pyramonal

Pyramonal is a term used in materials science to describe a class of crystalline frameworks that feature pyramid-like motifs built from metal centers and bridging ligands. The name combines "pyramid" and the suffix "-al." Pyramonal structures are characterized by nodes with pyramidal coordination, often forming cavities or channels that resemble polyhedral pores. They can be based on metal-oxide nodes or on metal-organic clusters connected by organic linkers.

Synthesis and occurrence: Pyramonal frameworks have been reported in both inorganic and metal-organic systems. They can be produced via solvothermal, hydrothermal, or high-temperature solid-state methods, frequently with structure-directing agents to promote pyramidal connectivity. The resulting materials typically exhibit porosity and varying chemical stability depending on composition.

Properties and applications: The porous nature yields high surface areas and selective adsorption properties, making pyramonal materials candidates for gas storage, separations, and catalysis. Some variants show tunable pore sizes by adjusting linker length or node geometry. Mechanical stability and hydrolytic resistance are active areas of study.

Relation to other concepts: Pyramonal motifs overlap with broader families of porous crystalline materials, such as metal-organic frameworks and zeolites, but are distinguished by the emphasis on pyramid-shaped secondary building units and the resulting cavities.

History and terminology: The concept emerged in contemporary literature as a motif-based descriptor for certain structures; the term is used descriptively and is not tied to a single prototype compound. Ongoing research aims to formalize definitions and classification.