Crown Ether-Lanthanide Complexes Studied by CPL and TL. 3. Chirality in Europium Nitrate and Chloride Complexes of Methyl-Substituted 18-Crown-6 Ligands. Optical Activity of Two-Bladed Nitrate Propellers

Circularly polarized luminescence (CPL) and total luminescence (TL) have been used to investigate the solution structures of EuCl3 and Eu(NO3)3 complexes of chiral 18-crown-6 ligands dissolved in trifluoroethanol. The sources of dissymmetry sensed by the lanthanide cation in these complexes are discussed, with specific emphasis on the influence of the anion on the complex chirality. The chirality of the nitrate complexes contains a contribution arising from the presence of a dissymmetric two-bladed propeller formed by the opposing nitrate chelate rings. In contrast, the optical activity of the corresponding chloride complexes is due only to configurational and conformational contributions from the crown ether. © 1988, American Chemical Society. All rights reserved.

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Author Richard A. Palmer Chemistry