A cyclic porphyrin trimer as a receptor for fullerenes.

A cyclic porphyrin trimer has been synthesized which has a high affinity for fullerenes. It forms 1:1 complexes with C(60) and C(70) with association constants of 2 x 10(6) and 2 x 10(8) M(-1), respectively, in toluene. Its affinities for C(86) and La@C(82) are too strong to measure by fluorescence titration. The solvent dependence of the association constants shows that solvation of both the guest and the host influence the binding strength.