COMPLEX-FORMATION OF NITROBENZOIC ACIDS AND SOME NAPHTHALENE DERIVATIVES WITH BETA-CYCLODEXTRIN

Host-guest complexation of benzoic acid, its nitro-derivatives, 1- and 2-naphthols and 1- and 2-naphthylamines with beta-cyclodextrin have been investigated by a spectrophotometric method. Formation constants for both the conjugate acid and base forms have been determined. Only in the case of 4-nitrobenzoic acid, is a more stable complex formed with the ionic species, compared with the undissociated one, supporting the assumption that resonance charge delocalisation and London dispersion interactions are responsible for their stability. With naphthalene derivatives, the 2-isomers give more stable complexes indicating deeper penetration into the cyclodextrin cavity.