Stability, solution structure and X-ray crystallography of a copper (II) diamide complex

Abstract It has been shown that the inflammation associated with rheumatoid arthritis can be reduced using copper complexes. In order to improve the bioavailability of copper and hence efficacy, 3-(2-aminoacetamido)-N-(pyridin-2-ylmethyl)propanamide, H2(5 6 5)NH2, was designed as a potential chelator of copper. Solution equilibrium measurements show that the [Cu(LH-2)] species predominates at physiological pH and blood plasma speciation calculations predict that this ligand is able to mobilise Cu(II) in vivo. A structural study of the Cu(II)/H2(5 6 5)NH2 system was conducted in the solid and solution state using Uv–Vis, CD, 1H NMR and EPR spectroscopy and single crystal X-ray crystallography. The result indicate that the structure of [Cu(H2(5 6 5)NH2)H-2] in the solid and solution state are similar and confirm that, the metal binds to the pyridine nitrogen, the two amide nitrogens and the terminal amino group in a distorted square planar geometry.