clathrate: a standalone construct

The term clathrate was coined by H. M. Powell in 1948 (from the Latin clathratus, meaning enclosed by bars or latticed) to name a class of compound in which molecules of one substance, the guest, are physically trapped inside cages formed by the crystal lattice of a second substance, the host, with no ordinary chemical bond joining the two. The guest is held by the geometry of the cage rather than by covalent or ionic attachment, so a clathrate is a type of inclusion compound defined by its structure rather than by a fixed chemical formula. Its best studied family is the clathrate hydrates, also called gas hydrates, in which water molecules build an ice-like framework of cages that enclose small gas molecules such as methane or carbon dioxide, described in E. Dendy Sloan's 2003 review as central to energy, pipeline flow assurance, and climate science. What makes the clathrate a landmark is that it explains how a stable solid can store a guest species at densities far above what the host alone would hold, a mechanism that recurs across crystallography, chemistry, and geoscience wherever the caged storage of small molecules is at issue.[1][2][3]

Unit

A class of inclusion compound: one or more guest species caged within a host crystalline framework

Recovery means

Not applicable

Measured by

Identified by X-ray or neutron crystallography showing guest molecules occupying cages of the host lattice, with spectroscopy confirming host-guest occupancy