Intermolecular interactions of α-amino acids and glycyl dipeptides with the drug domiphen bromide in aqueous solutions analyzed by volumetric and UV-vis spectroscopy methods

The interactions of four alpha-amino acids and three glycyl dipeptides with drug domiphen bromide (DB) as the function of temperature and DB molality have been investigated by combination of volumetric and UV-vis spectroscopy methods. The standard partial molar volume (V-2,V-phi degrees), standard partial molar transfer volumes (Delta V-t(o)), hydration number (n(H)), partial molar expansibility (E-phi degrees) and Hepler's factor (partial derivative V-2(2,phi)degrees/partial derivative T-2)(p) are calculated from the density data. The above parameters are used to interpret the solute-solvent interactions in ternary systems. The dependence of these parameters upon concentration, temperature and hydrocarbon chain length of the amino acids/dipeptides clearly suggest the roles of amino acids/dipeptides and domiphen bromide in solute-solvent interactions. Group contributions of amino acids/dipeptides to the standard partial molar volume were determined. For the studied glycyl dipeptides standard partial molar volume can be expressed by those of the corresponding amino acids in terms of an additivity scheme. The absorption spectra have also been recorded for present mixtures with the help of UV-vis spectrophotometer. The binding constant between amino acids/dipeptides and domiphen bromide was determined. (C) 2016 Elsevier Ltd.