Stable tetrabenzo-Chichibabin's hydrocarbons: Tunable ground state and unusual transition between their closed-shell and open-shell resonance forms
Type
ArticleAuthors
Zeng, ZebingSung, Youngmo
Bao, Nina
Tan, Davin
Lee, Richmond
Zafra, José Luis
Lee, Byungsun
Ishida, Masatoshi
Ding, Jun
Lõpez Navarrete, Juan Teodomiro
Li, Yuan
Zeng, Wangdong
Kim, Dongho
Huang, Kuo-Wei

Webster, Richard D.
Casado, Juan
Wu, Jishan
KAUST Department
Biological and Environmental Sciences and Engineering (BESE) DivisionChemical Science Program
Homogeneous Catalysis Laboratory (HCL)
KAUST Catalysis Center (KCC)
Physical Science and Engineering (PSE) Division
Date
2012-08-22Online Publication Date
2012-08-22Print Publication Date
2012-09-05Permanent link to this record
http://hdl.handle.net/10754/562319
Metadata
Show full item recordAbstract
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 FeCl 3 and/or concentrated H 2SO 4. The open-shell 2-OS also exhibited a large two-photon absorption (TPA) cross section (760 GM at 1200 nm). © 2012 American Chemical Society.Citation
Zeng, Z., Sung, Y. M., Bao, N., Tan, D., Lee, R., Zafra, J. L., … Wu, J. (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. doi:10.1021/ja3050579Sponsors
J.W. acknowledges financial support from the BMRC-NMRC grant (no. 10/1/21/19/642), MOE Tier 2 grant (MOE2011-T2-2-130), and IMRE Core funding (IMRE/10-1P0509). The work at Yonsei University was supported by WCU (World Class University) programs (R32-2010-10217-0) and an AFSOR/APARD grant (no. FA2386-09-1-4092). K.-W.H. acknowledges financial support from KAUST. The work at the University of Malaga was supported by the Ministerio de Educacion y Ciencia (MEC) of Spain and by FEDER funds (project CTQ2009-10098 and to the Junta de Andalucia for the research project PO9-4708). We thank Dr. Tan Geok-Kheng for crystallographic analysis.Publisher
American Chemical Society (ACS)Relations
Is Supplemented By:- [Dataset]
Zeng, Z., Sung, Y. M., Bao, N., Tan, D., Lee, R., Zafra, J. L., … Wu, J. (2013). CCDC 945080: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/cc10qfgm. DOI: 10.5517/cc10qfgm HANDLE: 10754/624233 - [Dataset]
Zeng, Z., Sung, Y. M., Bao, N., Tan, D., Lee, R., Zafra, J. L., … Wu, J. (2013). CCDC 945081: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/cc10qfhn. DOI: 10.5517/cc10qfhn HANDLE: 10754/624234
ae974a485f413a2113503eed53cd6c53
10.1021/ja3050579