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

Abstract

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.