Interaction of pyromellitic diimide derivatives with beta-cyclodextrin and anthracene-appended beta-cyclodextrin: rim binding vs inclusion complexation.

Complex formation of pyromellitic diimide derivatives with beta-cyclodextrin and anthracene-appended beta-cyclodextrin was studied with use of induced circular dichroism and 1H NMR spectroscopies. It is revealed that pyromellitic diimides form rim-binding type complexes with beta-CD and in these complexes the pyromellitic diimides lie just outside of the narrow rim of the CD. With anthracene-appended beta-CD the pyromellitic diimides form true inclusion complexes. Implications of the formation of rim-binding type complexes are also discussed.