Metallocarboxypeptidases

Metallocarboxylates are compounds in which a metal center is coordinated by carboxylate ligands derived from carboxylic acids. They encompass discrete metal carboxylate complexes as well as extended networks such as coordination polymers and metal-organic frameworks. The carboxylate ligand can bind in multiple modes, including terminal bidentate and various μ-bridging arrangements, generating diverse structures across the periodic table.

Bonding and structure commonly involve strong M–O bonds formed by the carboxylate group. Bridging modes enable the formation of polynuclear cores and three-dimensional networks in many samples. Infrared spectroscopy often reveals characteristic carboxylate stretches whose patterns reflect the binding mode, helping distinguish bridged versus terminal coordination.

Synthesis and occurrence typically proceed by reacting a metal salt or oxide with a carboxylate source, such as a sodium or ammonium carboxylate, or by direct salt metathesis with carboxylic acid salts. These reactions can be conducted in solution or under solvothermal/hydrothermal conditions to yield crystalline materials. Metallocarboxylates are common across alkali, alkaline earth, transition, and lanthanide families, with stability and reactivity depending on the metal and the particular carboxylate.

Properties and applications vary widely but many metallocarboxylates are sparingly soluble in water and their behavior is strongly influenced by the metal center. They serve as catalysts or precursors in polymerization and oxidation reactions, as stabilizers and additives in polymers, and as precursors to metal oxides upon heating. Notable examples include calcium acetate, zinc stearate, and aluminum octoate.

In materials chemistry, metal carboxylate motifs are central to metal-organic frameworks and coordination polymers, where carboxylate linkers connect metal nodes to form porous, crystalline structures.