Hollow and Solid Spheres Assembled from Functionalized Macrocycles Containing Adamantane

An
adamantane-based macrocycle possessing eight hydroxyl groups
(1) was synthesized, in which the macrocyclic framework
comprises two disubstituted adamantane molecules bearing phenyl derivatives
connected to two biphenylene spacers by oxygen atoms. Furthermore,
functionalized macrocycles containing methyl (2) and
methoxycarbonylmethyl (3) groups were prepared. From
the X-ray crystallographic analysis, the backbone of the macrocycles
in all crystals had a nearly hexagonal shape with a cavity and these
macrocycles could be arranged into different tubular structures dependent
on the substituents. In acetone, macrocycle (1) formed
stable hollow spherical aggregates with multilayer membranes. In contrast,
macrocycle (3) exhibited no production of self-assembled
materials in chloroform. The addition of hexane into the solution
caused the generation of solid spheres and their fused network aggregates,
which were finally transformed into crystals owing to the solvent
effects.