Twin-bowl-shaped tris-(spiroborate) cyclophanes bearing pyridyl groups have been prepared for the construction of proton-responsive supramolecular polymers. Preparation of the pyridyl twin bowls was carried out by the reaction of 6,6′-(3-pyridyl)-2,2′,3,3′-tetrahydroxy-1,1′-binaphthyls and an equimolar amount of boric acid in N,N-dimethylformamide in self-organization manner, as previously reported. The reversible acid/base response of the pyridyl twin bowls was evaluated by the addition of hydrochloric acid and aqueous sodium hydroxide. The assembly disassembly modulation of the supramolecular polymers composed of pyridyl twin bowls and the tricationic iridium-(III) complex was also examined. Dissociation of the supramolecular polymers occurred by the addition of hydrochloric acid, and its reconstruction was realized by the addition of aqueous sodium hydroxide. The opposite behavior was observed when the dianionic palladium-(II) complex was employed as a guest. The addition of acid led to the formation of the aggregate that was dissociated by the addition of base.

Successive guest-containing tubular polymer was prepared by the olefin metathesis polymerization of tris(spiroborate) twin bowl after the formation of supramolecular polymer. The cationic iridium(III) complexes were topologically fixed inside the polymer to form a peapod-like structure. The polymer was evaluated by SEC, ICP-AES, and DLS analyses, and string-like structures were found in the AFM observation of the peapod polymer.

Multicomponent construction of the tetrakis(spiroborate) anionic nanocycles was achieved by reacting bis(dihydroxynaphthalene)s with tetrahydroxyanthraquinone in the presence of boric acid in a self-organized manner. These nanocycles exhibited selective molecular recognition behavior toward cationic guests such as methyl viologen derivatives. Formation of a supramolecular ring@ring and a guest@ring@ring structure was observed by combining the anionic nanocycle and the vinylogous analog of cyclobis(paraquat-p-phenylene).

Multilayered spiroborate nanocycles were prepared from tris- or tetrakis(dihydroxynaphthalene) and tetrahydroxyanthraquinone as pillar and crossbar units via the reversible formation of a spiroborate linkage. The four-layered spiroborate nanocycle recognized two cationic aromatic guests simultaneously and exhibited the ability to form a supramolecular one-dimensional array by combining with methyl viologen dimer as the ditopic guest.

Lanthanide(III)-containing metallosupramolecular arrays were prepared in the crystalline state simply by mixing trifluoromethanesulfonate salts of yttrium(III), lanthanum(III), europium(III), terbium(III), erbium(III), and ytterbium(III) with a rac-tris(spiroborate) twin bowl in N,N-dimethylformamide (DMF). In the crystal, the lanthanide(III) ion coordinated to eight or nine DMF molecules to form spherical tricationic complexes, and the spiroborate twin bowl iteratively glued the complexes to each other to form one-dimensional arrays that were unidirectionally packed in the crystal. In each case, the array structure was stabilized by many aromatic C–H···π interactions and C–H···O hydrogen bonds between the twin bowls and the lanthanide(III) complexes. Among the lanthanide(III) ions, yttrium(III), terbium(III), erbium(III), and ytterbium(III) gave almost the same crystal lattice and packing, whereas a different array structure and crystal packing was observed when lanthanum(III) and europium(III) were used, probably due to the difference of the ionic radii of the lanthanide(III) ions.

Twin-bowl-shaped tris(spiroorthocarbonate) cyclophanes were designed and prepared as ditopic hosts for electrically neutral or electron-rich guests. Preparation of the desired cyclophanes was achieved by cyclotrimerization of 2,2′,3,3′-tetrahydroxy-1,1′-binaphthyl (THB) via the transesterification of tetraphenyl orthocarbonate or dichlorodiphenoxymethane. In those reactions, bis(spiroorthocarbonate) cyclophane containing two THB units was also formed as the kinetically favored product. The spiroorthocarbonate twin bowl exhibited ditopic molecular recognition toward fullerene C60 in the crystalline state.

Heterobimetallic supramolecular polymers were prepared by treatment of the supramolecular polymers composed of tris(spiroborate) type molecular connecting modules with a potassium cation. On the other hand, the addition of a barium cation led to dissociation of the supramolecular polymer chain. Modulation of polymer formation was realized by the use of small metal cations as a control factor.