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Zhang F, Zhang Z, Zhao Y, Du C, Li Y, Gao J, Ren X, Ma T, Li B, Bu Y. Redox-Regulated Magnetic Conversions between Ferro- and Antiferromagnetism in Organic Nitroxide Diradicals. Molecules 2023; 28:6232. [PMID: 37687060 PMCID: PMC10488413 DOI: 10.3390/molecules28176232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 08/07/2023] [Accepted: 08/21/2023] [Indexed: 09/10/2023] Open
Abstract
Redox-induced magnetic transformation in organic diradicals is an appealing phenomenon. In this study, we theoretically designed twelve couples of diradicals in which two nitroxide (NO) radical groups are connected to the redox-active couplers including p-benzoquinonyl, 1,4-naphthoquinyl, 9,10-anthraquinonyl, naphthacene-5,12-dione, pentacene-6,13-dione, hexacene-6,15-dione, pyrazinyl, quinoxalinyl, phenazinyl, 5,12-diazanaphthacene, 6,13-diazapentacene, and 6,15-diazahexacene. As evidenced at both the B3LYP and M06-2X levels of theory, the calculations reveal that the magnetic reversal can take place from ferromagnetism to antiferromagnetism, or vice versa, by means of redox method in these designed organic magnetic molecules. It was observed that p-benzoquinonyl, 1,4-naphthoquinyl, 9,10-anthraquinonyl, naphthacene-5,12-dione, pentacene-6,13-dione, and hexacene-6,15-dione-bridged NO diradicals produce antiferromagnetism while their dihydrogenated counterparts exhibit ferromagnetism. Similarly, pyrazinyl, quinoxalinyl, phenazinyl, 5,12-diazanaphthacene, 6,13-diazapentacene, and 6,15-diazahexacene-bridged NO diradicals present ferromagnetism while their dihydrogenated counterparts show antiferromagnetism. The differences in the magnetic behaviors and magnetic magnitudes of each of the twelve couples of diradicals could be attributed to their distinctly different spin-interacting pathways. It was found that the nature of the coupler and the length of the coupling path are important factors in controlling the magnitude of the magnetic exchange coupling constant J. Specifically, smaller HOMO-LUMO (HOMO: highest occupied molecular orbital, LUMO: lowest unoccupied molecular orbital) gaps of the couplers and shorter coupler lengths, as well as shorter linking bond lengths, can attain stronger magnetic interactions. In addition, a diradical with an extensively π-conjugated structure is beneficial to spin transport and can effectively promote magnetic coupling, yielding a large |J| accordingly. That is, a larger spin polarization can give rise to a stronger magnetic interaction. The sign of J for these studied diradicals can be predicted from the spin alternation rule, the shape of the singly occupied molecular orbitals (SOMOs), and the SOMO-SOMO energy gaps of the triplet state. This study paves the way for the rational design of magnetic molecular switches.
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Affiliation(s)
- Fengying Zhang
- Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030619, China; (C.D.); (Y.L.); (J.G.); (X.R.); (T.M.); (B.L.)
- Shanxi Province Collaborative Innovation Center for Light Materials Modification and Application, Jinzhong 030619, China
| | - Zijun Zhang
- Department of Chemistry and Chemical Engineering, Jinzhong University, Jinzhong 030619, China;
| | - Yali Zhao
- Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030619, China; (C.D.); (Y.L.); (J.G.); (X.R.); (T.M.); (B.L.)
- Shanxi Province Collaborative Innovation Center for Light Materials Modification and Application, Jinzhong 030619, China
| | - Chao Du
- Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030619, China; (C.D.); (Y.L.); (J.G.); (X.R.); (T.M.); (B.L.)
- Shanxi Province Collaborative Innovation Center for Light Materials Modification and Application, Jinzhong 030619, China
| | - Yong Li
- Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030619, China; (C.D.); (Y.L.); (J.G.); (X.R.); (T.M.); (B.L.)
- Shanxi Province Collaborative Innovation Center for Light Materials Modification and Application, Jinzhong 030619, China
| | - Jiaqi Gao
- Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030619, China; (C.D.); (Y.L.); (J.G.); (X.R.); (T.M.); (B.L.)
- Shanxi Province Collaborative Innovation Center for Light Materials Modification and Application, Jinzhong 030619, China
| | - Xiaobo Ren
- Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030619, China; (C.D.); (Y.L.); (J.G.); (X.R.); (T.M.); (B.L.)
- Shanxi Province Collaborative Innovation Center for Light Materials Modification and Application, Jinzhong 030619, China
| | - Teng Ma
- Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030619, China; (C.D.); (Y.L.); (J.G.); (X.R.); (T.M.); (B.L.)
- Shanxi Province Collaborative Innovation Center for Light Materials Modification and Application, Jinzhong 030619, China
| | - Boqiong Li
- Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030619, China; (C.D.); (Y.L.); (J.G.); (X.R.); (T.M.); (B.L.)
- Shanxi Province Collaborative Innovation Center for Light Materials Modification and Application, Jinzhong 030619, China
| | - Yuxiang Bu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China;
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