High-pressure Raman spectroscopic and other structural studies of hydrotalcites containing intercalated dicarboxylic acid anions

The results of pressure-tuning Raman spectroscopic, X-ray powder diffraction and solid-state C-13-NMR studies of selected dicarboxylate anions intercalated in a Mg-Al layered double hydroxide lattice are reported. The pressure dependences of the vibrational modes are linear for pressures up to 4.6 GPa, indicating that no phase transitions occur. The interlayer spacings show that the oxalate, malonate and succinate dianions are oriented perpendicular to the layers, but the glutarate and adipate are tilted. The solid-state C-13-NMR spectra of these materials show full chemical shift anisotropy and, therefore, the anions are not mobile at room temperature. Copyright (c) 2011 John Wiley & Sons, Ltd.