Title
Electronic chirality inversion of lanthanide complex induced by achiral molecules
Author
Satoshi Wada, Yuichi Kitagawa, Takayuki Nakanishi, Masayuki Gon, Kazuo Tanaka, Koji Fushimi, Yoshiki Chujo, Yasuchika Hasegawa
Year
2018
Journal
Scientific Reports
Abstract
A novel mechanism for chiroptical activity inversion based on the electronic structure of metal complexes without Λ- or Δ-type structure change was demonstrated spectroscopically and theoretically. To demonstrate the mechanism, a europium (Eu(III)) complex with chiral (+)-3-(trifluoroacetyl)camphor (+tfc) and achiral triphenylphosphine oxide (tppo) was prepared. The steric and electronic structures of the Eu(III) complex were adjusted by additional achiral tppo and coordinating acetone molecules, and were characterised by 1H NMR, photoluminescence, and emission lifetime measurements. The optical activity of the Eu(III) complex in solution was evaluated by circularly polarized luminescence (CPL) measurements. CPL sign inversion, which was independent of Λ- or Δ-type structure changes from the spectroscopic viewpoint, and a drastic CPL intensity enhancement were observed depending on the external achiral molecules around Eu(III) ion. These phenomena provide the first clarification of optical activity change associated with electronic structure rather than chiral coordination structure-type (Λ or Δ) under external environments.
Full Article
Instrument
CPL-200
Keywords
Circularly polarized luminescence, Stereochemistry, Coordination chemistry, Inorganic chemistry