Preparation of Chiral 1,4-Phenylene-silicas via Chiral Low-molecular-weight Amphiphiles

Chiral organic-inorganic hybrid silicas can be prepared via the self-assemblies of chiral surfactants and gelators as templates. However, the relationship between the chirality of the hybrid silica and the structure of the surfactant/gelator has not been systemically studied. Herein, a series of chiral low-molecular-weight amphiphiles(LMWAs) derived from L-valine was synthesized. Their alkyl chains were n-butadecyl, n-hexadecyl and n-octadecyl, respectively. They can form viscous liquids in pure water, and physical gels in tetrahydrofuran, cyclohexanone, acetonitrile, acetone, chlorobenzene and nitrobenzene. Chiral 1,4-phenylene-silicas were prepared via the self-assemblies of these LMWAs as templates. With increasing the alkyl chain length, the 1,4-phenylene-silicas changed from short mesoporous nanorods to long nanotubes. The circular dichroism spectra of the 1,4-phenylene-silicas indicated that the long nanotubes exhibit the strongest chirality.