Microporous layered silicates: old but new microporous materials
Microporous materials are, nowadays, majorly known as zeolites and metal–organic frameworks. Although layered inorganic solids like swelling-type clay minerals are also considered microporous materials because of the expandable and modifiable interlayer nanospace, well-defined open micropores still remain difficult to form there, which can cause disadvantages (e.g., slow diffusion and poor shape-selective adsorption). Layered silicates with microporous layers, so called microporous layered silicates, are a unique class of microporous materials having both zeolite-like micropores within the layers or cup-like cages as part of the layers and expandable interlayer spaces like layered clay minerals. Here, we review recently reported microporous layered silicates, AMH-3, CIT-10, ITQ-8, magadiite, HUS-1 and HUS-5. We highlight how the structures of these microporous layered silicates affect their properties and applications. Some of them exhibit applications, including molecular recognition, that are not delivered by usual layered silicates and zeolites.