ABSORPTION AND CIRCULAR DICHROIC SPECTRAL STUDIES OF EUROPIUM(3) COMPLEXES WITH SUGAR ACIDS,AND AMINO ACIDS, WITH REMARKS ON HYPERSENSITIVITY

Chelate complexes of Eu(III) with sugar acids, both in the acid and neutral pH ranges, are demonstrated. Complexing takes place through the carboxylate group and the γ-hydroxyl, revealed by the CD relations of the gluconic and galactonic acid complexes. In addition to chelate complexes of the -amino acids in the neutral to alkaline pH range, monodentate complexes with the zwitterionic form are demonstrated. Besides the known “hypersensitive” behavior of the 7Fo → 5D2 transition in the absorption spectrum, hypersensitivity is also indicated for the 7FO → 5DO and 7F0 → 5D2 transitions and perhaps in others which share the relation ∣ΔJ∣ = 0, 2. A requirement seems to be binding of an anion, which may include reduction of symmetry. Some potentially revealing characteristics of the CD spectra are pointed out. © 1969, American Chemical Society. All rights reserved.