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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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Cui H, Hu ZB, Chen C, Ruan H, Fang Y, Zhang L, Zhao Y, Tan G, Song Y, Wang X. A high-spin diradical dianion and its bridged chemically switchable single-molecule magnet. Chem Sci 2021; 12:9998-10004. [PMID: 34377394 PMCID: PMC8317668 DOI: 10.1039/d1sc01932e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 06/21/2021] [Indexed: 11/21/2022] Open
Abstract
Triplet diradicals have attracted tremendous attention due to their promising application in organic spintronics, organic magnets and spin filters. However, very few examples of triplet diradicals with singlet–triplet energy gaps (ΔEST) over 0.59 kcal mol−1 (298 K) have been reported to date. In this work, we first proved that the dianion of 2,7-di-tert-butyl-pyrene-4,5,9,10-tetraone (2,7-tBu2-PTO) was a triplet ground state diradical in the magnesium complex 1 with a singlet–triplet energy gap ΔEST = 0.94 kcal mol−1 (473 K). This is a rare example of stable diradicals with singlet–triplet energy gaps exceeding the thermal energy at room temperature (298 K). Moreover, the iron analog 2 containing the 2,7-tBu2-PTO diradical dianion was isolated, which was the first single-molecule magnet bridged by a diradical dianion. When 2 was doubly reduced to the dianion salt 2K2, single-molecule magnetism was switched off, highlighting the importance of diradicals in single-molecule magnetism. We report a triplet diradical dianion in magnesium complex with ΔEST = 0.94 kcal mol−1 (473 K). Its iron analog is the first single-molecule magnet bridged by a diradical dianion, and the SMM property is switched off through two-electron reduction.![]()
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Affiliation(s)
- Haiyan Cui
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210023 China .,Jiangsu Key Laboratory of Pesticide Science, College of Sciences, Nanjing Agricultural University Nanjing 210095 China
| | - Zhao-Bo Hu
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210023 China
| | - Chao Chen
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210023 China
| | - Huapeng Ruan
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210023 China
| | - Yong Fang
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210023 China
| | - Li Zhang
- Center of Materials Science and Engineering, Guangxi University of Science and Technology Liuzhou 545006 China
| | - Yue Zhao
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210023 China
| | - Gengwen Tan
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University Suzhou 215123 China
| | - You Song
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210023 China
| | - Xinping Wang
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210023 China
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Olankitwanit A, Rajca S, Rajca A. Aza-m-Xylylene Diradical with Increased Steric Protection of the Aminyl Radicals. J Org Chem 2015; 80:5035-44. [DOI: 10.1021/acs.joc.5b00421] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Arnon Olankitwanit
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Suchada Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
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Affiliation(s)
- Nolan M. Gallagher
- Department
of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Arnon Olankitwanit
- Department
of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Andrzej Rajca
- Department
of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
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Olankitwanit A, Pink M, Rajca S, Rajca A. Synthesis of Aza-m-Xylylene Diradicals with Large Singlet–Triplet Energy Gap and Statistical Analyses of Their EPR Spectra. J Am Chem Soc 2014; 136:14277-88. [DOI: 10.1021/ja508119d] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Arnon Olankitwanit
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Maren Pink
- IUMSC, Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, United States
| | - Suchada Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
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Rajca A, Olankitwanit A, Rajca S. Triplet Ground State Derivative of Aza-m-xylylene Diradical with Large Singlet−Triplet Energy Gap. J Am Chem Soc 2011; 133:4750-3. [DOI: 10.1021/ja200708b] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Arnon Olankitwanit
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Suchada Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
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Neuhaus P, Grote D, Sander W. Matrix Isolation, Spectroscopic Characterization, and Photoisomerization of m-Xylylene. J Am Chem Soc 2008; 130:2993-3000. [DOI: 10.1021/ja073453d] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Patrik Neuhaus
- Lehrstuhl für Organische Chemie II der Ruhr-Universität, D-44780 Bochum, Germany
| | - Dirk Grote
- Lehrstuhl für Organische Chemie II der Ruhr-Universität, D-44780 Bochum, Germany
| | - Wolfram Sander
- Lehrstuhl für Organische Chemie II der Ruhr-Universität, D-44780 Bochum, Germany
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Abe M, Adam W, Minamoto T, Ino Y, Nojima M. Mechanism of an alcohol-trapping reaction in the direct and benzophenone-sensitized photodenitrogenation of a spiroepoxy-substituted azoalkane: solvent effects and stereochemical deuterium labeling. J Org Chem 2003; 68:1796-803. [PMID: 12608793 DOI: 10.1021/jo026873o] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The spin-state-dependent reactivity, singlet versus triplet, of the 2-spiroepoxy-1,3-cyclopentane-1,3-diyl DR2 has been assessed through alcohol-trapping reactions for which the effect of solvent acidity on the product distribution of the alcohol trapping products 2 versus 3 + 4 and stereochemical deuterium-labeling studies have been performed. The proposed mechanism for the solvent effect on the product ratio (2/3 + 4) reveals the importance of the hydrogen-bonded intermediates I1 and I2 in the trapping reactions; the stereochemical deuterium-labeling results clarify the dipole structure trapped by the alcohol. The dipoles DP1 and DP2, in which the configuration between the epoxide oxygen and the deuterium atoms is retained, are inferred for the direct photodenitrogenation reactions (singlet state), whereas for the benzophenone-sensitized photoreactions (triplet state), after ISC, the ring-opened dipole DP3 is implied as the intermediate that is trapped by the alcohol.
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Affiliation(s)
- Manabu Abe
- Department of Materials Chemistry & Frontier Research Center (HANDAI FRC), Graduate School of Engineering, Osaka University (HANDAI), Suita, 565-0871 Osaka, Japan.
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Miranda MA, Pérez-Prieto J, Font-Sanchis E, Scaiano JC. One- vs two-photon processes in the photochemistry of 1,n-dihaloalkanes. Acc Chem Res 2001; 34:717-26. [PMID: 11560471 DOI: 10.1021/ar000107r] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1,n-Dihaloalkanes can be photochemical precursors of n-haloalkyl and -allyl radicals and cations, which are generated via one-photon processes. Time-resolved techniques have provided considerable information on the structures and reactivity of these intermediates. Low-temperature matrix isolation, two-laser two-color, laser-drop, and laser-jet photolysis techniques are powerful tools to photolyze haloalkyl radicals and to generate carbenes or biradicals via two-photon processes.
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Affiliation(s)
- M A Miranda
- Instituto de Tecnología Química UPV-CSIC//Departamento de Química, Universidad Politécnica de Valencia, Camino de Vera s/n, 46071 Valencia, Spain.
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Fujiwara M, Yamasaki A, Mishima K, Toyomi K. A mechanism of photodissociation of diphenylmethane to a diphenylmethyl radical in solution. J Chem Phys 1998. [DOI: 10.1063/1.476688] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Rezende DDB, de Arruda Campos IP, Toscano VG, Catalani LH. Photolysis of a series of α-brominated ortho-xylenes in apolar solvents. ACTA ACUST UNITED AC 1995. [DOI: 10.1039/p29950001857] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Tukada H. 3-Ylomethylphenylnitrate a novel quartet species having doubly heterogeneous radical sites (N and C atom; S= 1 and 1/2 center) in a π-conjugated molecule. ACTA ACUST UNITED AC 1993. [DOI: 10.1039/c39930000302] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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