1D-RISM study of glycine zwitterion hydration and ion-molecular complex formation in aqueous NaCl solutions

Structural aspects of the hydration of glycine zwitterion (Gly-ZW) in NaCl(aq) were studied over a wide concentration range of NaCl (c = 0-5 M) with the 1D-RISM integral equation method. Analysis of the structural data revealed that increasing salt concentration leads only to minor changes in hydration structure of Gly-ZW with the maximum effect occurring for the -NH3+ and -COO- groups where the number of H-bonds is decreased. On the other hand, increasing salt concentration stimulates the formation of ion-molecular complexes like (-NH3+:Cl-)(aq) and (-COO-:Na+)(aq). On the basis of the obtained data a structural mechanism for this process is suggested. (C) 2012 Elsevier B.V. All rights reserved.