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Targeting π-Conjugated Multiple Donor–Acceptor Motifs Exemplified by Tetrathiafulvalene-Linked Quinoxalines and Tetrabenz[bc,ef,hi,uv]ovalenes: Synthesis, Spectroscopic, Electrochemical, and Theoretical Characterization

Authors

  • Dr. Hong-Peng Jia,

    1. Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern (Switzerland), Fax: (+41) 31-631-3995
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  • Dr. Jie Ding,

    1. Département de chimie physique, Sciences II, Université de Genève, 30, Quai Ernest-Ansermet, CH-1211 Genève 4 (Switzerland)
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  • Dr. Ying-Fen Ran,

    1. Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern (Switzerland), Fax: (+41) 31-631-3995
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  • Dr. Shi-Xia Liu,

    Corresponding author
    1. Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern (Switzerland), Fax: (+41) 31-631-3995
    • Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern (Switzerland), Fax: (+41) 31-631-3995

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  • Dr. Carmen Blum,

    1. Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern (Switzerland), Fax: (+41) 31-631-3995
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  • Dr. Irina Petkova,

    1. Département de chimie physique, Sciences II, Université de Genève, 30, Quai Ernest-Ansermet, CH-1211 Genève 4 (Switzerland)
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  • Prof. Andreas Hauser,

    1. Département de chimie physique, Sciences II, Université de Genève, 30, Quai Ernest-Ansermet, CH-1211 Genève 4 (Switzerland)
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  • Prof. Silvio Decurtins

    1. Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern (Switzerland), Fax: (+41) 31-631-3995
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Abstract

An efficient synthetic approach to a symmetrically functionalized tetrathiafulvalene (TTF) derivative with two diamine moieties, 2-[5,6-diamino-4,7-bis(4-pentylphenoxy)-1,3-benzodithiol-2-ylidene]-4,7-bis(4-pentylphenoxy)-1,3-benzodithiole-5,6-diamine (), is reported. The subsequent Schiff-base reactions of afford large π-conjugated multiple donor–acceptor (D–A) arrays, for example, the triad 2-[4,9-bis(4-pentylphenoxy)-1,3-dithiolo[4,5-g]quinoxalin-2-ylidene]-4,9-bis(4-pentylphenoxy)-1,3-dithiolo[4,5-g]quinoxaline () and the corresponding tetrabenz[bc,ef,hi,uv]ovalene-fused pentad , in good yields and high purity. The novel redox-active nanographene is so far the largest known TTF-functionalized polycyclic aromatic hydrocarbon (PAH) with a well-resolved 1H NMR spectrum. The electrochemically highly amphoteric pentad and triad exhibit various electronically excited charge-transfer states in different oxidation states, thus leading to intense optical intramolecular charge-transfer (ICT) absorbances over a wide spectral range. The chemical and electrochemical oxidations of result in an unprecedented TTF⋅+ radical cation dimerization, thereby leading to the formation of [⋅+]2 at room temperature in solution due to the stabilizing effect, which arises from strong π–π interactions. Moreover, ICT fluorescence is observed with large solvent-dependent Stokes shifts and quantum efficiencies of 0.05 for and 0.035 for in dichloromethane.

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