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Large π-Conjugated Chromophores Derived from Tetrathiafulvalene

Authors

  • Dr. Hongpeng 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, Université de Genève, 30 Quai Ernest-Ansermet, CH-1211 Genève 4 (Switzerland)
    2. Present address: The College of Chemistry and Molecular Engineering, Zhengzhou University, 100 Kexue Road, 450001 Zhengzhou, Henan (P.R. China)
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  • Prof. Andreas Hauser,

    1. Département de Chimie Physique, 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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  • 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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Abstract

A large π-conjugated chromophore composed of two dipyrido[3,2-a:2′,3′-c]phenazine units directly fused to the central tetrathiafulvalene core has been prepared as a bridging ligand and its strong binding ability to Ru2+ to form a new dinuclear complex is presented. The electronic absorption and luminescence spectra and the electrochemical behavior of the free ligand and the Ru2+ complex have been investigated in detail. The free ligand shows a very strong band in the UV region consistent with ligand-centered π–π* transitions and an intense broad band in the visible region that corresponds to an intramolecular charge-transfer (ILCT) transition. Upon coordination, a metal-to-ligand charge-transfer band appears at 22520 cm−1, and the ILCT band is bathochromically shifted by 1620 cm−1. These electrochemically amphoteric chromophores have also been characterized by spectro-electrochemical methods. The oxidized radical species of the free ligand show a strong tendency to undergo aggregation, in which long-distance attractive interactions overcome the electrostatic repulsion. Moreover, these two new chromophores reveal an ILCT fluorescence with large solvent-dependent Stokes shifts and quantum efficiencies of 0.052 for the free ligand and 0.016 for its dinuclear Ru2+ complex in CH2Cl2.

Abstract

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