| Popis: |
1,10-dialkylpermethyldecasilanes, R[Si(CH3)2]10R where R = C2H5 1b, C3H7 1c, and C4H9 1d, were prepared from 1,6-dichloropermethylhexasilane in a three-step reaction. Decasilanes 1b-d show the enantiotropic mesophase in the range of 50–105, 22–87, and 23–69 C, respectively. The molecular alignment for the decasilanes in the mesophase were investigated by X-ray diffraction method. These oligosilane molecules are hexagonally ordered to form a multilayer interdigitated structure. The alkyl and silicon chains of these oligosilanes adopt almost all trans conformations and are perpendicular to the layers. These decasilanes show absorption bands with maxima at 293–294 nm in the mesophase. These absorption maxima are red-shifted by 12–14 nm, comparing with those in the liquid state and in solution. |
