Cooperative C(60) binding to a porphyrin tetramer arranged around a p-terphenyl axis in 1:2 host-guest stoichiometry.

[structure: see text] Porphyrin tetramer 1 was newly designed and synthesized to construct a novel cooperative [60]fullerene (C(60)) binding system. Compound 1 has a p-terphenyl axis, which is expected to act as a scaffold for a guest-binding information transducer. In toluene, 1 can bind 2 equiv of C(60) to produce a 1:2 1/C(60) complex with association constants of 5800 M(-1) (K(1)) and 2000 M(-1) (K(2)). These values are significantly greater than those for control porphyrin dimers such as 2 and 3.