Study on the intercalation and interlayer oxidation transformation of L-cysteine in a confined region of layered double hydroxides

Abstract

Two kinds of amino acids (L-cysteine and L-cystine, represented as L-CySH and L-Cys respectively) have been intercalated into MgAl layered double hydroxides by coprecipitation. The structure and composition of the intercalated materials have been characterized by X-ray diffraction (XRD) and elemental analysis. Furthermore, the oxidation of L-CySH intercalated LDHs by, respectively, hydrogen peroxide and bromine has been studied. Based on the FT-Raman, FT-IR, and ¹³C MAS NMR spectra data, it has been found that H₂O₂ oxidized the interlayer L-CySH to cystine, while the oxidation product of intercalated L-CySH by Br₂ was cysteic acid regardless of the bromine/cysteine ratio, which is different from the bulk reaction. Therefore, this layered material may have prospective application as the basis of a novel “molecular reactor” for confined chemical reactions.