A novel route for synthesizing silica nanotubes with chiral mesoporous wall structures

Right- and left-handed excess chiral mesoporous silica nanotubes with a helical channel in the wall have been formed by the self-assembly of an achiral surfactant sodium dodecyl sulfate (SDS) in the presence of (R)-(+)- and (S)-(-)- 2-amino-3-phenyl-1-propanol ((R)-(+)- and (S)-(-)-APP) chiral molecules. Transmission electron microscopy combined with computer simulations confirmed the presence of ordered chiral channels winding around the central axis of the tubes of similar to 100 nm inner diameter. Furthermore, it has been found that these have been produced through a specific crystallization route that hollows out the chiral mesoporous silica rod, which is different from the tube synthesis pathways reported previously. The enantiomeric excess ee of chiral mesoporous silica has been increased from 0 to a maximum value of 32% with increasing (R)-(+)-APP/SDS molar ratios from 0 to 0.8.