Caged Compounds small molecule

A claihrate compound means, literally, an enclosed compound, a term applied to a solid molecular compound in which a molecule of one component is physically enclosed in the crystal structure of a second compound, so that the properties of the aggregate arc essentially those of the enclosing compound. Examples of such cage compounds" are those of the small molecules of SO . CO.. CO and the noble gases with ice and hydroquinone. which have very open crystal structures. Another example is the claihrate of benzene with nickel cyanide. 

The hollow interior of dodecahedrane and other organic cage compounds described in section 4.9 is much too small to envelop atoms, ions, or molecules. Tight closed-shell macromolecules have been obtained from vesicles by several research groups, by polymerization of amphiphiles possessing double or triple bonds within the membrane or at the head groups. Smaller, but well-defined, closed-shell containers have been obtained by two other methods described below, namely by directed synthesis and by formation of closed-shell all-carbon molecules in graphite vapor. 

Another arena in which topologically restrained molecules are of importance involves endothelial compounds for example, a small molecule or ion inside a fisular cage, such as a fullerene. The first of these to be discovered occurred when Diedrich et al. [5] doped C60 with potassium to encapsulate 3 potassium atoms inside the cage. The systemic name for this compound would now be formed by augmenting the name for fullerene that had been developed earlier in Formulas (42) or (43) of Chapter 3 with a semicolon, followed by a zero numbered locant branch e.g., °(K,K,K) — assuming that the three potassium atoms are independent of one another i.e.,... 

Clathrate hydrates (known also as gas hydrates) belong to a large class of crystalline, non-stoichiometric, inclusion-compound materials that are stable within a certain range of pressure and temperature. The host solid framework structure is made up of water molecules, connected through hydrogen bonds that form cavities (cages) . The cavities can be stabilized by the inclusion of small molecules such as CH4, CaHg, CO2, N2, Ar, etc. Over 100 different molecules are known to form hydrates. 

In certain compounds, the so-caUed endohedral fuUerenes, atoms or small molecules are incorporated into the cage without forming a covalent bond to the fullerene scaffold. The notation M C (pronounced M at C ) is used to indicate the position within the fuUerene, with M representing the atom or molecule inside the cage. In this way, hetero- and endofuUerenes can clearly be distinguished, for... 

For hollow objects like the fullerenes, a general distinction has to be made between outside and inside reactivity. Modifications to the outside are termed exohedral functionalization, and those to the inside are endohedral. Both variants are observed for the fullerenes. Classical fullerene chemistry deals with exohedral functionalization by one or more groups attached to the carbon atoms. Endohedral chemistry, on the other hand, studies compounds consisting of atoms or small molecules included in the cavity within the fullerene cage. The exohedral processes may further be divided into covalent and noncovalent interactions with the reaction partner. 

Some aluminosilicates are known as zeolites. Zeolites are part of a class of compounds known as molecular sieves and consist of an aluminosilicate frame with group 1 or 2 cations trapped inside tunnels or cages. In addition to their ability to act as ion exchangers, they can selectively remove small molecules, such as water, from mixtures - hence the term molecular sieves (Fig. 19.14). 

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