Molecular Interaction Studies of Doxycycline Hyclate in Aqueous Glycine or l-Alanine by Using Volumetric and Ultrasonic Parameters

Abstract

The intermolecular interactions of the antibiotic drug doxycycline hyclate in water, aqueous solutions of glycine and aqueous solutions of l-alanine were determined by using volumetric and acoustic methods at four different temperatures (305.15, 310.15, 315.15 and 320.15) K. The limiting partial molar volume $$(V_{\phi }^{{\text{o}}} )$$ , limiting standard partial molar volume of transfer $${(}\Delta_{{{\text{tr}}}} V_{\phi }^{{\text{o}}} )$$ , limiting partial molar adiabatic compressibility ( $$\kappa_{\phi ,s}^{{\text{o}}} )$$ and limiting partial molar adiabatic compressibility of transfer $${(}\Delta_{{{\text{tr}}}} \kappa_{\phi ,s}^{{\text{o}}} )$$ were calculated from the density and ultrasonic velocity data at different temperatures and the results suggest strong solute–solvent interactions. The caging effect of doxycycline hyclate in water and in aqueous solutions of glycine and aqueous solutions of l-alanine was studied using the positive values of $$\left( {E_{\phi }^{{\text{o}}} = \frac{{{\updelta }V_{\phi }^{{\text{o}}} }}{{{\updelta }T}}} \right)$$ . The structure making behavior of doxycycline hyclate in water, aqueous solutions of glycine and aqueous solutions of l-alanine was analyzed from the positive values of Hepler’s constant i.e. $$\left( {\frac{{{\updelta }^{2} V_{\phi }^{{\text{o}}} }}{{{\updelta }T^{2} }}} \right)$$ . The limiting isobaric thermal expansion coefficient $$\left( {\alpha^{{\text{o}}} { } = \frac{{E_{\phi }^{{\text{o}}} }}{{V_{\phi }^{{\text{o}}} }}} \right)$$ , intermolecular free length (Lf) and acoustic impedance (Z) of doxycycline hyclate in water, aqueous solutions of glycine and aqueous solutions of l-alanine were also calculated at the studied temperatures.