Imprinting Chirality in Silica Nanotubes by N-Stearoyl-serine Template

In this article, we describe the synthesis of imprinted chiral silica nanotubes based on the use of a chiral N-stearoyl L-serine (C(18)Ser) anionic surfactant as the chiral template. The resulting chiral silica nanotube structures were characterized by electronic microscopy (transmission electron microscopy (TEM) and scanning electron microscopy (SEM)) and nitrogen isotherms that proved the formation of well-ordered silica nanotubes. A C18Ser surfactant template was used for the preparation of the silica nanotubes, due to its effective molecular organization within the silica network. After chemical extraction of the chiral template, the enantioselectivity feature of the silica nanotubes was confirmed by selective adsorption of the enantiomers using circular dichroism (CD) and isothermal titration calorimetry (ITC) measurements. Although these measurements show a relatively low chiral selectivity of the silica nanotubes (ca. 6% enantiomeric excess), the system described here offers new approaches for the application of chiral porous materials in chirality.