Chiral Bis(oxazoline) Ruthenium Complexes with Bipyridyl‐Type N‐Heteroaromatics: Comparative Stereochemical and Photochemical Characterization of their Λ‐ and Δ‐Diastereomeric Geminate Isomers |
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| Authors: | Prof?Dr Masayoshi Onishi Yoko Tashiro Dr Yasuhiro Arikawa Junko Nagaoka Prof?Dr Keisuke Umakoshi Dr Yusuke Sunada Prof?Dr Koichi Nozaki |
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| Institution: | 1. Department of Applied Chemistry, Faculty of Engineering, Nagasaki University, Nagasaki 852‐8521 (Japan), Fax: (+81)?95‐819‐2684;2. Graduate School of Science and Technology, Nagasaki University, Nagasaki 852‐8521 (Japan);3. Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka 816‐8580 (Japan);4. 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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| Keywords: | bis(oxazoline)s chiral complexes density functional calculations photoluminescence ruthenium |
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