Synthesis and crystal structure of double-three ring (D3R)-type cage siloxanes modified with dimethylsilanol groups

Naoto Sato, Kazuma Tochigi, Yoshiyuki Kuroda, Hiroaki Wada, Atsushi Shimojima, Kazuyuki Kuroda

    Research output: Contribution to journalArticle

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    Abstract

    The controlled assembly of molecular building blocks enables the rational design of nanomaterials. In this study, two types of cage-type oligosiloxanes with double-three ring (D3R) structures are modified with dimethylsilanol groups to form supramolecular assemblies. One is the siloxane cage derived from Si(OEt) 4 (denoted as the Q 6 cage), and the other is the organosiloxane cage derived from (EtO) 3 Si-CH 2 -Si(OEt) 3 (denoted as the T 6 cage). The syntheses of the silanol-modified cages are performed in two steps: (i) dimethylsilylation of the corner Si-O groups on the Q 6 and T 6 cages to introduce Si-H groups and (ii) subsequent oxidation of the Si-H groups to Si-OH groups. Dimethylsilylation of the cages is conducted at much lower temperatures (−94 and −78 °C for Q 6 and T 6 cages, respectively) than those used for conventional silylation, which is the key to suppressing the deterioration of the unstable D3R structure. The subsequent oxidation of the Si-H groups proceeds successfully, and the crystallization of these molecules is induced by the hydrogen bonds of the silanol groups. The crystal structure of the Q 6 cage modified with dimethylsilanol groups can be regarded as a layered structure with tetrahydrofuran between the layers. In contrast, the T 6 cage modified with dimethylsilanol groups assembled to form a more densely packed structure with no included solvent molecules. The differences between the crystal structures are discussed in terms of the shape of the cages. The insight into the effect of the shape of the cage on its assembly behavior will lead to the designable synthesis of crystalline siloxane-based materials.

    Original languageEnglish
    Pages (from-to)1969-1975
    Number of pages7
    JournalDalton Transactions
    Volume48
    Issue number6
    DOIs
    Publication statusPublished - 2019 Jan 1

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    Siloxanes
    Crystal structure
    Oxidation
    Molecules
    Crystallization
    Nanostructured materials
    Deterioration
    Hydrogen bonds
    Crystalline materials
    Temperature
    silanol

    ASJC Scopus subject areas

    • Inorganic Chemistry

    Cite this

    Synthesis and crystal structure of double-three ring (D3R)-type cage siloxanes modified with dimethylsilanol groups. / Sato, Naoto; Tochigi, Kazuma; Kuroda, Yoshiyuki; Wada, Hiroaki; Shimojima, Atsushi; Kuroda, Kazuyuki.

    In: Dalton Transactions, Vol. 48, No. 6, 01.01.2019, p. 1969-1975.

    Research output: Contribution to journalArticle

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