Controllable shape selectivity based on highly ordered carbonyl and methyl groups in simple β-structural polypeptide on silica

Poly(l-alanine)-grafted porous silica (Sil-Ala22) was prepared by polymerization of N-carboxyanhydride of l-alanine initiated by 3-aminopropylated silica. The retention behaviors of the column packed with Sil-Ala22 were investigated by using alkylbenzenes and polycyclic aromatic hydrocarbons as injection samples in liquid chromatography. The Ala22 phase was in a rigid β-form structure and thus provided specific interaction sites, which were derived from the highly ordered carbonyl and methyl groups. These interaction sites bring unique molecular-shape discriminations: molecular-length and non-planarity selectivity, which are controllable by altering organic solvent used as a part of mobile phase.