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Chiral Bis(oxazoline) Ruthenium Complexes with Bipyridyl-Type N-Heteroaromatics: Comparative Stereochemical and Photochemical Characterization of their Λ- and Δ-Diastereomeric Geminate Isomers

Authors

  • Prof. Dr. Masayoshi Onishi,

    Corresponding author
    1. Department of Applied Chemistry, Faculty of Engineering, Nagasaki University, Nagasaki 852-8521 (Japan), Fax: (+81) 95-819-2684
    • Masayoshi Onishi, Department of Applied Chemistry, Faculty of Engineering, Nagasaki University, Nagasaki 852-8521 (Japan), Fax: (+81) 95-819-2684

      Koichi Nozaki, Graduate School of Science and Engineering, University of Toyama, Toyama 930-8555 (Japan), Fax: (+81) 76-445-6549

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  • Yoko Tashiro,

    1. Department of Applied Chemistry, Faculty of Engineering, Nagasaki University, Nagasaki 852-8521 (Japan), Fax: (+81) 95-819-2684
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  • Dr. Yasuhiro Arikawa,

    1. Graduate School of Science and Technology, Nagasaki University, Nagasaki 852-8521 (Japan)
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  • Junko Nagaoka,

    1. Department of Applied Chemistry, Faculty of Engineering, Nagasaki University, Nagasaki 852-8521 (Japan), Fax: (+81) 95-819-2684
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  • Prof. Dr. Keisuke Umakoshi,

    1. Department of Applied Chemistry, Faculty of Engineering, Nagasaki University, Nagasaki 852-8521 (Japan), Fax: (+81) 95-819-2684
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  • Dr. Yusuke Sunada,

    1. Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan)
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  • Prof. Dr. Koichi Nozaki

    Corresponding author
    1. Graduate School of Science and Engineering, University of Toyama, Toyama 930-8555 (Japan), Fax: (+81) 76-445-6549
    • Masayoshi Onishi, Department of Applied Chemistry, Faculty of Engineering, Nagasaki University, Nagasaki 852-8521 (Japan), Fax: (+81) 95-819-2684

      Koichi Nozaki, Graduate School of Science and Engineering, University of Toyama, Toyama 930-8555 (Japan), Fax: (+81) 76-445-6549

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Abstract

Diastereomeric geminate pairs of chiral bis(2-oxazoline) ruthenium complexes with bipyridyl-type N-heteroaromatics, Λ- and Δ-[Ru(L-L)2(iPr-biox)]2+ (iPr-biox=(4S,4′S)-4,4′-diisopropyl-2,2′-bis(2-oxazoline); L-L=2,2′-bipyridyl (bpy) for 1 Λ and 1 Δ, 4,4′-dimethyl-2,2′-bipyridyl (dmbpy) for 2 Λ and 2 Δ, and 1,10-phenanthroline (phen) for 3 Λ and 3 Δ), were separated as BF4 and PF6 salts and were subjected to the comparative studies of their stereochemical and photochemical characterization. DFT calculations of 1 Λ and 1 Δ electronic configurations for the lowest triplet excited state revealed that their MO-149 (HOMO) and MO-150 (lower SOMO) characters are interchanged between them and that the phosphorescence-emissive states are an admixture of a Ru-to-biox charge-transfer state and an intraligand excited state within the iPr-biox. Furthermore, photoluminescence properties of the two Λ,Δ-diastereomeric series are discussed with reference to [Ru(bpy)3]2+.

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