Intercalation (chemistry)

Under intercalation (from the Latin intercalare = insert ) in the chemical sense refers to the incorporation of molecules, ions ( rarely atoms) into chemical compounds, which do not significantly change their structure during the deposition process.

Inorganic Chemistry

In inorganic chemistry, intercalation refers to the incorporation of atoms, ions or small molecules between the crystal lattice planes of layered crystals, for example, the intercalation of alkali metals in graphite ( see figure). The resulting compounds are referred to as intercalation.

Thus, a crystal structure can form intercalation compounds, the interaction forces within the layers of large, between adjacent layers must be small. Between the host lattice and the guest components strong interactions must be possible. To induce the intercalation, the interlayer cations of solvation is particularly suitable. It depends on both the chemical properties of einzulagernden component, but also on the chemical nature of the host lattice, such as the storage takes place. Often, in addition to pure van der Waals interactions and Lewis acid - base interactions play a role.

The host lattice can be varied greatly in their chemical nature; of the quasi- metallic layers in graphite or in the transition metal sulfides NbS2 or TaS2 to the semiconducting systems such as TiS2 and SnS2 and non-conductive compounds such as clay minerals (eg kaolinite ).

Many layers of mesh carry inherently negative layer charges, such as micaceous phyllosilicates. Electrically neutral host lattice are rather rare; For example, the above-mentioned kaolinite. Some "neutral" host lattice to be formed only by applying a strong reducing agent capable of intercalation complexes. In some cases, allow the incorporation to the use of non-stoichiometric compounds. The stoichiometry is achieved by reducing agents or electrochemical reduction. Methods for this are the cyclic voltammetry, the Electrogravimetry and Galvanostatik.

Practical and technical application find these types of reactions, inter alia,

• Accumulators and batteries
• Soil, Environmental and Geochemistry ( absorption and storage behavior of soils )
• Industrial production and packaging of medicines, fertilizers, plant protection

Biochemistry

From intercalation into the deoxyribonucleic acid ( DNA) is when certain molecules that are completely or partially planar insert in the double helix of DNA between adjacent base pairs. This stored the replication and transcription of DNA is disrupted. During the replication process, there is a grid mutation. The intercalation is therefore held responsible for the mutagenic action of many members of this class, and also the chemotherapeutic effect of antibiotics or cytostatics such as actinomycin or anthracyclines such as daunorubicin, is attributed, among other things, the intercalation. Compounds with intercalative properties in addition to the mentioned cytostatics for example include polyaromatic hydrocarbons and dyes of phenanthridine type, such as ethidium bromide, or proflavine - type ( Falbe and Regitz, 1992; Mutschler 1996). And indirubin derivatives intercalate in the DNA.