Study of protonation and Zn(II), Cd(II), Cu(II) and Mn(II) complexation with a glutamic acid <i>N</i>-pyrimidine derivative: Crystal structure of a neutral Cd(II) complex of the bianionic ligand

The compound <i>N</i>-(4-amino-1-methyl-5-nitroso-6-oxo-1,6-dihydropyrimidin-2-yl)-(s)-glutamic acid (H3L) was synthesised and structurally characterised by analytical methods and ¹H, ¹³C and ¹⁵N NMR spectroscopy. This compound (H₃L) shows the same topology as other model receptors previously used to develop chemical functionalization at the surface of an active carbon when they adsorb on it. Protonation of H₃L and its coordination ability towards Cd²⁺, Zn²⁺, Cu²⁺ and Mn²⁺ ions in water solution was also studied by potentiometric methods, UV–Vis and ¹H, ¹³C NMR spectroscopies. The obtained results allow us to fit the operative conditions for the use of the activated carbon–H₃L adsorbent for the retaining of the above-mentioned metal ions in aqueous solutions. The molecular structure of {[Cd(HL)H₂O] • ₃H₂O}<i>_n</i> was solved by single-crystal X-ray diffraction methods.