Absorption spectroscopic study of the complexation of C70 with aniline and substituted anilines

Complexes of fullerene C-70 with aniline and various substituted anilines have been studied in CCl4 medium by electronic absorption spectroscopy. An absorption band due to a charge transfer (CT) transition is observed in the visible region. The experimental CT transition energies are well correlated (through Mulliken's equation) with the ionization potentials (I-D) of the series of anilines studied. From an analysis of this correlation, the electron affinity of C-70 has been found to be 2.28 eV. The degree of charge transfer in the ground state of the complexes has been found to be very low (0.2-0.3%). The experimentally determined formation constants of the complexes of C-70 with N-substituted anilines exhibit a very good linear free-energy relationship.