Structural studies on inclusion compounds of beta-cyclodextrin with some substituted phenols

A detailed structural study of the inclusion compounds of some substituted phenols such as catechol, guaiacol, protocatechuic aldehyde, vanillin, caffeic acid, ferulic acid and eugenol with beta-cyclodextrin (beta CD) was tarried out by using UV-visible, fluorescence, H-1 and solid-state C-13 NMR spectroscopic and potentiometric investigations. Based on these studies guaiacol, catechol and eugenol were found to exhibit identical orientations - with the phenyl ring within the cavity and the hydroxyl and methoxyl groups projecting outside; protocatechuic aldehyde, caffeic acid, ferulic acid and vanillin display a different orientation - with the phenol part within the cavity and the aldehyde or carboxyl part projecting outside.