π-electronic charge-transfer interactions in supramolecular complex formation between fullerenes and 5,10,15,20-tetrahexylporphyrin

UV-Vis spectral investigations on fullerenes/5,10,15,20-tetrahexylporphyrin (TP) supramolecular complexes are reported in CCl4 and CHCl3. An absorption band due to charge transfer (CT) transition is observed in the visible region. Vertical ionization potential of TP was determined from the CT transition energy. CT is very weak in these complexes as reflected from very low values of oscillator strengths and transition dipole strengths. All of the complexes are found to be stable with 1:1 stoichiometry. Thermodynamic parameters for the supramolecular complexes of TP with [60]- and [70]fullerenes are reported. The high formation constant value for the [60]fullerene/TP complex as compared to [70]fullerene/TP complex indicates selectivity of TP molecule towards [60]fullerene.