A supramolecular oscillator composed of carbon nanocluster C(120) and a rhodium(III) porphyrin cyclic dimer

A rhodium(III) porphyrin cyclic dimer (1) included carbon nanocluster C120 (2) to form a pi-electronic supramolecular complex (1 superset2), in which 2 oscillated back and forth within its cavity. Spectroscopic titration of 1 with 2 and line shape analysis on variable-temperature 1H NMR spectral profiles of 1 superset2 and reference inclusion complexes in toluene-d8, chlorobenzene-d5, and dichlorobenzene-d4 indicated that the association constant (Kassoc) of 1 superset2 and oscillation activity of included 2 are both larger as the affinity of the solvent toward fullerenes is smaller. The DeltaS values for the oscillation were all positive, indicating that the oscillation of 2 involves desolvation of a protruding C60 moiety of included 2 from the host cavity.