Electrochemistry of copper complexes with polyaza[n]paracyclophanes. Influence of ATP as an exogen ligand on the relative stability of the Cu(II) andCu(I) oxidation states

Interaction of Cu2+ with the macrocycle 2,6,9,13-tetraaza[14]paracyclophane (L) and ATP has been followed by pH-metric titration, cyclic voltammetry a nd differential pulse voltammetry (DPV). Mixed adduct species with various degrees of protonation were found to be stable for pH > 4. In neutral and a lkaline media reduction of mixed complexes occurs in a two-electron quasi-r eversible step in contrast with binary Cu2+-L complexes which display two s uccessive one-electron couples. The potentiometric and voltammetric data su ggest that in ternary adducts ATP binds to Cu2+ ions through the phosphate chain and one N-site of the adenine ring system. (C) 2000 Elsevier Science S.A. All rights reserved.