Intercalation chemistry of the novel layered double hydroxides [MAl4(OH)12](NO3)2·yH2O (M = Zn, Cu, Ni and Co). 1: New organic intercalates and reaction mechanisms

Abstract

The intercalation chemistry of a recently synthesized family of layered double hydroxides, [MAl 4 (OH) 12 ](NO 3 ) 2 ?yH 2 O (M = Zn, Cu, Ni, Co), has been explored. A range of dicarboxylates, mono-and disulfonates have been intercalated successfully, and the resulting materials fully characterised. The interlayer spacing of the dicarboxylates is found not to vary linearly with the length of the carboxylate chain, but instead the acid species are arranged so that the ends of the dicarboxylate chains point directly at the localized metal atoms in the layers. In situ diffraction experiments have been performed to investigate the kinetics and mechanisms of the intercalation processes. The dicarboxylates are found to intercalate very quickly, with the reactions being complete within a few minutes at room temperature. In contrast, the sulfonates intercalate more slowly, and quantitative kinetic parameters may be measured for these reactions. All the reactions were found to be direct one-step transformations. The sulfonate intercalation processes are proposed to be nucleation controlled in the vast majority of cases for the M = Zn, Cu and Co materials, with the rate limiting step being the expansion of the interlayer space to accommodate the relatively large organic guest anions. In contrast, the reactions of the M = Ni LDH are found to be purely diffusion controlled: as soon as the guest reaches the host particles, it intercalates.

Removal of Nitrophenol from Water by Dodecyl Sulfate Modified Layered Double Hydroxides

“…Layered double hydroxides, therefore serve as a good template for the formation of functional composite materials by host-guest structural design and assembly. The species, composition and ordering of the metallic cations, stacking sequence of layers, size and orientation of the guest, as well as the interactions between the negatively charged guest and the positively charged LDH layers are all critical factors influencing the structure of LDHs and thus determining the specific applications of these materials [12][13][14][15] .…”

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

“…The data are given in Table 2. Dicarboxylic acids in Li/Al LDHs are aligned perpendicular to the hydroxide layer [4] but LDH systems with Zn, Cu, Ni and Co showed significant departures from linear dependence [3] although succinate intercalates seemed to be consistently tilted at about 55 • . Malonate and glutarate lack the symmetry of the other diacids and can be twisted, depending on the cation and crystal structure, particularly the glutarate.…”

The selective intercalation of organic carboxylates and sulfonates into hydroxy double salts

“…This energy is comparable to that obtained for other anion exchange intercalation processes. 39 As for intercalation into Zn 5 -NO 3 , 1,2-BDC is observed to intercalate much more rapidly than 1,4-BDC (see Table 2). For 1,2-BDC intercalation, the value of n is around 1.5, suggesting that the mechanism may involve deceleratory nucleation followed by 2D diffusion control.…”