Metal complexes of thymidine — a study of binary and ternary systems with bivalent and trivalent metal ions in solution

Abstract

The interaction of bivalent I-Cu(II), Ni(II), Zn(II), Co(II), Mg(II), Ca(II)] and trivalent I-La(III), Pr(III), Nd(III), Sm(III), Gd(llI), Dy(IIl)] metal ions with thymidine both in binary and ternary systems have been investigated by potentiometric pH measurements at 35~ and 0-10 M (KNO2) ionic strength. The secondary ligands used in this investigation were glycine, histidine, histamine, o-phenanthroline and a, ~,'-bipyridyl. The various stability constants pertaining to the above interactions were computed and compared. The influence of pH on the concentrations of several species present in aqueous solution, has been assessed. The effects of (i) charge on the metal ions, and (ii) the presence of a methyl group on the pyrimidine ring, on the stabilities of complexes have been assessed. A comparison with the corresponding constants of uridine has been made. Thymidine forms more stable complexes than uridine.Keywords. Metal complexes of thymidine; binary and ternary systems; bivalent and trivalent metal ions.

Solution Studies of Some Binary and Ternary Lanthanide Complexes

“…Choppin et al studied lanthanide complexation by benzoic acid and isophthalic acid and suggested that in the latter ligand, steric effects prevent simultaneous binding to both carboxylate sites. Studies on complex formation by tripositive rare earth ions with biologically important ligands are in progress because of their role in biochemical processes, and some lanthanide complexes with nucleosides/nucleotides are also available in the literature. − To the best of our knowledge, no examples of the interaction of uracil and its halo derivatives with lanthanides in the presence of benzoic acid/its derivatives are known to date. The present paper reports studies on the interaction of uracil (Ur), 5-fluorouracil (FUr), 5-chlorouracil (ClUr), and 5-bromouracil (BrUr) as one ligand and benzoic acid (OBz), 4-nitrobenzoic acid (NBz), 4-fluorobenzoic acid (FBz), 4-chlorobenzoic acid (ClBz), and 4-bromobenzoic acid (BrBz) as another ligand with Eu(III), Gd(III), and Tb(III) in 1:1:1 ratio potentiometrically at (25 ± 0.1) °C.…”