Photophysical investigations on supramolecular interaction of a C60 derivative with free-base and metallo-phthalocyanines

The present paper reports the photophysical investigations on non-covalent interaction of a C60-derivative, namely, tert-butyl-(1,2-methanofullerene)-61-carboxylate (1) with H2– (H2–Pc) and Zn–phthalocyanine (Zn–Pc) in toluene medium. Well defined charge transfer (CT) absorption bands have been located in the ground state. Utilizing the CT absorption bands, various consequential physico-chemical parameters like oscillator strength, transition dipole moment, resonance energy, electronic coupling element and solvent reorganization energy, have been estimated for the complexes of 1 with phthalocyanines. The influence of 1 on the spectral characteristics of H2– and Zn–Pc are explained using a theoretical model that takes into account the interaction between electronic subsystems of 1 with the phthalocyanines (Pcs). Steady-state fluorescence experiment reveals large binding constants in the magnitude of 68,775 and 31,750 dm3 mol−1, for the 1:1 complexes of 1 with H2- and Zn–Pc, respectively. Density functional theoretical calculations reveal significant redistribution of charges between 1 and Pcs.