Volumetric and acoustic methods for investigating molecular interactions of antibiotic drug doxycycline hyclate in water and in aqueous solution of sodium chloride and potassium chloride at different temperatures (293.15–313.15) K

Abstract

The solution properties of antibiotic drug Doxycycline Hyclate (DH) were investigated to explore molecular interactions with aqueous NaCl and KCl solutions around their physiological cell concentrations at different temperatures. Apparent molar properties i.e. apparent molar volume (ΦV) and apparent molar isentropic compression (ΦK) for DH within the concentration range (0.0020–0.0140) mol·kg−1 in water and in (0.005, 0.012 and 0.140) mol·kg−1 aqueous NaCl and KCl solutions were calculated from experimentally measured densities (ρ) and Ultrasonic speed (u) values at T = (293.15, 298.15, 303.15, 308.15 and 313.15) K temperatures and at P = 0.1 MPa pressure. The data of apparent molar properties were utilised to obtain various derived parameters such as limiting apparent molar volume, (Φvo), limiting apparent molar isentropic compression, (ΦKo), limiting apparent molar volume of transfer, ∆ΦVO, limiting apparent molar isentropic compression of transfer, ∆ΦKO, limiting apparent molar expansibility, ΦEo, and thermal expansion coefficient, α. The structure making/breaking ability of DH in aqueous NaCl and KCl were determined on the basis of Hepler's Equation i.e. on the basis of sign of (d2ΦVOdT2)P. The results obtained from all these thermodynamic parameters were discussed in terms of solute-solute and solute-solvent interactions in these systems. The volumetric, compressibility and acoustic data suggests the existence of strong solute-solvent interactions in the studied systems.