Photophysical investigations on supramolecular interaction of a C 60 derivative with free-base and metallo-phthalocyanines

Abstract

The present paper reports the photophysical investigations on non-covalent interaction of a C 60-derivative, namely, tert-butyl-(1,2-methanofullerene)-61-carboxylate ( 1) with H 2– (H 2–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 H 2– 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 dm 3 mol −1, for the 1:1 complexes of 1 with H 2- and Zn–Pc, respectively. Density functional theoretical calculations reveal significant redistribution of charges between 1 and Pcs.