Acidity and complex formation studies of 3-(adenine-9-yl)-propionic and 3-(thymine-1-yl)-propionic acids in ethanol-water media

作者：Hammud Hassan H^*; El Shazly Shawky; Sonji Ghassan; Sonji Nada; Bouhadir Kamal H

来源：Journal of Molecular Structure, 2015, 1087: 33-40.

DOI：10.1016/j.molstruc.2015.01.009

• 3-(Adenine-9-yl)propionic acid
• 3-(Thymine-1-yl)propionic acid
• Potentiometric titration
• Acidity and stability constants

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, H-1 NMR and C-13 NMR), which confirm their structures. The dissociation constants of ligands, were potentiometrically determined in 0.3 M KCl at 20-50 degrees C temperature range. The work was extended to study complexation behavior of AA and TA with various biologically important divalent metal ions (Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Mn2+ and Pb2+) 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 Cu2+ > Pb2+ > Zn2+ > Ni2+ > Co2+ > Mn2+ > Cd2+ for both ligands. The effect of temperature was also studied and the corresponding thermodynamic functions (Delta G, Delta H, Delta 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.

• 出版日期2015-5-5