Thermodynamic parameters for the interaction of metal-nucleoside-amino acid systems

Abstract

Interaction of Cu(II), Ni(II), Zn(II) and Co(II) with cytidine, uridine and amino acids, viz., alanine, phenylalanine and tryptophan in a 1:1:1 ratio has been investigated at different temperatures. Thermodynamic parameters pertaining to the above interactions have been evaluated by means of temperature coefficient data. The overall negative contribution to the enthalpy can be ascribed to the formation of M-N bonds, while the positive entropy, from the charge neutralization of the secondary ligands. In the case of M(ll)-uridine-amino acid systems, the <img src='/image/spc_char/delta.gif' border=0><i>H</i>°_f and <img src='/image/spc_char/delta.gif' border=0>S°_f are comparable magnitude which indicates the absence of any additional contributions from the secondary ligands. This is being interpreted in terms of stacking interaction. Other quantities like <img src='/image/spc_char/delta.gif' border=0><img src='/image/spc_char/delta.gif' border=0><i>H</i>°_f and <img src='/image/spc_char/delta.gif' border=0><img src='/image/spc_char/delta.gif' border=0><i>S</i>°_f are also evaluated for a more comprehensive understanding of these interactions in solution.