Abstract
Inclusion complexes of R-ketoprofen and S-ketoprofen enantiomers with β-cyclodextrin (β-CD) in aqueous solution were studied using various spectroscopic techniques such as Raman, FTIR, UV and fluorescence. The different relative intensities and characteristic band shifts of the two enantiomers from Raman spectra suggests different interaction when complexed with β-CD. Raman experiments revealed a noticeable diminishing of the CC vibration and ring deformation, which indicate the embedding of ketoprofen inside the β-CD cavity. It's revealed that distinct differences between R- and S-ketoprofen in the presence of β-CD at neutral pH. The stoichiometry ratio and binding constant of the inclusion complexes were calculated using Benesi–Hildebrand plot. Both enantiomers showed stoichiometry ratio of 1:1 inclusion complex with β-CD. The binding constant of R-ketoprofen (4088 M−1) is higher than S-ketoprofen (2547 M−1). These values indicated that β-CD formed inclusion complexes more preferentially with R-ketoprofen than S-ketoprofen. Results demonstrated that β-CD can be used as a promising chiral selector for ketoprofen enantiomers.
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•Guest-host inclusion complexation of S- and R-ketoprofen enantiomers and β-cyclodextrin (β-CD) was examined using Raman, FT-IR, UV and fluorescence.•Only R-ketoprofen solution changed from colorless to cloudy appearance with the addition of β-CD and can be observed with the naked eyes.•Raman experiments revealed a noticeable diminishing of the CC vibration and ring deformation, which indicate the embedding of ketoprofen inside the β-CD cavity.•β-CD shows chiral discrimination of ketoprofen enantiomers at neutral pH.•The obtained values of binding constants and negative ΔG indicate the thermodynamic favorability of both ketoprofen enantiomers but the higher values for R-ketoprofen suggests preference of β-CD inclusion complexation with R-ketoprofen.