Ultrasonic and viscometric study of molecular interactions of antibiotic doxycycline hycalte

Abstract

Dilute solution viscometric (DSV) and ultrasonic techniques are employed to investigate the aqueous solutions of antibiotic doxycycline hyclate for different molar concentrations around the physiological temperatures. The viscometric Huggin’s plots and interaction parameter identify the existence of dimerization of doxycycline at 303.15 K and the dominance of solute-solvent interaction at higher temperatures. The ultrasonic velocity and the thermo acoustic parameters confirm the results obtained by DSV. For further confirmation of dimerization, the stacking parameter (D) was obtained through the Hemme’s isodesmic model. The values of ‘D claim the dimerization of doxycycline at ambient temperature and dissociation among the antibiotic molecules at 308.15 and 313.15 K. The ultrasonic velocity derivative limiting slope (A) claims solute-solute and solute-solvent interactions at ambient and elevated temperatures, respectively. The stacking constant (K) decreases with increase of temperature. The structure change of solvent is discussed.