LAUSR

Abstract Complexation reactions of Cu(II) in the system with l -lysine as well as biogenic amines – PA (putrescine – Put, spermidine – Spd and spermine – Spm) were investigated. It was found that at low pH in Cu(II)/Lys/Put and Cu(II)/Lys/Spm systems molecular complexes of M(Lys)⋯PA type are formed with putrescine and spermine in the outer coordination sphere. In contrast to the above systems, molecular adducts do not occur in the spermidine systems. At higher pH, heteroligand species are formed with polyamines in the inner coordination sphere. In solution, the molecular composition, stability and mode of coordination in Cu(Lys)Hx(PA) species were established using potentiometric and spectral techniques. In the glassy state at 77 K, only stationary Cu(II)-complexes exist. According to the EPR spectra, lysine is a strongly coordinating molecule compared to the polyamines. The influence of metal ions on the formation of binary Lys/Pa molecular complexes was calculated. It was found for the binary Lys/Spm system, that the introduction of decreasing amounts of Cu(II) to the binary ligand1/ligand2 systems to the level of 0.01 mM resulted in changes in the concentration of the molecular complexes in aqueous solution. At the level of Cu(II) above 5 mM all molecular complexes disappear.