Please use this identifier to cite or link to this item: https://hdl.handle.net/10356/97613
Title: Stable tetrabenzo-chichibabin’s hydrocarbons : tunable ground state and unusual transition between their closed-shell and open-shell resonance forms
Authors: Zeng, Zebing
Sung, Young Mo
Bao, Nina
Tan, Davin
Lee, Richmond
Zafra, José L.
Lee, Byung Sun
Ishida, Masatoshi
Ding, Jun
López Navarrete, Juan T.
Li, Yuan
Zeng, Wangdong
Kim, Dongho
Huang, Kuo-Wei
Webster, Richard David
Casado, Juan
Wu, Jishan
Issue Date: 2012
Source: Zeng, Z., Sung, Y. M., Bao, N., Tan, D., Lee, R., Zafra, J. L., et al. (2012). Stable tetrabenzo-chichibabin’s hydrocarbons : tunable ground state and unusual transition between their closed-shell and open-shell resonance forms. Journal of the American Chemical Society, 134(35), 14513-14525.
Series/Report no.: Journal of the American chemical society
Abstract: Stable open-shell polycyclic aromatic hydrocarbons (PAHs) are of fundamental interest due to their unique electronic, optical, and magnetic properties and promising applications in materials sciences. Chichibabin’s hydrocarbon as a classical open-shell PAH has been investigated for a long time. However, most of the studies are complicated by their inherent high reactivity. In this work, two new stable benzannulated Chichibabin’s hydrocarbons 1-CS and 2-OS were prepared, and their electronic structure and geometry in the ground state were studied by various experiments (steady-state and transient absorption spectra, NMR, electron spin resonance (ESR), superconducting quantum interference device (SQUID), FT Raman, X-ray crystallographic etc.) and density function theory (DFT) calculations. 1-CS and 2-OS exhibited tunable ground states, with a closed-shell quinoidal structure for 1-CS and an open-shell biradical form for 2-OS. Their corresponding excited-state forms 1-OS and 2-CS were also chemically approached and showed different decay processes. The biradical 1-OS displayed an unusually slow decay to the ground state (1-CS) due to a large energy barrier (95 ± 2.5 kJ/mol) arising from severe steric hindrance during the transition from an orthogonal biradical form to a butterfly-like quinoidal form. The quick transition from the quinoidal 2-CS (excited state) to the orthogonal biradicaloid 2-OS (ground state) happened during the attempted synthesis of 2-CS. Compounds 1-CS and 2-OS can be oxidized into stable dications by FeCl3 and/or concentrated H2SO4. The open-shell 2-OS also exhibited a large two-photon absorption (TPA) cross section (760 GM at 1200 nm).
URI: https://hdl.handle.net/10356/97613
http://hdl.handle.net/10220/11221
DOI: 10.1021/ja3050579
Rights: © 2012 American Chemical Society.
Fulltext Permission: none
Fulltext Availability: No Fulltext
Appears in Collections:SPMS Journal Articles

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