Photochemistry of benzophenone-cyclodextrin inclusion complexes

Abstract

The photochemistry of benzophenone aqueous solutions in the presence of cyclodextrins (CDx) has been studied by stationary and pulsed techniques. Quenching of the phosphorescence is the consequence of hydrogen abstraction following the inclusion in the cyclodextrin cavity of the triplet benzophenone. The H-abstraction process has close analogies with the same reaction in micelles. Radical pair decay is controlled by the dimensions of the CDx cavity: intersystem crossing prevails in the presence of ß-CDx, radical exit in the presence of a-and -CDx. The fate of the escaped radical also depends on the cavity dimensions, as revealed by the photoreduction quantum yields.

Spontaneous association of hydrophobized dextran and poly-β-cyclodextrin into nanoassemblies.

“…In this study, the interfacial behaviour of MD was analysed when alone in the solution and after injection of native CD molecules, and pβCD. MD was then mixed to a drug molecule, benzophenone, chosen for its hydrophobicity and appropriate molecular weight for inclusion complex formation with β-CDs [52,53]. Both native β-CD and pβCD did not show any surface property: the measured surface tensions of their solutions (1 < [pβCD] < 5 g/L) varied in the range of 71.6-72.0 mN/m only.…”

PHOTOCHEMISTRY IN A CYCLODEXTRIN CAVITY. PRIMARY PROCESSES IN THE PHOTOREDUCTION OF 3‐ and 4‐BENZOYLPYRIDINE STUDIED BY LASER FLASH‐PHOTOLYSIS*

“…The laser flash-photolysis equipment has been already described (Monti et a/., 1988). The laser was focused on a rectangular area, 3 m m high and 10 m m wide, of the cell containing the sample and the first 2 m m were analyzed in a right angle geometry.…”

“…We have recently investigated the photoreduction of benzophenone (BP) included in CDx cavity (Monti et al 1988 cavity size, the fate of the primary radical pair. A direct influence on the relative yield of the cage recombination and escape processes of the two radical fragments is thus achieved.…”

Fluorescence study of tetracaine–cyclodextrin inclusion complexes

“…4,5 The formation of inclusion complex means that compatibility is reached between the host and the guest in terms of the polarity and stereochemistry; in this process, the guest molecule experiences a non-polar environment and possesses a decreased freedom for bulk and intramolecular rotations, in the rigid nonpolar CD cavity. This ability of CDs to accommodate guest molecules of the appropriate size in their cavities has been utilized to control photophysical and photochemical properties 6,7 or chemical reactivity 8,9 of molecules. The restricted shape and size and the hydrophobic nature of the cavities of CDs offer the opportunity to carry out selective phototransformations and to investigate specific aspects of photochemical mechanisms.…”