A new metalloporphyrin dimer: Effective and selective molecular tweezers for fullerenes

The present Letter introduces a new type of metalloporphyrin dimer, 1, to examine its optical absorption and luminescence in complexation with C60 and C70 in toluene medium. Large binding constants (K) in the magnitude of ∼3 × 104 and ∼2 × 105 dm3 mol−1 were obtained for the 1:1 complexes of 1 with C60 and C70, respectively. Values of K suggest that 1 serves as an effective and selective tweezers to capture C70 in preference to C60. Molecular mechanics and semi-empirical PM3 calculations extend a good support in interpreting the stabilization energies and electronic structures for the C60 and C70 complexes of 1.