Characterization of solid complexes between aromatic ketones and beta-cyclodextrin using diffuse reflectance infrared Fourier transform spectroscopy

The diffuse reflectance infrared Fourier transform spectra of solid complex es 1-indanone/beta -cyclodextrin (beta -CD), 2-indanone/beta -CD, 1'-aceton aphthone/beta -CD, and 2'-acetonaphthone/beta -CD exhibit a series of very important effects induced by complexation. For the complexes 1-indanone/bet a -CD, 2-indanone/beta -CD, and 2'-acetonaphthone/beta -CD, a dramatic decr ease on the intensity of the band assigned to the water deformation mode wa s observed, showing that these probes are deeply included in the cyclodextr in cavity, displacing the crystallization water. Hydrogen bonding interacti ons involving the ketone carbonyl and the hydroxyl groups of beta -CD are r esponsible for the stabilization of the complexes 1-indanone/beta -CD and 2 '-acetonaphthone/beta -CD In what concerns the complexes 2-indanone/beta -C D and 1'-acetonaphthone/beta -CD, it is suggested that they are stabilized only by London interactions between the aromatic ring and the cyclodextrin cavity.