Supramolecular fullerene/porphyrin interactions: A rational approach towards charge transfer absorption and emission analyzed by electronic coupling theory

Solution state electronic (UV-Vis) and fluorescence spectra of the electron donor-acceptor complexes of 5,10,15,20-tetrakis(octadecyloxyphenyl)-21H,23H-porphyrin (TP) with [60]- and [70]fullerenes have been investigated in chloroform medium. Lifetimes of 0.5 ns and 0.85 ns are found for [60]fullerene/TP and [70]fullerene/TP complexes, respectively. The donor-acceptor electronic coupling (V) for the above two complexes have been estimated by two independent methods resulting in a relatively large value of ≈ 2−4 × 103 cm− 1, i.e., between 5000 and 2500 nm, which is resulted due to the close proximity of the porphyrin and fullerenes molecules. Electronic coupling element determined by absorption spectrophotometric method corroborates fairly well with those obtained from emission measurements. [70]fullerene/TP complex is shown to exhibit higher value of electronic transition moment.