Studies by 1H NMR and UV-Vis spectroscopy of the molecular recognition of histamine by copper and zinc complexes of polyazamacrocyclic ligands

Abstracts The recognition of histamine with copper and zinc complexes of polyazamacrocyclic ligans was studied. The molecular recognition of histamine from the metal complexes was determined by UV-Vis and 1H NMR spectra in solution. In the coordination study of histamine with the Cu2+ complexes, different changes were observed in the charge transfer bands and in the d-d bands of the metal complexes. These observations indicate a change in the conformational geometry of the complexes and the formation of the adduct with histamine. According with the analysis by 1H NMR, the chemical shifts of the H2 and H5 hydrogens of the histamine aromatic ring are caused by the interaction with Zn2+ complexes, the widening of the H2 signal suggests that the coordination occurs between the N3 of the imidazole ring of the histamine and the Zn2+ ion. These results showed the formation of histamine adducts with the Cu2+ and Zn2+ complexes, to give rise to a ternary complex.