Insertion of chromium(III) ascorbate complex into layered double hydroxide through reduction of intercalated chromate by ascorbic acid

The reaction of ascorbic acid with intercalated chromate of MgAl layered double hydroxides (LDH) at neutral pH leads to in-situ formation of the chromium(III) ascorbate complex, [Cr(Hasc)2(OH)2]−(Hasc = ascorbate dianion), in the interlayer space. The isolated solid was characterised by elemental analyses, powder X-ray diffraction (PXRD), thermal studies, FT-IR and UV–Visible diffuse reflectance spectroscopy (UV–Vis/DR). PXRD showed an increase of the basal spacing to 10.5 Å indicating the intercalation of the Cr(III) complexes. FT-IR and UV–Vis/DR spectra also confirmed the in-situ formation of the ascorbate complex in the interlayer space. The interlayer complex was stable up to ~ 200 °C and was decomposed above 400 °C with the formation of small amounts of Cr6+ as indicated by the UV–Vis/DR spectra. This described method may be useful for intercalation of other biologically important anionic metal complexes in LDHs.