H. Hammud, Shawky El Shazly, G. Sonji
May 5, 2015
Citations
1
Influential Citations
4
Citations
Journal
Journal of Molecular Structure
Abstract
Abstract The ligands 3-(adenine-9-yl)propionic acid (AA) and 3-(thymine-1-yl)propionic acid (TA) were prepared by N9-alkylation of adenine and N1-alkylation of thymine with ethylacrylate in presence of a base catalyst, followed by acid hydrolysis of the formed ethyl esters to give the corresponding propionic acid derivatives. The products were characterized by spectral methods (FTIR, 1 H NMR and 13 C NMR), which confirm their structures. The dissociation constants of ligands, were potentiometrically determined in 0.3 M KCl at 20–50 °C temperature range. The work was extended to study complexation behavior of AA and TA with various biologically important divalent metal ions (Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Mn 2+ and Pb 2+ ) in 50% v/v water–ethanol medium at four different temperatures, keeping ionic strength constant (0.3 M KCl). The order of the stability constants of the formed complexes decreases in the sequence Cu 2+ > Pb 2+ > Zn 2+ > Ni 2+ > Co 2+ > Mn 2+ > Cd 2+ for both ligands. The effect of temperature was also studied and the corresponding thermodynamic functions (Δ G , Δ H , Δ S ) were derived and discussed. The formation of metal complexes has been found to be spontaneous, and the stability constants were dependant markedly on the basicity of the ligands.