materials Inclusion compounds are often molecules, whereas . Intercalation compounds are not 3-dimensional, unlike clathrate compounds. Photolytically-sensitive caged compounds have been examined as containers for releasing a drug or reagent. Zeolites are another type of crystalline structures that form a framework with cavities in which guest species can reside. Unlike clathrates, zeolites are defined by the tetrahedra linking of four oxygen atoms surrounding a cation. The guests are also not required to fill the open cavities. Zeolite structures are defined by the diverse building units of the framework, as opposed to cavity structures in clathrates. Similar applications have been explored. Silica clathrasil are compounds structurally similar to clathrate hydrates with a SiO2 framework and can be found in a range of marine sediment. See also Molecular tweezers Clathrate hydrate References