The role of additives on the interaction behavior of levofloxacin hemihydrate with crown ether: UV–visible spectroscopic and DFT techniques

Abstract

The levofloxacin hemihydrate (LH); a third generation floroquinolone antibiotic drug works against bacteria by killing bacteria or stopping their growth. But it has some side effects which may be reduced by a better drug delivery system. So, the interactions between crown ether (CE), benzo-18-crown-6 (B18C6), and LH molecule have been studied using UV spectrometry at different concentrations of both B18C6 and LH as well as varying conditions like temperature (303.15–318.5 K with 5 K interval), pH, and nature of solvents (aq. electrolytes, and alcohols media). The UV–visible spectra reflected evidence for the B18C6-LH complexation through a remarkable λmax value shifting. The stability of the complex formation was known from the binding constant (Kb) value which has been computed from Benesi-Hildebrand plot. The ease of complex formation was supported by various thermodynamic parameters. A high negative value of ΔG0 indicates that the complexation was a thermodynamically spontaneous process. Again, a negative value of ΔH0 and a positive value of ΔS0 indicate that the binding process was an exothermic and enthalpy driven phenomenon. The density function theory (DFT) studies also reveal the presence of strong interaction amongst the B18C6 and LH. The reason behind this study is to investigate whether B18C6 can play any role in drug delivery due to its amphiphilic nature or not.