Structural characterization of cyclodextrins: from inclusion complexes to Metal-Organic Frameworks (MOFs)

Cyclodextrins (CD) are cyclic oligosaccharides composed of six to more than sixty glucose units. α-CD, β-CD and γ-CD are well known CD consisting of 6, 7 and 8 glycopyranose units, respectively, that are torus-like rings built up from glycopyranose units. The secondary hydroxyl groups are situated on one of the two edges of the ring, whereas all the primary ones are placed on the other edge. The ring is a conical cylinder, which is frequently characterized as a doughnut or wreath shaped truncated cone. The cavity is lined with hydrogen atoms and glycosidic oxygen bridges, respectively. The primary and secondary hydroxyls on the outside of the cyclodextrins make cyclodextrins water-soluble. The cavity of the cyclodextrin consists of a ring of C-H groups, a ring of glycosidic oxygen atoms and again a ring of C-H groups. This renders the interior of the cyclodextrin rings less polar. As a consequence, the hydrophilic sites which are outside of the torus enable CD to be soluble in water, whereas the apolar cavity site which provides a hydrophobic matrix, enables CD to form inclusion complex with a variety of hydrophobic guest molecules. In addition, CD contains repeating units of ‒OCCO‒ binding motif on both their primary and secondary faces. This makes CD able to form extended structures with metal cations of Group IA and IIA (MOFs). The main goal of this thesis was to design, prepare and characterize new crystal systems based on cyclodextrins properties in combination with: 1. Para aminobenzoic acid (pABA) as a drug model to study the effect of complexation phenomena on the solubility of drugs. Their structure and mode of interaction were characterized by combination a theoretical and experimental approaches. 2. Potassium hydroxide to prepare cyclodextrin Metal-Organic Frameworks (CD-MOFs) formed by coordinating the cyclodextrins to potassium cation. Consequently, taking the advantages of this interaction between cyclodextrin and alkali metal cation, formation of inclusion complexes as CD-MOFs drug carrier was favored. 3. Aegelinol, a natural product, for analytical purposes to determine the absolute configuration of this compound by formation of an inclusion complex with a host of known chirality (cyclodextrins consists of several optically active D-glucose units). This should allow direct determination of the absolute configuration of the guest (aegelinol).(DOCSC02) -- FUNDP, 201