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Issue 10, 2018
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Chiral molecular fluoridosilicates and their twin polymerization for the preparation of fluorine-doped mesoporous silica and microporous carbon

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Abstract

The syntheses of chiral pentacoordinated fluoridosilicates and their conversion into fluorine-doped silica and mesoporous carbon are reported. Starting from 4H,4′H-2,2′-spirobi[benzo[d][1,3,2]dioxasiline] (1) and 8,8′-di-tert-butyl-4H,4′H-2,2′-spirobi[benzo[d][1,3,2]dioxasiline] (2), the corresponding fluorido complexes 3 and 4 were obtained by the addition of potassium fluoride to the spirocyclic silicon salicylic alcoholates 1 and 2 in the presence of 18-crown-6. The pentacoordinated geometry around the silicon atom of the SiO4F type in 3 and 4 was proved using single-crystal X-ray diffraction analysis. DSC measurements were used to study the thermal behavior of the compounds with regard to their usability in the twin polymerization process. Hence, polymerization of 3 and 4 and the simultaneous twin polymerization of the fluoridosilicate 3 with spirocyclic 1 gave fluorine-doped phenolic resin/silica composites as confirmed by solid state NMR spectroscopic studies (1H, 13C{1H}, 19F, and 29Si{1H}). Carbonization of the as-obtained hybrid materials and subsequent treatment with hydrofluoric acid resulted in microporous carbon with surface areas up to 1060 m2 g−1. Calcination of the hybrid materials produced fluorine-doped silica with BET surface areas up to 239 m2 g−1. Additionally, the synthesis of hybrid materials using the additive assisted twin polymerization of 1 with either tetra-n-butylammonium fluoride or KF gave either microporous carbon (1219 m2 g−1) or mesoporous silica (687 m2 g−1).

Graphical abstract: Chiral molecular fluoridosilicates and their twin polymerization for the preparation of fluorine-doped mesoporous silica and microporous carbon

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Publication details

The article was received on 06 Jun 2018, accepted on 10 Sep 2018 and first published on 10 Sep 2018


Article type: Research Article
DOI: 10.1039/C8QI00533H
Citation: Inorg. Chem. Front., 2018,5, 2648-2656
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    Chiral molecular fluoridosilicates and their twin polymerization for the preparation of fluorine-doped mesoporous silica and microporous carbon

    F. Roschke, T. Rüffer, A. Seifert, K. Nagel, S. Spange, H. Lang and M. Mehring, Inorg. Chem. Front., 2018, 5, 2648
    DOI: 10.1039/C8QI00533H

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