Complejos de inclusion de ciclodextrinas naturales y poli(b-ciclodextrina) con dibenzofuranos

Zusammenfassung

#TITULO: COMPLEJOS DE INCLUSIÓN DE CICLODEXTRINAS NATURALES Y POLI(B-CICLODEXTRINA) CON DIBENZOFURANOS #RESUMEN: The thesis describes the investigation of the complexes formed in solution between natural cyclodextrins and soluble polymers of b-CD with model substrates belonging to the series of the dioxins: dibenzofuran, dibenzofuran-2-ol, and 2-dibenzofuran carboxylic acid. All these dibenzofurans form inclusión complexes with b- and g-CD, being the former the macrocycle yielding the most stable adduct, always with a 1:1 stoichiometry. The wider g-CD can lodge two guests, producing stoichiometries that vary depending on the substrate. The compatibility in size between the nost and the guest is the determining factor in the stability. The spectral properties of the DBFs strongly depend on the nature of the guest, the macrocycle, and the pH. For the more soluble 2-dibenzofuran carboxylate, the topology of the complexes has been deduced with the aid of NMR-ROESY spectroscopy, combined with rigid docking and molecular dynamics strategies. According to fluorescence anisotropy results, soluble poly(b-cyclodextrins) crosslinked with epichlorohydrin improve the retention of neutral DBFs, irrespective of the molecular weight or microstructure of the polymer. The similarity in the spectral properties with those of natural CD complexes suggests a preferential inclusional interaction, reinforced by the extension of the cavity of the b-CD with the glyceryl linkers. Dynamic light scattering experiments show that natural CDs form large aggregates in water, held together by the hydroxyl groups of the macrocycles. This aggregation is especially persistent for the b-CD, although the contribution to the overall mass due to the aggregates is scarce and can be neglected for many practical purposes