Double-Four-Ring [Si8O12][OH]8 Cyclosilicate and Functionalized Spherosilicate Synthesis from [N(n-C4H9)4]H7[Si8O20]·5.33H2O Cyclosilicate Hydrate Crystals

A new synthesis method for preparing spherosilicates with a double-four-ring (D4R) silicate core (Si8O12) and functional siloxy substituents such as (OSi(CH3)2Cl) on the vertices was discovered. Key to this achievement was the synthesis of [N(n-C4H9)4]H7[Si8O20]·5.33H2O D4R cyclosilicate hydrate precursor crystals having only 5.33 water molecules per D4R unit, which is much smaller than the number in the state-of-the-art tetramethylammonium- and choline-containing cyclosilicate hydrate crystals that have up to 65 water molecules per D4R. The low water content allows the use of bifunctional silylating agents such as dichlorodimethylsilane that lose their chloride functionality upon reaction with water molecules. Dissolution of [N(n-C4H9)4]H7[Si8O20]·5.33H2O crystals in acidified tetrahydrofuran liberates uncharged D4R [Si8O12][OH]8 cyclosilicate molecules, as shown by small angle X-ray scattering and 29Si nuclear magnetic resonance. A concentrated stable solution of [Si8O12][OSi(CH3)2Cl]8 spherosilicate compound was obtained by silylation with Cl2(CH3)2Si. It is a unique way to prepare a stable solution of this attractive spherosilicate with dimethylsilyl chloride chemical functionality suited for derivatization or hybrid material synthesis. With the change in the silylating agent, the new synthesis pathway allows the quantitative synthesis of other spherosilicates such as [Si8O12][OSi(CH3)2H]8 with high yield and purity.

Jaar van publicatie:2017

BOF-keylabel:ja

IOF-keylabel:ja

BOF-publication weight:6

CSS-citation score:1

Authors from:Higher Education

Toegankelijkheid:Closed