Benzo[4,5]cyclohepta[1,2-b]fluorene: an isomeric motif for pentacene containing linearly fused five-, six- and seven-membered rings

Xuejin Yang, Xueliang Shi, Naoki Aratani, Theo Goncalves, Kuo-Wei Huang, Hiroko Yamada, Chunyan Chi, Qian Miao

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39 Scopus citations


Benzo[4,5]cyclohepta[1,2-b]fluorene (5a), a new π-conjugated polycyclic hydrocarbon containing linearly fused six-, five-, six-, seven- and six-membered rings (C6-C5-C6-C7-C6), was designed and its stable derivatives 5b and 5c were synthesized. With 22 π electrons, 5a is an isomer of pentacene with quinoidal, dipolar ionic and diradical resonance forms. Molecules 5b and 5c were experimentally investigated with cyclic voltammetry, electronic absorption spectroscopy and X-ray crystallographic analysis, and theoretically studied by calculating the NICS value, diradical character and dipole moment. A comparison of 5a–c with pentacene and other pentacene analogues containing linearly fused five- or seven- membered rings was also conducted and discussed. It was found that 5b behaved as a p-type organic semiconductor in solution-processed thin film transistors with field effect mobility of up to 0.025 cm2/Vs.
Original languageEnglish (US)
Pages (from-to)6176-6181
Number of pages6
JournalChem. Sci.
Issue number9
StatePublished - 2016

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We are grateful to Prof. Michael M. Haley (University of
Oregon) and Prof. Yoshito Tobe (Osaka University) for their
kind support and helpful discussion. X. Yang and Q. Miao thank
financial support from the Research Grants Council of Hong
Kong (project number: GRF402412, CRF C4030-14G). X. Shi and
C. Chi thank financial support from MOE Tier 1 grant (R-143-
000-623-112), Tier 2 grant (MOE2014-T2-1-080) and Tier 3
programme (MOE2014-T3-1-004). N. Aratani and H. Yamada
thank support from the Grants-in-Aid for Scientific Research from JSPS (Nos. 16H02286, 26105004 and 26288038) and
CREST, JST. T. P. Gonçalves and K.-W. Huang acknowledge the
financial support from KAUST.


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