Novel fullerene receptors based on calixarene–porphyrin conjugates

Several different synthetic approaches enabling a direct covalent connection between the meso-position of porphyrin and the upper rim of calix[4]arene have been studied. The best results were obtained via condensation of an excess of pyrrole and p-methylbenzaldehyde with calix[4]arene-5,17-dialdehyde under BF3·Et2O catalysis in CHCl3. Subsequent oxidation of the intermediate porphyrinogen gave the corresponding bis-porphyrin–calixarene conjugate in 15% overall yield. The 1H NMR complexation study revealed the pronounced selectivity of the bis-porphyrin derivative towards C70 fullerene.