Heteronuclear complexes of phosphocreatine with copper(II) and magnesium(II) ions

Abstract

It has been found that in the binary systems Mg(II)/phosphocreatine and Cu(II)/phosphocreatine at low pH, metal ions mainly coordinate via the phosphate group. At higher pH for copper(II) system, the efficiency of-PO 3 2group is low and coordination takes place via amine and carboxyl groups (Mg 2? is still coordinated to phosphate group). Differences in the coordination mode for copper and magnesium ions in binary systems at high pH suggested that it would be interesting to determine the mode of coordination in heteronuclear complexes and the coordination competitiveness of metal ions towards phosphate group at low and at physiological pH. The formation of heteronuclear complexes of phosphocreatine with Mg 2? and Cu 2? ions was investigated. The overall stability constants of these species were determined by the potentiometric studies and the coordination mode was concluded on the basis of several spectral investigations (EPR, Visible Spectroscopy, 2D 1 H-15 N NMR, 31 P NMR and FT-IR).

Biocoordination reactions in copper(II) ions and phosphocholine systems including pyrimidine nucleosides and nucleotides

“…On the basis of the analysis of UV-Vis (d–d transition energy), EPR (g ‖ as well as A ‖ parameters) and 13 C and 31 P NMR (changes in the chemical shifts between free ligand and ligand in complex), the coordination mode was specified. As reported in previous publications, there is a relationship between the type and number of donor atoms in the inner coordination sphere of Cu(II) complexes and UV-Vis, as well as the spectral parameters of EPR 32 – 34 . In the protonated form CuH(cholP) 2 only one oxygen atom from the phosphate group is in the inner coordination sphere (λ max = 801 nm, g ‖ = 2.39, A ‖ = 147 10 −4 cm −1 ), (Table 2 , Fig.…”

The Influence of pH on Complexation Process of Copper(II) Phosphoethanolamine to Pyrimidine Nucleosides

“…The coordination mode was established on the basis of the analysis of spectral parameters d-d transition energy in the UV–Vis spectra and g ‖ as well as A ‖ values in EPR studies (taking into consideration the relation of these values to the number of coordinated donor atoms). The conclusions were supported with the analysis of the IR spectra, changes in chemical shifts in the 31 P and 13 C NMR spectra of the ligand in complexes with respect to those of the free ligand, taking into regard our experience, and careful analysis of the results for paramagnetic ions [ 17 , 23 , 36 ].…”

Biocoordination reactions in copper(II) ions and phosphocholine systems including pyrimidine nucleosides and nucleotides

“…On the basis of the analysis of UV-Vis (d-d transition energy), EPR (g ‖ as well as A ‖ parameters) and 13 C and 31 P NMR (changes in the chemical shifts between free ligand and ligand in complex), the coordination mode was speci ed. As reported in previous publications, there is a relationship between the type and number of donor atoms in the inner coordination sphere of Cu(II) complexes and UV-Vis, as well as the spectral parameters of EPR [27][28][29] . In the protonated form CuH(cholP) 2 only one oxygen atom from the phosphate group is in the inner coordination sphere (λ max = 801 nm, g ‖ = 2.39, A ‖ = 147 • 10 − 4 cm − 1 ), (Table 2., Fig.…”