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Charge-Neutral Amidinate-Containing Iridium Complexes Capable of Efficient Photocatalytic Water Reduction

Authors

  • Dr. Zhen-Tao Yu,

    Corresponding author
    1. National Laboratory of Solid State Microstructures and Eco-Materials and Renewable Energy Research Center, Department of Materials Science and Engineering, Nanjing University, (P. R. China)
    2. Kunshan Innovation Institute of Nanjing University, NO. 22, Hankou Road, Nanjing, Jiangsu 210093 (P. R. China), Fax: (+86) 25-8368-6632
    • National Laboratory of Solid State Microstructures and Eco-Materials and Renewable Energy Research Center, Department of Materials Science and Engineering, Nanjing University, (P. R. China)
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  • Yong-Jun Yuan,

    1. National Laboratory of Solid State Microstructures and Eco-Materials and Renewable Energy Research Center, Department of Materials Science and Engineering, Nanjing University, (P. R. China)
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  • Jian-Guang Cai,

    1. National Laboratory of Solid State Microstructures and Eco-Materials and Renewable Energy Research Center, Department of Materials Science and Engineering, Nanjing University, (P. R. China)
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  • Prof. Dr. Zhi-Gang Zou

    1. National Laboratory of Solid State Microstructures and Eco-Materials and Renewable Energy Research Center, Department of Materials Science and Engineering, Nanjing University, (P. R. China)
    2. Kunshan Innovation Institute of Nanjing University, NO. 22, Hankou Road, Nanjing, Jiangsu 210093 (P. R. China), Fax: (+86) 25-8368-6632
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Abstract

Two new charge-neutral iridium complexes, [Ir(tfm-ppy)2(N,N′-diisopropyl-benzamidinate)] (1) and [Ir(tfm-ppy)2(N,N′-diisopropyl-4-diethylamino-3,5-dimethyl-benzamidinate)] (2) (tfm-ppy=4-trifluoromethyl-2-phenylpyridine) containing an amidinate ligand and two phenylpyridine ligands were designed and characterised. The photophysical properties, electrochemical behaviours and emission quenching properties of these species were investigated. In concert with the cobalt catalyst [Co(bpy)3]2+, members of this new class of iridium complexes enable the photocatalytic generation of hydrogen from mixed aqueous solutions via an oxidative quenching pathway and display long-term photostability under constant illumination over 72 h; one of these species achieved a relatively high turnover number of 1880 during this time period. In the case of complex 1, the three-component homogeneous photocatalytic system proved to be more efficient than a related system containing a charged complex, [Ir(tfm-ppy)2(dtb-bpy)]+ (3, dtb-bpy=4,4′-di-tert-butyl-2,2′-dipyridyl). In combination with a rhodium complex as a water reduction catalyst, the performances of the systems using both complexes were also evaluated, and these systems exhibited a more efficient catalytic propensity for water splitting than did the cobalt-based systems that have been studied previously.

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