NMR and chiroptical examination of the diastereoisomers of (S)-Eu-EOB-DTPA

The solution structure of the diastereoisomers of (S)-Eu--EOB--DTPA has been analysed by (1)H NMR, CD and CPL spectroscopy. Two major species exist which possess very similar (1)H NMR paramagnetic shifts and emission spectra, consistent with a 9-coordinate structure involving one bound water. Circularly polarised luminescence data are consistent with a common Lambda-helicity for each isomer; the isomers differ only in the absolute configuration of the central nitrogen atom.