Octatetrayne-linked porphyrins: ‘stretched’ cyclic dimers and trimers with very spacious cavities

Syntheses are described for two octatetrayne-linked cyclic porphyrin oligomers with extremely spacious cavities. These hosts bind strongly to complementary multidentate guests. Thus, the octatetrayne-linked dimer binds bifunctional ligand bis(4-pyridyl)ethyne with an affinity of 7 × 106 dm3 mol–1, and the trimer binds the new ‘stretched’ trifunctional ligand 1,3,5-tris[(4-pyridyl)ethynyl]benzene with an affinity of 2 × 108 dm3 mol–1 in C2H2Cl4 at 30 °C.