Controlled arrangements of fullerenes within nano space of self-assembling porphyrins

In order to construct controlled arrangements of fullerenes, we have prepared cyclic porphyrin dimers (M₂-CPD, M=Ni, H₂), which include fullerenes with high affinities (K_assoc ≈ 10⁵ M^-1). These dimers have two self-assembling 4-pyridyl groups at the opposite meso positions. In crystals, inclusion complexes of C₆₀ and PCBM within the nickel dimer (C₆₀ ⊂ Ni₂-CPD and PCBM ⊂ Ni₂-CPD) result in a linear array of the fullerene molecules in the self-assembled porphyrin nanotube, which is formed by the stacking of the cyclic dimer through the non-classical hydrogen-bonding interactions between pyridyl nitrogens and pyrrole β C-H groups. In contrast, the inclusion complexes of C₆₀ and C₇₀ within the free-base dimer (C₆₀ ⊂ H₄-CPD and C₇₀ ⊂ H ₄-CPD) afford zigzag arrays of the fullerene molecules without the formation of nanotube structure. Owing to the well-controlled arrangement of C₆₀ above mentioned, C₆₀ ⊂ Ni₂-CPD and C₆₀ ⊂ H₄-CPD exhibit high electron mobility (∑μ > 0.1 cm²V^-1s^-1) along the array. Moreover, C₆₀ ⊂ H₄-CPD undergoes photoinduced electron transfer from the porphyrin to C₆₀ to produce a charge-separated state.