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exTTF as a Building Block for Fullerene Receptors. Unexpected Solvent-Dependent Positive Homotropic Cooperativity

2006; American Chemical Society; Volume: 128; Issue: 22 Linguagem: Inglês

10.1021/ja0621389

1943-2984

Emilio M. Pérez, Luis Sánchez, Gustavo Fernández, Nazario Martı́n,

Synthesis and Properties of Aromatic Compounds

The first exTTF-based receptor for molecular recognition of fullerene is described. Unexpectedly, the receptor shows completely different binding modes in chlorobenzene and CHCl3/CS2 mixtures. In the aromatic solvent, the receptor binds C60 in a noncooperative fashion (nH = 1) with a Kassoc = (2.98 +/- 0.12) x 103 M-1, whereas in CHCl3/CS2 mixtures, it shows a marked positive homotropic cooperative effect (nH = 2.7) toward binding of C60, with an apparent binding constant of (3.56 +/- 0.16) x 103 M-1. The unique solvent-switchable behavior of our receptor might find use in the controlled self-assembly of exTTF-C60 donor-acceptor ensembles.