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Structural, Photophysical, and Electrophosphorescent Properties of Platinum(II) Complexes Supported by Tetradentate N2O2 Chelates

Authors

  • Yong-Yue Lin Dr.,

    1. Department of Chemistry and HKU-CAS Joint Laboratory on New Materials The University of Hong Kong Pokfulam Road Hong Kong SAR, China, Fax: (+852) 2857-1586
    2. Department of Chemistry Yunnan Normal University Kunming 650092, China
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  • Siu-Chung Chan,

    1. Department of Chemistry and HKU-CAS Joint Laboratory on New Materials The University of Hong Kong Pokfulam Road Hong Kong SAR, China, Fax: (+852) 2857-1586
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  • Michael C. W. Chan Dr.,

    1. Department of Chemistry and HKU-CAS Joint Laboratory on New Materials The University of Hong Kong Pokfulam Road Hong Kong SAR, China, Fax: (+852) 2857-1586
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  • Yuan-Jun Hou Dr.,

    1. Department of Chemistry and HKU-CAS Joint Laboratory on New Materials The University of Hong Kong Pokfulam Road Hong Kong SAR, China, Fax: (+852) 2857-1586
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  • Nianyong Zhu Dr.,

    1. Department of Chemistry and HKU-CAS Joint Laboratory on New Materials The University of Hong Kong Pokfulam Road Hong Kong SAR, China, Fax: (+852) 2857-1586
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  • Chi-Ming Che Prof. Dr.,

    1. Department of Chemistry and HKU-CAS Joint Laboratory on New Materials The University of Hong Kong Pokfulam Road Hong Kong SAR, China, Fax: (+852) 2857-1586
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  • Yu Liu,

    1. Key Laboratory for Supramolecular Structure and Spectroscopy of Ministry of Education Jilin University Changchun 130023, China
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  • Yue Wang Prof.

    1. Key Laboratory for Supramolecular Structure and Spectroscopy of Ministry of Education Jilin University Changchun 130023, China
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Abstract

We present an examination of the structural and photophysical characteristics of [Pt(N2O2)] complexes bearing bis(phenoxy)diimine auxiliaries (diimine=4,7-Ph2phen (1) and 4,4′-tBu2bpy (2)) that are tetradentate relatives of the quinolinolato (q) ligand. These neutral derivatives display high thermal stability (>400 °C in N2). While the crystal lattice in 1 consists of (head-to-tail)-interacting dimers, molecules of 2 are arranged into infinitely stacked planar sheets with possible π–π interactions but no close Pt⋅⋅⋅Pt contacts. Complexes 1 and 2 exhibit moderately intense low-energy UV/Vis absorptions around λ=400–500 nm that undergo negative solvatochromic shifts. Both derivatives are highly luminescent in solution at 298 K with emission lifetimes in the μs range, and mixed 3[l→π*(diimine)] (l=lone pair/phenoxide) and 3[Pt(d)→π*(diimine)] charge-transfer states are tentatively assigned. The excited-state properties of 2 are also investigated by time-resolved absorption spectroscopy and by quenching experiments with pyridinium acceptors to estimate the excited-state redox potential. These emitters have been employed as electrophosphorescent dopants in multilayer OLEDs. Differences between the brightness, color, and overall performance of devices incorporating 1 and 2 are attributed to the influence of the diimine substituents.

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