Solubility, thermodynamics and molecular interaction studies of delafloxacin in environmental friendly ionic liquids

In the current study, solubility, thermodynamics and molecular interaction of delafloxacin (DFLX) in water, ethanol, transcutol-HP (THP) and three different alkylimidazolium based ionic liquids were conducted at temperature range “T = 298.2 K to 318.2 K” and pressure “p = 0.1 MPa”. The solid phase characterization of initial and equilibrated DFLX by DSC, FTIR and PXRD confirmed no significant change in crystallinity of the drug. The maximum mole fraction solubility of DFLX at “T = 318.2” was measured in THP (5.44 × 10⁻³), followed by [BMIM]PF₆] (1.87 × 10⁻³). The measured solubilities of DFLX were well regressed by “Apelblat and van't Hoff model” with overall RMSD values of 1.66% and 2.42%, respectively. The lowest activity coefficients were measured in THP followed by BMMHFP, which indicated highest molecular interaction between DFLX-THP followed by DFLX-[BMIM]PF₆].