GUEST-GUEST INTERACTIONS IN UREA INCLUSION-COMPOUNDS

Different types of urea inclusion compounds have been studied to test the importance of the molecular interactions between the guests. Exper imental evidence has been obtained from the EPR spectra of radicals de rived from guests by room temperature gamma-ray irradiation of the inc lusion compounds. The guest-guest intra-channel interactions are very important in the case of tridecanedioic and tetradecanedioic dicarboxy lic acid guests which give rise to strong intermolecular hydrogen bond ing between the carboxylic groups. It is found that the molecular conf ormation of the tetradecanedioic acid is strongly distorted to fit in the host channel dimensions. The interactions between guest molecules included in adjacent host channels have been modulated by varying the relative guest composition in a mixed nonadecan-10-one-nonadecane incl usion compound. It is shown that the molecular reorientation of the no nadecan-10-one guest becomes faster by increasing the nonadecane perce ntage as a consequence of the reduced inter-channel interactions.