In-depth study on intercalating threonine into layered double hydroxides

The precursors of Mg–Al layered double hydroxides (LDHs) were synthesized and threonine (Thr) was incorporated into LDHs via ion exchange procedure. XRD and low-angle XRD demonstrate that Thr anions have been inserted into the layers. Molecular model is built up to present the possible arrangement and orientation of the intercalated substances based on XRD patterns. IR and Raman spectroscopy are applied to illustrate the characteristic changes in functional groups. After intercalation, with full elemental analysis and X-ray Photoelectron Spectroscopy (XPS) for N 1s detecting, the nitrate/Thr molar ratio is 1:5, and the empirical formula is [Mg0.758Al0.242(OH)2](C4H9NO3)0.202(NO3)0.0403 · 1.24H2O. Measurement of TGA–DTA pictures the weight loss regions to exhibit the composition structure of LDHs. Detected by 13C MAS NMR spectra, it is supposedly verified that Thr anions are linked to the layers with its axis due to the ionic interaction between –COO− and cationic layers.

Threonine intercalating into layered double hydroxides (Mg:Al = 3:1) with possible arrangement and orientation in the interlayer.Figure optionsDownload as PowerPoint slideResearch Highlights
► Reaction intensity and temperature were the major factors affecting the experimental result.
► Two modes of ion exchange and self-assembly were binding together.
► XPS for N 1s detecting shows that the native guests NO3− were not totally supplanted.
► 13C NMR spectra verify that Thr in the interlayer would be rearranged regularly.