Excimer formation and intramolecular self-complexation of double-armed γ-cyclodextrin

Circular dichroism and fluorescence studies of γ-cyclodextrin bearing two naphthyl moieties (1) suggest that 1 exists as two intramolecular self-complexation forms in water-rich solutions with one or two of the naphthyl moieties included in its cavity. Upon addition of (−)-borneol as a guest, 1 forms a 1 : 1 host–guest complex, exhibiting slightly diminished excimer and circular dichroism bands. Ethylene glycol converts the intramolecular complexes into a relaxed form, in which two naphthyl moieties dangle outside the cavity. (Remark: Graphics omitted.)