Abstract
Organic radicals display unique physical structures and could become next generation functional materials. However, design and synthesis of stable neutral radicals with a significant polyradical character has been an enormous challenge for chemists. In this work, we synthesized a series of stable 3,6-linked, kinetically blocked fluorenyl radical oligomers up to hexamer (FR-n, n = 1-6). Their ground-state geometric and electronic structures were systematically studied by various experimental methods including X-ray crystallographic analysis, variable temperature nuclear magnetic resonance, electron spin resonance, and superconducting quantum interference device measurements, supported by density functional theory and ab initio calculations. Moderate antiferromagnetic coupling between the fluorenyl radicals was observed, and moderate to large diradical and polyradical characters were calculated from dimer onward. Furthermore, their photophysical properties were estimated by steady-state, transient absorption, and two-photon absorption measurements, and their electrochemical properties were investigated by cyclic voltammetry/differential pulse voltammetry and spectro-electrochemical measurements. A clear chain length dependence of their optical, electrochemical, and magnetic properties was found for the oligomers with an odd or even number of spin centers, respectively.
| Original language | English |
|---|---|
| Pages (from-to) | 13048-13058 |
| Number of pages | 11 |
| Journal | Journal of the American Chemical Society |
| Volume | 138 |
| Issue number | 39 |
| DOIs | |
| Publication status | Published - 2016 Oct 5 |
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All Science Journal Classification (ASJC) codes
- Catalysis
- Chemistry(all)
- Biochemistry
- Colloid and Surface Chemistry
Cite this
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Stable 3,6-Linked Fluorenyl Radical Oligomers with Intramolecular Antiferromagnetic Coupling and Polyradical Characters. / Lu, Xuefeng; Lee, Sangsu; Kim, Jun Oh; Gopalakrishna, Tullimilli Y.; Phan, Hoa; Herng, Tun Seng; Lim, Zhenglong; Zeng, Zebing; Ding, Jun; Kim, Dongho; Wu, Jishan.
In: Journal of the American Chemical Society, Vol. 138, No. 39, 05.10.2016, p. 13048-13058.Research output: Contribution to journal › Article
TY - JOUR
T1 - Stable 3,6-Linked Fluorenyl Radical Oligomers with Intramolecular Antiferromagnetic Coupling and Polyradical Characters
AU - Lu, Xuefeng
AU - Lee, Sangsu
AU - Kim, Jun Oh
AU - Gopalakrishna, Tullimilli Y.
AU - Phan, Hoa
AU - Herng, Tun Seng
AU - Lim, Zhenglong
AU - Zeng, Zebing
AU - Ding, Jun
AU - Kim, Dongho
AU - Wu, Jishan
PY - 2016/10/5
Y1 - 2016/10/5
N2 - Organic radicals display unique physical structures and could become next generation functional materials. However, design and synthesis of stable neutral radicals with a significant polyradical character has been an enormous challenge for chemists. In this work, we synthesized a series of stable 3,6-linked, kinetically blocked fluorenyl radical oligomers up to hexamer (FR-n, n = 1-6). Their ground-state geometric and electronic structures were systematically studied by various experimental methods including X-ray crystallographic analysis, variable temperature nuclear magnetic resonance, electron spin resonance, and superconducting quantum interference device measurements, supported by density functional theory and ab initio calculations. Moderate antiferromagnetic coupling between the fluorenyl radicals was observed, and moderate to large diradical and polyradical characters were calculated from dimer onward. Furthermore, their photophysical properties were estimated by steady-state, transient absorption, and two-photon absorption measurements, and their electrochemical properties were investigated by cyclic voltammetry/differential pulse voltammetry and spectro-electrochemical measurements. A clear chain length dependence of their optical, electrochemical, and magnetic properties was found for the oligomers with an odd or even number of spin centers, respectively.
AB - Organic radicals display unique physical structures and could become next generation functional materials. However, design and synthesis of stable neutral radicals with a significant polyradical character has been an enormous challenge for chemists. In this work, we synthesized a series of stable 3,6-linked, kinetically blocked fluorenyl radical oligomers up to hexamer (FR-n, n = 1-6). Their ground-state geometric and electronic structures were systematically studied by various experimental methods including X-ray crystallographic analysis, variable temperature nuclear magnetic resonance, electron spin resonance, and superconducting quantum interference device measurements, supported by density functional theory and ab initio calculations. Moderate antiferromagnetic coupling between the fluorenyl radicals was observed, and moderate to large diradical and polyradical characters were calculated from dimer onward. Furthermore, their photophysical properties were estimated by steady-state, transient absorption, and two-photon absorption measurements, and their electrochemical properties were investigated by cyclic voltammetry/differential pulse voltammetry and spectro-electrochemical measurements. A clear chain length dependence of their optical, electrochemical, and magnetic properties was found for the oligomers with an odd or even number of spin centers, respectively.
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U2 - 10.1021/jacs.6b08138
DO - 10.1021/jacs.6b08138
M3 - Article
AN - SCOPUS:84990064468
VL - 138
SP - 13048
EP - 13058
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 39
ER -