Binding of ureas and amides to a Cu(II) terpyridine complex in methanol

The binding of seven ureas and amides to Cu(terpy)2+ in methanol has been studied by EPR, NMR and UV–Vis spectroscopy. The association constants range from 6.5 M−1 for acetamide to 45.3 M−1 for propyleneurea and correlate with the gas phase basicity of ligands. In methanol/water mixtures the affinity drops rapidly on increase in water content to 20 vol.%, but the binding of propyleneurea is detectable with K = 4.1 M−1 even in pure aqueous medium.