Hydrated ions intercalation

The dichalcogenides of group VI do not readily form intercalates with organic molecules. But n-alkylammonium compounds can be prepared by ion-exchange reactions of the hydrated sodium intercalation compounds such as Na j(H20)o g M0S2. Alkylammonium compounds prepared by this route show lattice expansions that depend on the alkyl chain length, very similar to the MX2-n-alkylamine systems described above. This raises the fundamental question whether protonated amines are the actual intercalated species in both the cases, involving reduction of the host. In fact, this constitutes the basis of the new model for the intercalation reaction in MX2 proposed by Schollhorn (1980). 

It is likely that the potassium ions between the kenyaite-type layers cause some structural changes that are difficult to detect in the X-ray powder diagrams but clearly differentiated by the hydration and intercalation behavior. 

Clay materials show a different behavior. They are either cation-poor or cation-rich sheet silicates. They can swell by taking up varying amounts of water between the sheets. If the intercalated cations are hydrated as in montmorillonite, they act as cation exchangers. Montmorillonite, especially when it has intercalated Ca2+ ions, has thixotropic properties and is used to seal up drill holes. The effect is due to the charge distribution on... 

Experiments were performed with various LiAl-X LDHs, with X = Br, NO3 and ISO4. As with the intercalation process, the nature of the anion exerts a powerful influence on the reaction. In the case of sulfate, the deintercalation reaction does not go to completion - only 40% of the available lithium sulfate was released. The deintercalation reaction initially proceeds very quickly, but the process is then halted. The rate of deintercalation is NOs" > Cl > Br . This series does not correspond with data on the anion selectivity for intercalation into Al(OH)3, which is S04 > Cl" > Br" > NO3". Neither is there a correlation of the release data with the heats of hydration of the anions. The series observed arises because the intercalation and deintercalation processes are a balance of a number of factors, including interactions between the guest ions and the host matrix. 

Cai et al.n employed MX-intercalated DNA and ESR to follow the time dependence of individual radical fractions as a function of temperature from 4 K to 195 K in hydrated DNA, and in frozen glassy aqueous solutions containing DNA. By monitoring the ESR signals of MX and of the DNA ion radicals and T(C6)H with time, this work elucidated the ranges of temperatures where... 

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