Molecular programming of organogelators which can accept [60]fullerene by encapsulation

New porphyrin-based gelators bearing eight hydrogen-bond-forming amide groups at their periphery were synthesized. They acted as versatile gelators for aromatic solvents. SEM and TEM observations and X-ray crystallographic analysis established that they tend to aggregate into a two-dimensional sheet-like structure utilizing the intermolecular hydrogen-bonding interaction. In this structure the porphyrin-porphyrin pi-pi stacking interaction is not involved because of the energetically-predominant hydrogen-bonding interactions, keeping the space distance of 12.9 angstrom. Very interestingly, when C-60 was added, the morphology was transformed to a one-dimensional fibrous structure, which can enjoy a porphyrin-C-60-porphyrin interaction. This multicapsular structure having porphyrin-based compartments for hosting C60 was further characterized by XRD, EPR of a Cu(II) analogue, and the theoretical calculation. Thus, this paper presents a new concept, 'molecular recognition in gel', which is effective for the weak host-guest interaction. (c) 2005 Elsevier Ltd. All fights reserved.