Potentiometric and spectral studies of complex formation in the Cu(II), 3′,5′-cyclic adenosine monophosphate, and tetramine systems

Abstract

Reactions in the systems composed of copper(II), 3′,5′-cyclic adenosine monophosphate (cAMP), and tetramines (PA) were studied. On the basis of potentiometric and spectroscopic data in metal-free systems, formation of molecular complexes (cAMP)H_x(PA), x = 2–4, was found. Stabilities of the complexes were determined and their centers of interactions were identified. In Cu(II)/cAMP, formation of Cu(cAMP) and Cu(cAMP)(OH) was observed, with the phosphate as the main site of metallation, while in ternary systems, formation of Cu(cAMP)H₄(Spm) and Cu(cAMP)(3,3,3-tet) was established. Characteristic differences in the coordination character of tetramines were found. In the Cu(II)/cAMP/Spm system, oxygens from the nucleotide phosphate are involved in metallation and protonated amines are engaged in noncovalent interaction with endocyclic nitrogens of nucleoside. In the Cu(II)/cAMP/3,3,3-tet system, a MLL′ complex is formed in which the inner coordination sphere includes polyamine nitrogens as well as the nucleotide phosphate.

Keywords:

• Copper(II)
• cAMP
• Tetramine
• Mixed complexes
• Molecular complexes

Acknowledgment

This work was supported by Grant No. NN 204001736 of the Ministry of Science and Higher Education (Poland).