iminodiacetic

Iminodiacetic acid, commonly abbreviated IDA, is an aminopolycarboxylic acid that functions as a chelating agent. The molecule is organized around an imino linkage that connects two acetic acid moieties, giving it the ability to bind metal ions through donor atoms on the amine nitrogen and the two carboxylate groups.

In terms of coordination chemistry, iminodiacetic acid typically acts as a tridentate ligand, coordinating a metal ion via one nitrogen atom and two carboxylate oxygen atoms. Depending on the pH, the ligand can be present in mono-, di-, or tri-deprotonated forms, which influences its binding strength and the geometry of the resulting metal complex. The resulting chelate rings and donor set give IDA complexes stability with a variety of metal ions, including transition metals and some post-transition metals.

Industrial and practical uses of iminodiacetic acid arise largely from its role in chelating resins and analytical chemistry. IDA-functionalized resins are employed in water treatment and metal ion separations to remove and recover divalent and trivalent metals. In analytical and preparative chemistry, IDA and its derivatives serve as ligands in complexometric titrations, chromatography, and metal ion purification.

IDA is related to other aminopolycarboxylate chelating agents, such as nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid (EDTA), but it offers a simpler, tridentate binding framework that can be advantageous for certain separations and binding selectivities. Care should be taken in handling, as with many chelating agents, due to their potential to sequester essential metal ions.