Dual-Tweezer Behavior of an Octapodal Pyrene Porphyrin-Based System as a Host for Fullerenes

The incorporation of eight pyrene units in a single porphyrin core exhibits a great synergistic effect, resulting in high affinity toward C-60 and C-70. This octapyrene porphyrin is easily accessible by a straightforward two-step synthetic approach that involves an octuple Suzuki reaction. The new supramolecular platform can present single- or double-tweezer fullerene hosting behavior. The switch from double- to single-tweezer behavior is triggered by the simple coordination of Zn2+ to the porphyrin. Both the octapyrene porphyrin 2HPOP and its zinc metalloporphyrin analogue ZnPOP show very high affinity for C-60 and C-70, while simultaneously allowing the discrimination of C-70 over C-60 in a C-60/C-70 mixture. The use of 2HPOP and ZnPOP for the enrichment of real fullerene mixtures is also demonstrated.