In the present paper, the vibrational dynamics of solid inclusion complexes of the nonsteroidal anti-inflammatory drug Ibuprofen (IBP), both in racemic and enantiomeric form, with native beta-cyclodextrin (beta-CD), and its substituted form methyl-beta-cyclodextrin (Me-beta-CD) has been investigated by using Fourier transform infrared spectroscopy in Attenuated Total Reflectance geometry (FTIR-ATR), in order to monitor the changes induced, as a consequence of complexation, on the vibrational spectrum of IBP, also emphasizing the effects of chiral discrimination. Quantum chemical calculations were performed on monomeric and dimeric structures of IBP, derived from symmetric hydrogen bonding of the two carboxylic groups, in order to unambiguously assign some characteristic IR bands in the IBP spectrum. The evolution in temperature from 250 to 340 K of the C=O stretching vibration allowed us to reveal an enthalpy-driven inclusion mechanism and to extract the thermodynamic parameter ΔH associated to the binding of IBP with beta-CDs in the solid phase. Me-BETA-CD has been shown to be the most effective carrier for IBP, with IBP enantiomers giving rise to more stable inclusion complexes with respect to the racemate.
Vibrational dynamics and chiral properties of racemate and pure enantiomers of Ibuprofen complexed in Cyclodextrins: state of art
CRUPI, Vincenza;MAJOLINO, Domenico;VENUTI, Valentina;
2013-01-01
Abstract
In the present paper, the vibrational dynamics of solid inclusion complexes of the nonsteroidal anti-inflammatory drug Ibuprofen (IBP), both in racemic and enantiomeric form, with native beta-cyclodextrin (beta-CD), and its substituted form methyl-beta-cyclodextrin (Me-beta-CD) has been investigated by using Fourier transform infrared spectroscopy in Attenuated Total Reflectance geometry (FTIR-ATR), in order to monitor the changes induced, as a consequence of complexation, on the vibrational spectrum of IBP, also emphasizing the effects of chiral discrimination. Quantum chemical calculations were performed on monomeric and dimeric structures of IBP, derived from symmetric hydrogen bonding of the two carboxylic groups, in order to unambiguously assign some characteristic IR bands in the IBP spectrum. The evolution in temperature from 250 to 340 K of the C=O stretching vibration allowed us to reveal an enthalpy-driven inclusion mechanism and to extract the thermodynamic parameter ΔH associated to the binding of IBP with beta-CDs in the solid phase. Me-BETA-CD has been shown to be the most effective carrier for IBP, with IBP enantiomers giving rise to more stable inclusion complexes with respect to the racemate.Pubblicazioni consigliate
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