Molecular-length and chiral discriminations by β-structural poly(L-alanine) on silica

Poly((L)- alanine)-grafted porous silica (Sil-Ala(22)) was prepared by polymerization of N-carboxyanhydride of (L)-alanine initiated by 3-ammopropylated silica. Its selective interaction with aromatic guest molecules was evaluated by the retention time in liquid chromatography using the column packed with Sil-Ala(22). Sil-Ala(22) showed a specific selective retention with discriminating molecular shapes, such as molecular length, linearity and planarity. This selectivity can be explained by a multiple pi-pi interaction with the carbonyl groups one dimensionallyaligned on the rigid beta-form structure in the peptide main chain. Chiral separation with Sil-Ala(22) was also described. (c) 2004 Elsevier B.V. All rights reserved.