Synthesis, One- and Two-Photon Photophysical and Excited-State Properties, and Sensing Application of a New Phosphorescent Dinuclear Cationic Iridium(III) Complex

Authors

  • Dr. Wen-Juan Xu,

    1. Key Laboratory for Organic Electronics and Information, Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210046 (P. R. China)
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  • Dr. Shu-Juan Liu,

    1. Key Laboratory for Organic Electronics and Information, Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210046 (P. R. China)
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  • Xin Zhao,

    1. Key Laboratory for Organic Electronics and Information, Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210046 (P. R. China)
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  • Dr. Ning Zhao,

    1. State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100 (P. R. China)
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  • Dr. Zhi-Qiang Liu,

    1. State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100 (P. R. China)
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  • Hang Xu,

    1. Key Laboratory for Organic Electronics and Information, Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210046 (P. R. China)
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  • Hua Liang,

    1. Key Laboratory for Organic Electronics and Information, Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210046 (P. R. China)
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  • Prof. Dr. Qiang Zhao,

    Corresponding author
    1. Key Laboratory for Organic Electronics and Information, Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210046 (P. R. China)
    • Key Laboratory for Organic Electronics and Information, Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210046 (P. R. China)
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  • Prof. Dr. Xiao-Qiang Yu,

    Corresponding author
    1. State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100 (P. R. China)
    • State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100 (P. R. China)
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  • Prof. Dr. Wei Huang

    Corresponding author
    1. Key Laboratory for Organic Electronics and Information, Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210046 (P. R. China)
    • Key Laboratory for Organic Electronics and Information, Displays and Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210046 (P. R. China)
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Abstract

A new phosphorescent dinuclear cationic iridium(III) complex (Ir1) with a donor–acceptor–π-bridge–acceptor–donor (D[BOND]A[BOND]π[BOND]A[BOND]D)-conjugated oligomer (L1) as a N^N ligand and a triarylboron compound as a C^N ligand has been synthesized. The photophysical and excited-state properties of Ir1 and L1 were investigated by UV/Vis absorption spectroscopy, photoluminescence spectroscopy, and molecular-orbital calculations, and they were compared with those of the mononuclear iridium(III) complex [Ir(Bpq)2(bpy)]+PF6 (Ir0). Compared with Ir0, complex Ir1 shows a more-intense optical-absorption capability, especially in the visible-light region. For example, complex Ir1 shows an intense absorption band that is centered at λ=448 nm with a molar extinction coefficient (ε) of about 104, which is rarely observed for iridium(III) complexes. Complex Ir1 displays highly efficient orange–red phosphorescent emission with an emission wavelength of 606 nm and a quantum efficiency of 0.13 at room temperature. We also investigated the two-photon-absorption properties of complexes Ir0, Ir1, and L1. The free ligand (L1) has a relatively small two-photon absorption cross-section (δmax=195 GM), but, when complexed with iridium(III) to afford dinuclear complex Ir1, it exhibits a higher two-photon-absorption cross-section than ligand L1 in the near-infrared region and an intense two-photon-excited phosphorescent emission. The maximum two-photon-absorption cross-section of Ir1 is 481 GM, which is also significantly larger than that of Ir0. In addition, because the strong B[BOND]F interaction between the dimesitylboryl groups and F ions interrupts the extended π-conjugation, complex Ir1 can be used as an excellent one- and two-photon-excited “ON–OFF” phosphorescent probe for F ions.

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