multicarboxylates

Multicarboxylates are chemical species that contain two or more carboxylate groups (−COO−) within a single molecule. They can refer to dianions, trianions, or higher-charge forms derived from polybasic carboxylic acids, as well as their ester derivatives. In aqueous solution, the carboxylate groups can be deprotonated to different extents depending on pH, giving rise to varied coordination and buffering properties. Multicarboxylates are especially important as ligands in coordination chemistry, where multiple carboxylate sites enable binding to metal ions and formation of chelates or polynuclear complexes.

Key examples include oxalate (ethanedioate), malonate (propane-1,3-dioate), succinate (butane-1,4-dioate), and glutarate (pentane-1,5-dioate) among dicarboxylates, as well as citrate (tricarboxylate). In synthetic chemistry, polycarboxylates serve as building blocks for polyesters and other carboxylate-containing polymers. A well-known ligand is EDTA (ethylenediaminetetraacetate), which contains four carboxylate groups and two amine nitrogens, and binds metal ions in multiple coordination modes. Many natural multicarboxylates, such as citrate, malate, and isocitrate, play roles in metabolism, notably in the citric acid cycle.

Applications and significance of multicarboxylates include their use as chelating agents in water treatment and detergents, as food additives and pharmaceuticals, and as components in specialized polymers. Their ability to bind metal ions affects metal availability in ecological systems and can influence processes ranging from soil chemistry to mineral scaling.