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’...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 SiO_(4)F 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(^(1)H,^(13)C{1H},^(19)F,and^(29)Si{1H}).Carbonization of the as-obtained hybrid materials and subsequent treatment with hydrofluoric acid resulted in microporous carbon with surface areas up to 1060 m^(2)g^(-1).Calcination of the hybrid materials produced fluorine-doped silica with BET surface areas up to 239 m^(2)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 m^(2)g^(-1))or mesoporous silica(687 m^(2)g^(-1)).展开更多
基金support from the DFG research group 1497“Organic-Inorganic Nanocomposites through twin polymerization”.
文摘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 SiO_(4)F 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(^(1)H,^(13)C{1H},^(19)F,and^(29)Si{1H}).Carbonization of the as-obtained hybrid materials and subsequent treatment with hydrofluoric acid resulted in microporous carbon with surface areas up to 1060 m^(2)g^(-1).Calcination of the hybrid materials produced fluorine-doped silica with BET surface areas up to 239 m^(2)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 m^(2)g^(-1))or mesoporous silica(687 m^(2)g^(-1)).
