Cationic shape-persistent macrocycles: the unexpected formation of a nano-size supramolecular dimer

Shape-persistent macrocycles with a rigid pyridyl core and a flexible oligo-alkyl corona aggregate to some extent in nonpolar solvents to form large (tubular) aggregates. To increase the assembling tendency, the intraannular pyridyl groups of the macrocycles were alkylated. Unexpectedly, the quarternized macrocycles show no tendency at all to form tubular micellar-like structures but form well-defined dimers, as determined by X-ray and dynamic light scattering.