A perfect “Janus-cube” octasilsesquioxane, a nanometer-scale Janus particle with two different types of substituents, was synthesized through the cross-coupling of a “half-cube” cyclic sodium siloxanolate with another half-cube cyclic fluorosiloxane. The structure was confirmed by X-ray crystallography to be a Janus cube. The overall synthesis is simple and does not require drastic separation methods compared with previous methods. The synthesis of the Janus cube demonstrates a novel siloxane bond-forming reaction involving the coupling a silanol salt and fluorosilane. The reaction is mild, does not result in acid generation, and could be applied to the construction of other novel siloxane compounds.

A perfect “Janus-cube” octasilsesquioxane, a nanometer-scale Janus particle with two different types of substituents, was synthesized through the cross-coupling of a “half-cube” cyclic sodium siloxanolate with another half-cube cyclic fluorosiloxane. The structure was confirmed by X-ray crystallography to be a Janus cube. The overall synthesis is simple and does not require drastic separation methods compared with previous methods. The synthesis of the Janus cube demonstrates a novel siloxane bond-forming reaction involving the coupling a silanol salt and fluorosilane. The reaction is mild, does not result in acid generation, and could be applied to the construction of other novel siloxane compounds.

The facile synthesis of all-cis-tetrasiloxycyclotetrasiloxanes (extended cyclic siloxanes) [i-BuSi(OSiHMe₂)O]₄ 1, [PhSi(OSiHMe₂)O]₄ 2, and [CH₂ = CHSi(OSiHMe₂)O]₄ 3 was accomplished via sodium or potassium silanolates from respective trialkoxysilanes. The treatment of 1 or 2 with m-chloroperoxybenzoic acid afforded respective extended cyclic silanols [i-BuSi(OSiMe₂OH)O]₄ 4 and [PhSi(OSiMe₂OH)O]₄ 5. The structures of 4 and 5 were unequivocally established by X-ray crystallography. Among these new compounds, compound 3 possesses both vinyl and hydrosilyl groups in the molecule, thus this could serve as a potential monomer of well-defined cage silsesquioxanes. Extended cyclic silanols 4 and 5 contain four silanol moieties in the same direction, and application of host molecules or building units of cage silsesquioxanes is expected.

Azobenzene-containing silanol dyes were synthesized, and their applicability to dye-sensitized solar cells was investigated. Silanol dyes showed better effectiveness when compared with conventional carboxy-substituted azobenzene dyes. Moreover, silanol dyes showed better durability than carboxyl dyes; ∼90% of silanol dyes remained intact on the TiO₂ electrode of the solar cell after being immersed in water for 96 h, whereas in the case of carboxy dyes this figure was less than 20%. Copyright © 2010 John Wiley & Sons, Ltd.

As a continuation of our previous studies on thermostable materials, heptacyclic laddersiloxanes and ladder polysilsesquioxane were synthesized. The first heptacyclic laddersiloxanes were obtained by chlorination of pentacyclic laddersiloxanes prepared using our stereocontrolled synthesis procedure; thereafter, the heptacyclic laddersiloxanes were made to react with disiloxanediol. Ladder polysilsesquioxane was obtained from cis–trans–cis-tetrabromotetramethylcyclotetrasiloxane by spontaneous hydrolysis and dehydration. The spectral and thermal properties of these new compounds were investigated. It was observed that the thermal stability of these compounds increases with the ring number. Copyright © 2010 John Wiley & Sons, Ltd.