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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
Author(s) -
Onishi Masayoshi,
Tashiro Yoko,
Arikawa Yasuhiro,
Nagaoka Junko,
Umakoshi Keisuke,
Sunada Yusuke,
Nozaki Koichi
Publication year - 2011
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201000738
Subject(s) - diastereomer , chemistry , ruthenium , excited state , oxazoline , photochemistry , phosphorescence , stereochemistry , crystallography , organic chemistry , fluorescence , catalysis , nuclear physics , physics , quantum mechanics
Diastereomeric geminate pairs of chiral bis(2‐oxazoline) ruthenium complexes with bipyridyl‐type N ‐heteroaromatics, Λ‐ and Δ‐[Ru( L‐ L) 2 ( i Pr‐biox)] 2+ ( i Pr‐biox=(4 S ,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 BF 4 and PF 6 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 i Pr‐biox. Furthermore, photoluminescence properties of the two Λ,Δ‐diastereomeric series are discussed with reference to [Ru(bpy) 3 ] 2+ .