Alternating 2,6-/3,5-Substituted Pyridine-Acetylene Macrocycles: π‑Stacking Self-Assemblies Enhanced by Intermolecular Dipole–Dipole Interaction

Macrocyclic
compounds consisting of three 2,6-pyridylene and three
3,5-pyridylene units linked by acetylene bonds were synthesized by
a Sonogashira reaction. The X-ray structures showed π-stacked
pairs of two macrocycles, in which a 2,6-pyridylene unit of the one
molecule overlaps a 3,5-pyridylene of the other molecule because of
dipole–dipole interaction. Atomic force microscope (AFM) measurements
revealed fibril structures indicating the stacking of the rigid planar
macrocycles. Hydrogen-bonding ability of the macrocyclic inside was
demonstrated by the addition of octyl β-d-glucopyranoside.