Supramolecular interaction of gemifloxacin and hydroxyl propyl β-cyclodextrin spectroscopic characterization, molecular modeling and analytical application

•Solid inclusion complex of GFX and HP-β-CD was prepared for the first time.•UV–visible, FTIR, NMR, and ESI-MS were used to investigate the inclusion complex.•The interaction between GFX and HPβ-CD was studied using molecular modeling.•A novel spectrofluorometric method was established for the determination of GFX.

The solid inclusion complex of gemifloxacin (GFX) and hydroxyl propyl β-cyclodextrin (HPβ-CD) was prepared and examined by UV–visible, FTIR, NMR, electrospray ionization mass spectrometry (ESI-MS) and fluorescence spectroscopy. The formation of inclusion complex has been confirmed on the basis of changes of spectroscopic properties. Further the interaction between GFX and HPβ-CD was studied using molecular modeling approaches. The results showed that HPβCD reacted with GFX to form a 1:1 host–guest inclusion complex. Based on the enhancement of the fluorescence intensity of GFX produced through complex formation, a simple, accurate, rapid and highly sensitive spectrofluorometric method for the determination of GFX in pharmaceutical formulation was developed. The linear relationships between the intensity and GFX concentration was obtained in the concentration range of 20–140 ng/mL with good correlation coefficients (0.9997). The limit of detection (LOD) was found to be 4 ng/mL. The proposed method was successfully applied to the analysis of GFX in pharmaceutical preparation.

Graphical abstractAbsorbance spectra (1) HP-β-CD, (2) GFX and (3) GFX-HP-β-CD inclusion complex, concentration of GFX 5 μg/mL, HP-β-CD 2 × 10−4 M, at room temperature, time 15 min, pH 3.0.Figure optionsDownload full-size imageDownload as PowerPoint slide