Preparation of Mesoporous 1,4-Phenylene-silica Nanorings through a Dual-templating Approach

Mesoporous 1,4-phenylene-silica nanorings were prepared using cetyltrimethylammonium bromide （CTAB） and （S）-2-methyl-l-butanol as a chiral dopant in concentrated aqueous NH3 solutions. Transmission electron mi- croscopy images of the samples indicated that the nanorings were formed by bending nanorods 360°. With increasing the stirring speed or the （S）-2-methyl-l-butanol/CTAB molar ratio, the morphologies of mesoporous 1,4-phenylene-silicas changed from helical nanofibers to nanorings, and then to nano-saddles. Circular dichroism spectra of these hybrid silicas indicated that they were chiral.