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.

Adamantane-based oxacyclophanes containing pyrazines: synthesis, crystal structure, and self-assembly behavior.

Two adamantane-based oxacyclophanes were synthesized by the SNAr reaction of bis-phenol derivatives based on adamantane with 2,6-dichloropyrazine. Their crystal structures had distorted or twisted 1,3-alternate conformations. The oxacyclophanes indicated no formation of spherical aggregates in acetone. However, addition of water into the solution caused the generation of hollow spherical aggregates with a multilayer membrane. Over time, the hollow spheres were induced into fibrous and network assemblies, which were eventually transformed into single crystals.