LAUSR

Abstract The interactions of third generation fluoroquinolone antibiotic drug Levofloxacin hemihydrate (LFH) with the naturally occurring polyol i.e. sorbitol as a function of temperature have been investigated by volumetric, acoustic and conductance methods. Densities, speeds of sound and conductance values of LFH (0.001–0.01 mol·kg−1) in water and aqueous sorbitol (0.002, 0.004 and 0.006 mol·kg−1) have been measured at different temperatures (300.15, 305.15, 310.15 and 315.15 K). The experimental density data was used to calculate apparent molar volume (ΦV), limiting apparent molar volume (ΦVo), Masson's coefficient (SV), partial molar expansibilities (ΦE0), transfer volume ΔtrΦVo and Hepler's constant ∂ 2 Φ V o ∂ T 2 . From speed of sound data parameters like isentropic compression (βS), intermolecular free length (Lf), specific acoustic impedance (Z) and molar compressibility (W) were calculated. From conductance data specific conductance (Ҡ), molar conductance (Λm), limiting molar conductance (Λmo), Walden product (Λmoηo), dissociation constant (Kc) and activation energy (Ea) were calculated. The derived data has been discussed in terms of solute-solute and solute-solvent interactions. The positive values of ∂ 2 Φ V 0 ∂ T 2 and positive temperature coefficient of Walden product Λmoηo suggests that LFH acts as structure-maker in water and aqueous sorbitol systems.