Wirtsatomen

Wirtsatomen, literally "host atoms" in German, describes the atoms that form the host framework in host–guest systems. The host provides cavities, channels, or interstices that accommodate guest species such as molecules, ions, or small atoms. Thus Wirtsatomen define the structural backbone of materials such as zeolites, metal–organic frameworks (MOFs), covalent organic frameworks (COFs), and clathrates.

In zeolites and silica-based networks, Wirtsatomen are typically metal cations linked to silicon or aluminum through oxygen, forming a three-dimensional aluminosilicate framework. In MOFs and COFs, metal nodes or covalent linkages shape the porous host, while organic linkers or ligands create the pore network. The identity and connectivity of Wirtsatomen determine pore size, surface area, and the chemical environment that governs guest interactions.

Guest species—gases, liquids, or ions—occupy the cavities and interact with Wirtsatomen via adsorption, coordination, hydrogen bonding, or van der Waals forces. The study of Wirtsatomen informs diffusion, framework stability, and selectivity in separations and catalysis. Characterization methods include X-ray and neutron diffraction, spectroscopy, and computational modeling.

Applications include gas storage and separation, heterogeneous catalysis, sensing, and drug delivery systems based on inclusion within a host lattice. See also host–guest chemistry, zeolites, MOFs, and clathrate hydrates.