Everything about Clathrates totally explained
A
clathrate or
clathrate compound or
cage compound is a
chemical substance consisting of a
lattice of one type of molecule trapping and containing a second type of molecule. The word
clathrate is derived from the
Latin clatratus meaning
with bars or a lattice. An example of a clathrate is
clathrate hydrate, a special type of gas
hydrate in which a lattice of
water molecules encloses molecules of a trapped
gas. Scientists believe that compounds on the sea bed have trapped large amounts of
methane in similar configurations. Researchers have begun to investigate
silicon and
germanium clathrates for possible
semiconducting and
superconducting properties.
A clathrate therefore is a material which is a weak composite, with molecules of suitable size captured in spaces which are left by the other compounds. They are also called
host-guest complexes,
inclusion compounds, and
adducts (chiefly in the case of
urea and
thiourea). They used to be called "molecular compounds".
In 1945, H. M. Powell named these compounds
clathrate.
Clathrate complex used to refer only to the inclusion complex of
hydroquinone, but recently it has been adopted for many complexes which consist of a host molecule (forming the basic frame) and a guest molecule (set in the host molecule by interaction). The clathrate complexes are various and include, for example, strong interaction
via chemical bonds between host molecules and guest molecules, or guest molecules set in the geometrical space of host molecules by weak
intermolecular force. Typical examples of host-guest complexes are
inclusion compounds and
intercalation compound.
The history of clathrate compounds is relatively new.
Clathrate hydrates were discovered in 1810 by
Sir Humphrey Davy. Clathrates were studied by P. Pfeiffer in 1927 and in 1930, E. Hertel defined molecular compounds as substances decomposed into individual components following the
mass action law in solution or gas state. Therefore, basic information about clathrate compounds (then called molecular compounds) was known in those days. The development of clathrate compounds was attained by analyzing crystal structure by Powell (mentioned above), and they were applied to the separation of
paraffin using a urea or thiourea host. Thereafter,
cyclodextrin,
crown ether, and
cryptand were found as host molecules (see figure). A much studied host molecule is
Dianin's compound.
In analyzing and separating techniques, the concept of inclusion compounds has taken root and many applications of them are known. It is possible to isolate not only chemically different species but also structural isomers, positional isomers (enantiomers and diastereomers), and radioactive isomers using clathrate compounds.
The structure of Clathrates is also related to the structure of foams (see
Weaire-Phelan structure).
For a theory regarding the sudden release of
methane clathrate from ocean sediments see
clathrate gun hypothesis.
Further Information
Get more info on 'Clathrates'.
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