPs. Optical measurements confirmed the luminescence of trisPyM both in solution and in the solid state, with emission wavelengths, λem, of 665 and 700 nm, respectively. trisPyM exhibits better chemical stability under photoirradiation than other luminescent radicals: the half-life of trisPyM in CH2Cl2 was 10 000 times that of the tris(2,4,6-trichlorophenyl)methyl radical (TTM), a conventional luminescent radical. Complexation between trisPyM and ZnII(hfac)2 yielded a single crystal of a 2D CP trisZn, possessing a honeycomb lattice with graphene-like spin topology. The coordination structure of trisZn is stable under evacuation at 60 °C. Moreover, trisZn exhibits luminescence at 79 K, with λem = 695 nm, and is a rare example of a luminescent material among 2D radical-based CPs. Our results indicate that trisPyM may be a promising building block in the construction of a new class of 2D honeycomb CPs with novel properties, including luminescence.
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Affiliation(s)
- Shun Kimura
- Institute for Molecular Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan.,Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Motoyuki Uejima
- MOLFEX, Inc., Takano-Nishibiraki-cho 34-4, Sakyo-ku, Kyoto 606-8103, Japan
| | - Wataru Ota
- Fukui Institute for Fundamental Chemistry, Kyoto University, Takano-Nishibiraki-cho 34-4, Sakyo-ku, Kyoto 606-8103, Japan.,Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8246, Japan
| | - Tohru Sato
- Fukui Institute for Fundamental Chemistry, Kyoto University, Takano-Nishibiraki-cho 34-4, Sakyo-ku, Kyoto 606-8103, Japan.,Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8246, Japan.,Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, Nishikyo-ku, Kyoto 615-8245, Japan
| | - Shinpei Kusaka
- Department of Chemistry and Biotechnology, School of Engineering, Nagoya University, Chikusa-ku, Nagoya, Aichi 464-8603, Japan
| | - Ryotaro Matsuda
- Department of Chemistry and Biotechnology, School of Engineering, Nagoya University, Chikusa-ku, Nagoya, Aichi 464-8603, Japan
| | - Hiroshi Nishihara
- Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.,Research Center for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Tetsuro Kusamoto
- Institute for Molecular Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan.,SOKENDAI (The Graduate University for Advanced Studies), Shonan Village, Hayama, 240-0193, Kanagawa Japan.,JST-PRESTO, 4-1-8, Honcho, Kawaguchi, Saitama 332-0012, Japan
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9
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Kimura S, Kimura S, Nishihara H, Kusamoto T. Excimer emission and magnetoluminescence of radical-based zinc(ii) complexes doped in host crystals. Chem Commun (Camb) 2020; 56:11195-11198. [DOI: 10.1039/d0cc04830e] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A ZnIIcomplex with luminescent organic radical ligands doped into host molecular crystals showed an excimer emission and its luminescent behavior was significantly modulated by an external magnetic field.
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Affiliation(s)
- Shun Kimura
- Institute for Molecular Science
- Okazaki
- Japan
- Department of Chemistry, Graduate School of Science, The University of Tokyo
- Tokyo
| | - Shojiro Kimura
- Institute for Materials Research, Tohoku University
- Sendai
- Japan
| | - Hiroshi Nishihara
- Department of Chemistry, Graduate School of Science, The University of Tokyo
- Tokyo
- Japan
- Research Center for Science and Technology, Tokyo University of Science
- Chiba 278-8510
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10
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Affiliation(s)
- Kenichi Kato
- Department of ChemistryGraduate School of ScienceKyoto University Oiwake-cho, Kitashirakawa, Sakyo-ku Kyoto 606-8502 Japan
| | - Atsuhiro Osuka
- Department of ChemistryGraduate School of ScienceKyoto University Oiwake-cho, Kitashirakawa, Sakyo-ku Kyoto 606-8502 Japan
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11
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Kato K, Osuka A. Platforms for Stable Carbon‐Centered Radicals. Angew Chem Int Ed Engl 2019; 58:8978-8986. [DOI: 10.1002/anie.201900307] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Indexed: 11/12/2022]
Affiliation(s)
- Kenichi Kato
- Department of ChemistryGraduate School of ScienceKyoto University Oiwake-cho, Kitashirakawa, Sakyo-ku Kyoto 606-8502 Japan
| | - Atsuhiro Osuka
- Department of ChemistryGraduate School of ScienceKyoto University Oiwake-cho, Kitashirakawa, Sakyo-ku Kyoto 606-8502 Japan
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12
