Synthesis and Spectroscopic Characterization of <i>l</i>-Aspartic Acid Complexes with Metals of the Lanthanides Family

Abstract

The complexes between l-aspartic acid and metals of lanthanide series (La 3+ , Pr 3+ , Eu 3+ , Gd 3+ ) have been prepared and characterized using a variety of techniques including, infrared spectroscopy, 1 H NMR, 13C NMR, elemental analysis and metal contents. The sought metal effect on the electronic environment of the chiral carbon and its neighbouring atoms was observed in case of Europium and Praseodymium. The 13 C downfield shift indicates a lower electron density at the carbon with consequent downfield shift observed on the α-H attached to it increasing its acidity.

Improved Recovery and Selectivity of Lanthanide-Ion-Binding Cyclic Peptide Hosts by Changing the Position of Acidic Amino Acids

“…In the IR spectra, small shifts were observed in the signals corresponding to peptides (~1650 cm −1 (amide I, C=O) and 1540 cm −1 (amide II, N-CO)). Moreover, for the 3:l D-Ln complex, symmetric signals from the coordinating side-chain COO group was previously observed at 1420 cm −1 [46]. For the peptide-Ln complexes prepared in this study, a new absorbance signal was observed in this wavenumber range, indicating the successful complexation with Ln 3+ (Figure S3).…”