UV-Vis spectroscopic techniques in the study of the cyclodextrin inclusion complexes

In the field of host-guest chemistry, i.e. the chemistry of supramolecular species characterized by non covalent interactions, cyclodextrins (CyDs) represent one of the most important host systems. The natural ?-, ?- and ?-CyD consist of six, seven or eight D-glucopyranose residues, respectively, linked by ?-1,4 glycosidic bonds in a macrocyclic structure. These oligosaccharides are able to associate in their hydrophobic cavities an extremely large variety of molecular species, forming inclusion complexes, that revealed useful for widespread technological applications and scientific purposes (pharmaceutical, cosmetic, food science and technology, analytical and synthetic chemistry, drug delivery). A very important prerequisite of any application is the characterization of the inclusion complexes as new chemical entities. To this goal the properties of the guest molecule, which are modified by the interaction with the CyDmacrocycle, can be exploited. This lecture will focus on the spectroscopic properties ofCyD inclusion complexesof molecules in the UV-Vis region, with particular attention to drugs.The application of electronic absorption, fluorescence and circular dichroismfor the determination of stoichiometry, stability constants, ground state structure and excited state parameters will be illustrated.