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Gautam R, Petritis SJ, Astashkin AV, Tomat E. Paramagnetism and Fluorescence of Zinc(II) Tripyrrindione: A Luminescent Radical Based on a Redox-Active Biopyrrin. Inorg Chem 2018; 57:15240-15246. [PMID: 30418755 DOI: 10.1021/acs.inorgchem.8b02532] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ability of bilins and other biopyrrins to form fluorescent zinc complexes has been known for more than a century; however, the exact identity of the emissive species remains uncertain in many cases. Herein, we characterize the hitherto elusive zinc complex of tripyrrin-1,14-dione, an analogue of several orange urinary pigments. As previously observed for its Pd(II), Cu(II), and Ni(II) complexes, tripyrrindione binds Zn(II) as a dianionic radical and forms a paramagnetic complex carrying an unpaired electron on the ligand π-system. This species is stable at room temperature and undergoes quasi-reversible ligand-based redox chemistry. Although the complex is isolated as a coordination dimer in the solid state, optical absorption and electron paramagnetic resonance spectroscopic studies indicate that the monomer is prevalent in a tetrahydrofuran solution. The paramagnetic Zn(II) tripyrrindione complex is brightly fluorescent (λabs = 599 nm, λem = 644 nm, ΦF = 0.23 in THF), and its study provides a molecular basis for the observation, made over several decades since the 1930s, of fluorescent behavior of tripyrrindione pigments in the presence of zinc salts. The zinc-bound tripyrrindione radical is thus a new addition to the limited number of stable radicals that are fluorescent at room temperature.
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Affiliation(s)
- Ritika Gautam
- Department of Chemistry and Biochemistry , The University of Arizona , Tucson , Arizona 85721 , United States
| | - Steven J Petritis
- Department of Chemistry and Biochemistry , The University of Arizona , Tucson , Arizona 85721 , United States
| | - Andrei V Astashkin
- Department of Chemistry and Biochemistry , The University of Arizona , Tucson , Arizona 85721 , United States
| | - Elisa Tomat
- Department of Chemistry and Biochemistry , The University of Arizona , Tucson , Arizona 85721 , United States
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13
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Kimura S, Tanushi A, Kusamoto T, Kochi S, Sato T, Nishihara H. A luminescent organic radical with two pyridyl groups: high photostability and dual stimuli-responsive properties, with theoretical analyses of photophysical processes. Chem Sci 2018; 9:1996-2007. [PMID: 29675247 PMCID: PMC5892406 DOI: 10.1039/c7sc04034b] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 01/09/2018] [Indexed: 11/30/2022] Open
Abstract
Increased photostability and a theoretical estimation of the radiative and non-radiative rates of luminescent organic radicals were achieved.
Luminescent monoradicals are expected to show unique properties based on their doublet state, where establishing a method to improve their photostability is an important issue for expanding their photofunctionality. We synthesized a highly photostable luminescent organic radical, the bis(3,5-dichloro-4-pyridyl)(2,4,6-trichlorophenyl)methyl radical (bisPyTM), containing two pyridyl groups on a tris(2,4,6-trichlorophenyl)methyl radical (TTM) skeleton. bisPyTM in dichloromethane exhibited fluorescence with an emission peak wavelength, λem, of 650 nm. We visually detected an emission (λem = 712 nm) from crystalline bisPyTM at 77 K, which is the first example of definite solid-state emission in a radical. Introducing the two nitrogen atoms into the TTM skeleton was shown to lower the energies of the frontier orbitals. The oscillator strength, f, of the electronic transition between the lowest excited state and the ground state, and the off-diagonal vibronic coupling constants (VCCs) were calculated theoretically for bisPyTM and the (3,5-dichloro-4-pyridyl)bis(2,4,6-trichlorophenyl)methyl radical (PyBTM). The calculated PyBTM to bisPyTM ratios for f or VCC agreed well with experimental radiative and non-radiative rate constants (kr and knr) ratios, respectively. This study shows that scaled kr and knr can be estimated and compared in this class of radicals using theoretical calculations, greatly advancing the prediction and design of their photofunctionality. The half-life of bisPyTM upon continuous UV light irradiation in dichloromethane was 47 or 3000 times longer those that of PyBTM (which contains one pyridyl group) and TTM (which has no pyridyl rings), respectively. The electrochemical and luminescent properties of bisPyTM were modulated in two stages using protons or B(C6F5)3.
