Dimerization Control in the Self-Assembly Behavior of Copillar[5]arenes Bearing ω‑Hydroxyalkoxy Groups

Two novel copillar[5]­arenes bearing ω-hydroxyalkoxy groups are synthesized and their self-assembly properties are studied by 1H NMR spectroscopy, specific viscosity, and X-ray measurements. The copillar[5]­arene 2b bearing a 6-hydroxyhexyloxy group exhibits a reversible self-assembly behavior, leading to the formation of the self-inclusion monomer and hugging dimers. The reversible self-assembly behavior can be controlled by tuning solvent, temperature, guest, and H-bond interaction. However, the copillar[5]­arene 2a bearing a short 4-hydroxybutyloxy group does not show such a self-assembly behavior to the formation of the self-inclusion monomer and hugging dimers.