A supramolecular porphyrin–ferrocene–fullerene triad

Abstract

A ferrocene (Fc) functionalized bis-porphyrin molecule has been synthesized as a host for fullerenes. The porphyrin used in these studies was prepared using a mixed boronic acid Suzuki reaction, which gives A₂BC type porphyrins in high yield. The bis-porphyrin was characterized through ¹H NMR spectroscopy, high-resolution mass spectroscopy and analyzed via molecular modeling studies. Complexation experiments with fullerenes utilizing both UV-visible and fluorescence spectroscopy demonstrated formation of strong complexes for the bis-porphyrin. A short-lived charge transfer luminescent state is detected for the fullerene adducts. Owing to the tight coupling of the fullerene and porphyrin partners, the host-appended Fc moiety does not show a direct role in the pattern of photoinduced processes upon excitation of either chromophores, but causes blue-shift of the NIR CT luminescence compared to previously investigated systems without appended fragments. Instead, the active role of Fc in photoinduced processes is observed for the guest molecules alone, where photoinduced energy transfer from the porphyrin to the ferrocene occurs.