An oxacalix[2]arene[2]pyrimidine-bis(Zn-porphyrin) tweezer as a selective receptor towards fullerene C70

An oxacalix[2]arene[2]pyrimidine-bis(ZnII-porphyrin) conjugate was readily prepared via nucleophilic aromatic substitution of a phenolic AB3-Zn-porphyrin on the upper rim of a (1,3-alternate) 5,17-bis(methylsulfonyl)oxacalix[4]arene precursor. Efficient 1:1 complex formation between the ‘jaws’ bisporphyrin tweezer and fullerene C70 was evidenced by 1H NMR titrations (K = 3.0 × 104 M−1), while no detectable complexation could be observed with C60. On the other hand, an analogous oxacalix[4]arene-bis(Cu-corrole) conjugate did not show any measurable (C60 or C70) fullerene binding.