One-pot formation of large macrocycles with modifiable peripheries and internal cavities.

The shape of things to come: Aromatic oligohydrazide macrocycles with planar backbones enforced by three-center hydrogen bonds are formed in high yield from monomeric diacid chlorides and dihydrazides. Macrocycles consisting of six meta-linked pyridine and benzene residues have an internal cavity of about 10 A diameter, while those with alternating meta- and para-linked benzene residues are larger and contain multiple convergent sites (see picture).