Hybrid inorganic/organic composites of Mg-Al layered double hydroxides intercalated with citrate, malate, and tartrate prepared by co-precipitation

Inorganic/organic composite materials composed of Mg-Al layered double hydroxides (Mg-Al LDHs) intercalated with citrate (C6H5O73-), malate (C4H4O52-), or tartrate (C4H4O62-) anions were prepared by a co-precipitation technique and characterized by X-ray diffraction and compositional analyses. The molecular orientation of the organic component in the interlayer space was determined. At low intercalation levels, citrate ion was inclined at an angle of 26 degrees relative to the brucite-like layers of Mg-Al LDH. At higher solution concentrations, both the Mg(C6H5O7)(-) complex and free C6H5O73- were isotropically oriented in the interlayer space. For both malate-Mg-Al LDH and tartrate-Mg-Al LDH, the organic anions were inclined at 26 degrees relative to the Mg-Al LDH layers regardless of anion concentration. (C) 2008 Elsevier Ltd. All rights reserved.