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

X. Yang, X. Shi, N. Aratani, T.P. Gonçalves, K.-W. Huang, H. Yamada, C. Chi, Q. Miao
Chem. Sci., 7, pp. 6176-6181, (2016)

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

Keywords

Isomeric motif, Pentacene, Membered rings

Abstract

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 a field effect mobility of up to 0.025 cm2 V−1 s−1.

Code

DOI: 10.1039/C6SC01795A

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