Efficient synthesis of ordered organo-layered double hydroxides

Abstract

Layered double hydroxides (LDHs) intercalated with terephthalate anions represent one of the most studied organo-LDH systems. We have prepared MgAl terephthalate-LDHs using an efficient hydrothermal approach from the respective metal hydroxide precursors. In contrast to terephthalate LDHs prepared by other methods, and as a result of the absence of competing anions, a large excess of terephthalate acid was not required, thereby allowing for an environmentally attractive synthetic route. The LDHs were prepared from starting reactant Mg/Al ratios of 2, 3, 4 and 5 and were found to exhibit unusually high degrees of order as evidenced from X-ray diffraction studies, especially at the Mg/Al ratio of 2. Further analysis of the X-ray diffraction data showed that, as in previous studies, three distinct interlayer arrangements could be identified. Scanning electron microscopy was used to compare and contrast the morphology of crystals formed with those prepared by other methods of LDH synthesis and confirms the high degree of structural integrity achieved by the synthetic method.