An oxacalix[2]arene[2]pyrimidine-bis(Zn-porphyrin) tweezer as a selective receptor towards fullerene C-70

Abstract

An oxacalix[2]arene[2]pyrimidine-bis(Zn-II-porphyrin) conjugate was readily prepared via nucleophilic aromatic substitution of a phenolic AB(3)-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 C-70 was evidenced by H-1 NMR titrations (K = 3.0 x 10(4) M-1), while no detectable complexation could be observed with C-60. On the other hand, an analogous oxacalix[4]arene-bis(Cu-corrole) conjugate did not show any measurable (C-60 or C-70) fullerene binding. (C) 2010 Elsevier Ltd. All rights reserved.