Cationic intercalation chemistry

Cationic intercalation chemistry is based on coupled ion-electron transfer reactions. 

Three areas of the intercalation chemistry of clays have received very detailed study and will be described further (a) intercalation of organic cations and neutral organic molecules (b) pillaring reactions and (c) clay polymer nanocomposites. 

Compounds Containing Perovsldte Layers. A second class of layered oxides have structures related to the three-dimensional perovsldte lattice and include the Auriv-iUius phases, the Ruddlesden Popper phases and the Dion-Jacobson phases. The general composition can be written M [A iB 03 +i] where A is an alkaline or rare earth metal, and B is niobium or titanium. In the AurivUhus phases M = Bi202 +, whereas M is an aUcah metal cation in the ion-exchangeable Ruddlesden Popper a = 2) and Dion-Jacobson a = 1) phases. The relationships between the three structure types is shown in Figure 14. The intercalation chemistry of the Dion Jacobson phases was the first to be studied. 

The field of intercalation chemistry in layered silicates is huge. It includes many types of intercalates, and a large variety of host structures that can be modified before intercalation by various exchange reactions. Organoclays, for example, represent a family of compounds resulting from the introduction of organic cations by ion exchange and which also allow intercalation. 

The second situation is well illustrated by phases that are built up from clusters of Mog octahedra enclosed in pseudo-cubes of eight chalcogen atoms. For small ions the structure formally provides at least 6, or even 12, possible lattice sites, but the molecular levels of the clusters have 20 electrons within a possible maximum population of 24 electrons. This leads to an electronic limit with a maximum of four intercalated monovalent cations". Changing the chemistry of the cluster by substituting, e.g., Ru for Mo changes the intercalation chemistry according to the new electronic population of the cluster. 

Hibma TJ (1982) Stmctural aspects of monovalent cation intercalates of layered dichacogenides. In Whittingham MS, Jacobson AJ (eds) Intercalation chemistry. Academic, New York, pp 285-313... 

Clay minerals or phyllosilicates are lamellar natural and synthetic materials with high surface area, cation exchange and swelling properties, exfoliation ability, variable surface charge density and hydrophobic/hydrophilic character [85], They are good host structures for intercalation or adsorption of organic molecules and macromolecules, particularly proteins. On the basis of the natural adsorption of proteins by clay minerals and various clay complexes that occurs in soils, many authors have investigated the use of clay and clay-derived materials as matrices for the immobilization of enzymes, either for environmental chemistry purpose or in the chemical and material industries. 

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