Selective C70 Recognition by a Structurally Rigid Porphyrin-Carbazole Cavitand having a Smaller Cavity

The development of novel molecular receptors having strong noncovalent interactions with fullerenes is highly rewarded due to their wide applications in the separation of fullerenes. We report here two new co-facial porphyrin dimers that show the potential to bind fullerenes strongly. The most interesting observation is that both the open and closed forms of the receptors show similar binding affinities and show selectivity towards C70, even in the presence of a significant amount of C60. Thus, the binding ability in this case can be attributed mainly to the van der Waals interactions and residual flexibility of the host, rather than to the volume or geometry of the host cavity.