Layered double hydroxides with a high layer charge (+0.33 per empirical formula unit) intercalate nitrate ions with the molecular plane of the NO3– ion inclined at ca. 70° to the metal hydroxide layer, which results in a basal spacing of 8.8 Å. Three different N–O bond lengths are observed and yield Cs coordination symmetry. At lower charge (0.165 ≤ x ≤ 0.2), a basal spacing of 8.0 Å is observed, which indicates that the nitrate ion is intercalated with its molecular plane parallel to the metal hydroxide layer (coordination symmetry D3h) in a manner isostructural with carbonate‐intercalated layered double hydroxides. Consequently, crystal chemical considerations predict the layer charge corresponding to the idealized composition of the nitrate‐intercalated phase to be +0.165 per empirical formula unit. The [Mg–Al–NO3]0.165 phase is highly ordered with robust crystal growth along [001] and is stable to hydrothermal treatment, in contrast to the carbonate analogue of the same layer charge. Phases obtained with intermediate layer charge (+0.20 to 0.25 per empirical formula unit) exhibit structural disorder arising out of (i) planar faults and (ii) random interstratification of layers comprising nitrate ions in different orientations.

Carbonate-intercalated layered double hydroxides have hitherto been thought to crystallize with rhombohedral symmetry (space group R3̅m). This widely accepted structure model comprises positively charged metal hydroxide layers wherein the cations are disordered. However, spectroscopic studies and simple chemical considerations militate against the possibility of cation disorder. This study shows that the observed powder X-ray diffraction pattern can indeed be fit to a cation-ordered crystal with monoclinic symmetry. With use of the carbonate-intercalated layered double hydroxide of Zn and Al as an illustration, the structure of the layered double hydroxide is refined by the Rietveld method. The resulting structure (space group C2/m, a = √3 × a 0; b = 3 × a 0; c ∼ c 0/3; β ∼ 103°, where a 0 and c 0 are cell parameters of the cation-disordered structure) resolves many of the anomalies of the cation-disordered structure.

Sulfated zirconia (SZ) is an efficient and recyclable catalyst in the selective monoalkylation of resorcinol with MTBE to 4-tertiary butyl resorcinol at low temperature (60 °C).

Layered double hydroxides comprise positively charged metal hydroxide layers and intercalated anions. These materials are obtained from aqueous medium both in nature and in the laboratory. Consequently the layered double hydroxides include a considerable amount of water. The presented study was designed to determine the proportion of water associated with the hydration sphere of the anion as opposed to that of the metal hydroxide slab. Among the two differently bound water species observed in all layered double hydroxides, the weakly bound water is associated with the metal hydroxide