Thermodynamic parameters for the association of natural and substituted -, -, and -cyclodextrins with acetylsalicylic acid, salicylic acid and ibuprofen have been determined by isothermal titration calorimetry. Analysis of the data shows that complexes form, all having 1:1 stoichiometry. The shapematching between the host and guest is the factor determining the values of the thermodynamic quantities. In the case of the smallest cyclodextrin interacting with acetylsalicylic acid and salicylic acid, the parameters indicate that hydrophobic interactions play the major role. Association occurs through the shallow inclusion of the benzene ring into the cavity. In the case of substituted -cyclodextrins, instead, inclusion of the benzene ring is deeper and the tight fitting of the guest molecule to the cavity makes the enthalpy and entropy to be both negative. Ibuprofen interacts through its isobutyl group: the values of the association constants are very high for -cyclodextrins as determined by the large and positive entropies due to the relaxation of water molecules from the cavity and the hydration spheres of the interacting substances. For all systems, a compensatory enthalpy–entropy relationship exists unless for those involving -cyclodextrins and ibuprofen.

Thermodynamics of inclusion complexes of natural and modified cyclodextrins with acetylsalicylic acid and ibuprofen in aqueous solution at 298K / Castronuovo, Giuseppina; Niccoli, Marcella. - In: THERMOCHIMICA ACTA. - ISSN 0040-6031. - 557:(2013), pp. 44-49. [10.1016/j.tca.2013.01.037]

Thermodynamics of inclusion complexes of natural and modified cyclodextrins with acetylsalicylic acid and ibuprofen in aqueous solution at 298K

CASTRONUOVO, GIUSEPPINA;NICCOLI, MARCELLA
2013

Abstract

Thermodynamic parameters for the association of natural and substituted -, -, and -cyclodextrins with acetylsalicylic acid, salicylic acid and ibuprofen have been determined by isothermal titration calorimetry. Analysis of the data shows that complexes form, all having 1:1 stoichiometry. The shapematching between the host and guest is the factor determining the values of the thermodynamic quantities. In the case of the smallest cyclodextrin interacting with acetylsalicylic acid and salicylic acid, the parameters indicate that hydrophobic interactions play the major role. Association occurs through the shallow inclusion of the benzene ring into the cavity. In the case of substituted -cyclodextrins, instead, inclusion of the benzene ring is deeper and the tight fitting of the guest molecule to the cavity makes the enthalpy and entropy to be both negative. Ibuprofen interacts through its isobutyl group: the values of the association constants are very high for -cyclodextrins as determined by the large and positive entropies due to the relaxation of water molecules from the cavity and the hydration spheres of the interacting substances. For all systems, a compensatory enthalpy–entropy relationship exists unless for those involving -cyclodextrins and ibuprofen.
2013
Thermodynamics of inclusion complexes of natural and modified cyclodextrins with acetylsalicylic acid and ibuprofen in aqueous solution at 298K / Castronuovo, Giuseppina; Niccoli, Marcella. - In: THERMOCHIMICA ACTA. - ISSN 0040-6031. - 557:(2013), pp. 44-49. [10.1016/j.tca.2013.01.037]
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/572457
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 24
  • ???jsp.display-item.citation.isi??? 22
social impact