Complexation of fluorenone and xanthone to cyclodextrins: Comparison of theoretical and experimental studies

The structural aspects for the complexation of xanthone and fluorenone to a lpha- as well as beta-cyclodextrins (CDxs) were explored by combining absor ption, fluorescence, and induced circular dichroism studies with theoretica l calculations of the optimized structures for the ketone-CDx complexes and their predicted ICD spectra, Detailed information on the similarities and differences for the complexes of these ketones with CDxs was obtained. For both CDxs, the ketones are bound to the rim of the cavity, and deeper penet ration is observed for the complexes with beta-CDx. In addition, a 1:2 comp lex involving alpha-CDx was only observed in the case of fluorenone. Althou gh the two ketones have similar structures, their molecular recognition pro perties and the resulting structures of the CDx complexes show distinct dif ferences.