Structural and spectroscopic study of tripeptide/layered double hydroxide hybrids

A tripeptide (Glutathione, GSH) is chosen as a model drug to intercalate into layered double hydroxides (LDHs) by ion exchange, and a systematic study combining experimental and theoretical investigation is carried on X-ray diffraction (XRD) demonstrates that GSH had been intercalated into LDHs. IR and Raman spectroscopies, and the C-13 NMR chemical shifts, are applied to clarify the characteristic changes in functional groups after intercalation. These results are interpreted with the density functional theory (DFT) calculations in order to verify the experimental data. For the first time, by using XPS for N 1s detecting, the related content of the native guest NO3- and the GSH in the LDHs' interlayer are investigated, and the research results show that the reaction temperature affects the intercalation of GSH based on the XRD patterns. Furthermore, the reaction mechanism of intercalating GSH into LDHs was explained by the intrinsic reaction coordinate (IRC). The present study reveals that GSH as zwitterions (NH3+-COO- formation) in water solvent first suffers hydrogen transfer and proton migration and then could be intercalated into LDH through ion exchange to occupy an interlayer site of NO3-. (C) 2012 Elsevier Inc. All rights reserved.