Dithienyl Acenedithiophenediones as New π-Extended Quinoidal Cores: Synthesis and Properties

Kohsuke Kawabata, Itaru Osaka, Masanori Sawamoto, José L. Zafra, Paula Mayorga Burrezo, Juan Casado, Kazuo Takimiya

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

We have synthesized two isomeric pairs of benzo- and naphthodithiophenediones with two flanking thiophenes and characterized them by single-crystal X-ray analysis, cyclic voltammetry, steady-state optical electronic absorption and emission spectroscopies, transient absorption spectroscopy, and vibrational spectroscopies with in situ spectroelectrochemistry techniques, and then compared them with the thieno[3,2-b]thiophene-2,5-dione counterpart that we previously reported. The results show that the central acenedithiophenedione cores have quinoidal conjugation with closed-shell character. The π-extension of the quinoidal core raises (lowers) the HOMO (LUMO) energy levels of the triads, resulting in the drastic reduction of their energy gaps from approximately 2.0 eV to 1.1 eV. Owing to the electron-withdrawing nature of the carbonyl terminal group at the quinoidal core, the triads have low-lying LUMO energy levels ranging from −3.9 eV to −4.3 eV, and can be regarded as strong electron-acceptor building units. Interestingly, the pairs of structural isomers have similar electronic structures in both the neutral and charged states despite the different shapes (linear and angular) and/or symmetry (C2h and C2v) of the acenedithiophenedione cores.

Original languageEnglish
Pages (from-to)4579-4589
Number of pages11
JournalChemistry - A European Journal
Volume23
Issue number19
DOIs
Publication statusPublished - 2017 Apr 3
Externally publishedYes

Keywords

  • donor–acceptor systems
  • electronic structure
  • organic electronics
  • spectroscopic properties
  • thienoquinoid

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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