Highly Stable Organic Bisradicals Protected by Mechanical Bonds
| Autor: | Yuanning Feng, Zhichang Liu, Wei Guang Liu, Huang Wu, J. Fraser Stoddart, Haochuan Mao, Yi Shi, William A. Goddard, Yunyan Qiu, Long Zhang, Hongliang Chen, Dengke Shen, Yang Jiao, Michael R. Wasielewski, Charlotte L. Stern, Kang Cai |
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| Rok vydání: | 2020 |
| Předmět: |
Chemistry
Radical Catenane Solid-state General Chemistry 010402 general chemistry Photochemistry Electrochemistry 01 natural sciences Biochemistry Catalysis 0104 chemical sciences law.invention Colloid and Surface Chemistry law Electrochromism Singlet state Absorption (chemistry) Electron paramagnetic resonance |
| Zdroj: | Journal of the American Chemical Society. 142(15) |
| ISSN: | 1520-5126 |
| Popis: | Two new highly charged [2]catenanes—namely, mHe[2]C·6PF₆ and mHo[2]C·6PF₆—were synthesized by exploiting radical host–guest templation between derivatives containing BIPY•+ radical cations and the meta analogue of cyclobis(paraquat-p-phenylene). In contrast to related [2]catenanes that have been isolated as air-stable monoradicals, both mHe[2]C·6PF₆ and mHo[2]C·6PF₆ exist as air-stable singlet bisradicals, as evidenced by both X-ray crystallography in the solid state and EPR spectroscopy in solution. Electrochemical studies indicate that the first two reduction peaks of these two [2]catenanes are shifted significantly to more positive potentials, a feature which is responsible for their extraordinary stability in air. The mixed-valence nature of the mono- and bisradical states endows them with unique NIR absorption properties, e.g., NIR absorption bands for the mono- and bisradical states observed at ∼1800 and ∼1450 nm, respectively. These [2]catenanes are potentially useful in applications that include NIR photothermal conversion, UV–vis–NIR multiple-state electrochromic materials, and multiple-state memory devices. Our findings highlight the principle of “mechanical-bond-induced stabilization” as an efficient strategy for designing persistent organic radicals. |
| Databáze: | OpenAIRE |
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