Thermodynamic study of inclusion complexes of zaleplon with natural and modified cyclodextrins

Abstract

The thermodynamics and stoichiometry of zaleplon (ZAL) complexation with different cyclodextrin derivatives [b-CD, hydroxypropyl-b-cyclodextrin (HP-b-CD), randomly methylated-b-cyclodextrin (RAMEB), sulphobutylether-b-cyclodextrin (SBE-b-CD)] in aqueous solution was studied by spectrofluorimetry and 1 H NMR spectroscopy in order to obtain a more general understanding of the driving forces behind the inclusion phenomena. Job's plot derived from the NMR spectral data and statistical analysis of spectrofluorimetric titration data confirmed the formation of equimolar complexes in all systems tested, excluding the possibility of higher order complex formation. Furthermore, thermodynamic parameters obtained by both techniques gave similar and negative values of DG°for all complexes, indicating spontaneous inclusion of drug into CDs. From a thermodynamic point of view, two types of inclusions were determined. One is enthalpy driven ZAL complexation with b-CD, HP-b-CD and RAMEB, while the other is entropy driven complexation observed in the case of SBE-b-CD. The mechanisms behind each type of inclusion were discussed in detail.

Preparation of β-Cyclodextrin Polymer by Inverse-Phase Suspension Polymerization and its Capability for Phenol Removal

“…It is known that β-CD and substrates can form host-guest complex. This complexation depends on the size, shape and hydrophobicity of the guest molecule [12][13][14][15]. The adsorption capacity of EPI-CD polymer to phenol was further investigated.…”

α-Mangostin/γ-Cyclodextrin Inclusion Complex: Formation and Thermodynamic Study

“…The structure of α-M, γ-CD, α-M/γ-CD PM and α-M/γ-CD CX were analyzed using NMR spectrometry 500 Hz JEOL, JNM ECA 500 [ 19 , 27 ].…”

Ratiometric colorimetric detection of fluoride ions using a schiff base sensor: enhancing selectivity and sensitivity for naked-eye analysis

“…2(ii)). 30,31 The stoichiometry of F − ion complexation with the receptor was determined by the Benesi-Hildebrand plot method in DMSO (Fig. S4 †).…”