Encapsulation of ciprofloxacin, sparfloxacin, and ofloxacin drugs with α- and β-cyclodextrins: spectral and molecular modelling studies

<div><p></p><p>Inclusion complexation of ciprofloxacin (CIP), sparfloxacin (SPA), and ofloxacin (OFL) drugs with α-CD and β-CD was studied by UV-visible, fluorescence, time-resolved fluorescence, Fourier transform infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance (¹HNMR), scanning electron microscopy (SEM), and molecular modelling techniques. Changes in the absorbance and fluorescence intensities and fluorescence lifetime of the drugs in the cyclodextrin (CD) solutions suggest the formation of inclusion complexes. Carbonyl stretching frequency moved to higher wave numbers and broadening of the N–H stretching band indicated the formation of inclusion complex. Cyclohexane ring protons of the drugs show remarkable upfield or downfield shift in the ¹HNMR spectrum, indicating that the cyclohexane part of the guest molecule is entrapped inside CD cavities. SEM images of CIP/CD, SPA/CD, and OFL/CD complexes have a crystal structure with different morphology from the isolated CIP, SPA, OFL, and CDs. Investigations of the energetic, thermodynamic, and electronic properties of parametric model number 3 computational calculations confirmed the stability of the inclusion complex.</p></div

Excimer emission of caffeine with α- and β-cyclodextrins: spectral and molecular modelling studies

<p>Excimer emission of caffeine with α-CD and β-CD were studied by UV-visible, fluorescence, time-resolved fluorescence, FTIR, ¹H NMR and molecular modelling techniques. Changes in the absorbance and fluorescence and lifetime of the caffeine with cyclodextrin (CD) solutions indicate (i) caffeine shows dual emission in the CD solutions, (ii) normal emission originates from a monomer and the longer wavelength emission is due to excimer and (iii) in both CDs caffeine forms 1:2 inclusion complex. Carbonyl stretching frequency moved to higher wave numbers and broadening of the N–H stretching band indicated the formation of inclusion complex. The resonance of the methyl protons of caffeine show remarkable upfield or downfield shift in the ¹H NMR, which indicates imidazole ring of the caffeine entrapped in the CD cavities. Investigations of energetic, thermodynamic and electronic properties of PM3 computational calculations confirmed the stability of the inclusion complex.</p