Synthesis and structure of nitrogen bridged calix[5]- and -[10]-pyridines and their complexation with fullerenes

Azacalix[5] pyridine, a heteroatom bridged calixaromatic with an odd number of arene units, and azacalix[10] pyridine, a giant molecular belt, were selectively synthesized based on a 2 + 3 macrocyclic coupling strategy; both novel macrocyclic hosts formed strong 1 : 1 complexes with fullerenes C-60 and C-70 in a size-selectivemanner with association constants up to 1.3x10(5) +/-0.03 x 10(5) M-1.