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Affiliation(s)
- Shun Kimura
- Department of Chemistry , Graduate School of Science , The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku , Tokyo 113-0033 , Japan . ;
| | - Akira Tanushi
- Department of Chemistry , Graduate School of Science , The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku , Tokyo 113-0033 , Japan . ;
| | - Tetsuro Kusamoto
- Department of Chemistry , Graduate School of Science , The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku , Tokyo 113-0033 , Japan . ;
| | - Shuntaro Kochi
- Department of Molecular Engineering , Graduate School of Engineering , Kyoto University , Nishikyo-ku , Kyoto , 615-8510 , Japan
| | - Tohru Sato
- Department of Molecular Engineering , Graduate School of Engineering , Kyoto University , Nishikyo-ku , Kyoto , 615-8510 , Japan.,Unit of Elements Strategy Initiative for Catalysts & Batteries , Kyoto University , Nishikyo-ku , Kyoto , 615-8510 , Japan
| | - Hiroshi Nishihara
- Department of Chemistry , Graduate School of Science , The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku , Tokyo 113-0033 , Japan . ;
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Hattori Y, Kimura S, Kusamoto T, Maeda H, Nishihara H. Cation-responsive turn-on fluorescence and absence of heavy atom effects of pyridyl-substituted triarylmethyl radicals. Chem Commun (Camb) 2018; 54:615-618. [DOI: 10.1039/c7cc08568k] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pyridyl-substituted triarylmethyl radicals showed cation-responsive turn-on fluorescence and did not suffer from quenching by internal and external heavy atom effects.
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Affiliation(s)
- Yohei Hattori
- Department of Chemistry
- School of Science
- The University of Tokyo
- Tokyo
- Japan
| | - Shun Kimura
- Department of Chemistry
- School of Science
- The University of Tokyo
- Tokyo
- Japan
| | - Tetsuro Kusamoto
- Department of Chemistry
- School of Science
- The University of Tokyo
- Tokyo
- Japan
| | - Hiroaki Maeda
- Department of Chemistry
- School of Science
- The University of Tokyo
- Tokyo
- Japan
| | - Hiroshi Nishihara
- Department of Chemistry
- School of Science
- The University of Tokyo
- Tokyo
- Japan
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15
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Feuerstein TJ, Poß M, Seifert TP, Bestgen S, Feldmann C, Roesky PW. A highly luminescent octanuclear gold(i) carbide cluster. Chem Commun (Camb) 2017; 53:9012-9015. [PMID: 28787044 DOI: 10.1039/c7cc04171c] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
An octanuclear gold(i) carbide bridged amidinate cluster [Au8{μ3-(η1:η2-CC)}2(Me3SiCCC(NDipp)2)4(tht)2], which is the first gold(i) complex with a μ3-η1:η2carbide coordination, has been synthesized. The cluster shows intense luminescence with notable high quantum yields both in the solid state and in solution.
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Affiliation(s)
- Thomas J. Feuerstein
- Institute of Inorganic Chemistry
- Karlsruhe Institute of Technology
- 76131 Karlsruhe
- Germany
| | - Marieke Poß
- Institute of Inorganic Chemistry
- Karlsruhe Institute of Technology
- 76131 Karlsruhe
- Germany
| | - Tim P. Seifert
- Institute of Inorganic Chemistry
- Karlsruhe Institute of Technology
- 76131 Karlsruhe
- Germany
| | - Sebastian Bestgen
- Institute of Inorganic Chemistry
- Karlsruhe Institute of Technology
- 76131 Karlsruhe
- Germany
| | - Claus Feldmann
- Institute of Inorganic Chemistry
- Karlsruhe Institute of Technology
- 76131 Karlsruhe
- Germany
| | - Peter W. Roesky
- Institute of Inorganic Chemistry
- Karlsruhe Institute of Technology
- 76131 Karlsruhe
- Germany
| |
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