Metallimidazolates

Metallimidazolates are coordination compounds and materials in which metal ions or clusters are linked by imidazolate ligands, the deprotonated form of imidazole. They encompass discrete metal-imidazolate complexes as well as extended networks such as metal-organic frameworks.

In these systems the imidazolate ligand typically bridges two or more metal centers through its nitrogen atoms, generating M–Im–M motifs. Common metals include Zn, Cu, Co, Ni, Fe, and Mn, with Zn and transition metals forming robust frameworks. A well-known subfamily is the zeolitic imidazolate frameworks (ZIFs), exemplified by Zn(mIm)2, which adopt porous, tetrahedrally coordinated metal centers and cagelike networks.

Synthesis often involves reaction of a metal salt with imidazole or its derivatives under solvothermal or hydrothermal conditions; deprotonation to imidazolate is promoted by base or modulators. Similar chemistry yields discrete clusters as well as extended 2D or 3D frameworks; solubility and kinetics influence crystallinity and porosity.

Characteristics include high thermal and chemical stability, tunable pore structures, and substantial surface areas, enabling applications in gas storage and separation, catalysis, and sensing. Some metallimidazolates show catalytic activity in acid-base or oxidation reactions, and certain frameworks exhibit interesting magnetic or electronic properties.

Notable examples encompass ZIF-8 and related ZIFs, which have found industrial and research use, as well as other metallimidazolates with different metal centers and imidazole derivatives.