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|Section2= |Section3= |Section7= |Section8= }} Pentetic acid or diethylene triamine pentaacetic acid (DTPA) is an aminopolycarboxylic acid consisting of a diethylenetriamine backbone with five carboxymethyl groups. The molecule can be viewed as an expanded version of EDTA and is used similarly. It is a white, water-soluble solid. ==Coordination properties== The conjugate base of DTPA has a high affinity for metal cations. Thus, the penta-anion DTPA5− is potentially an octadentate ligand assuming that each nitrogen centre and each COO−-group counts as a centre for coordination. The formation constants for its complexes are about 100 greater than those for EDTA.〔J. Roger Hart "Ethylenediaminetetraacetic Acid and Related Chelating Agents" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.〕 As a chelating agent, DTPA wraps around a metal ion by forming up to eight bonds. Transition metals, however, usually form less than eight coordination bonds. So, after forming a complex with a metal, DTPA still has the ability to bind to other reagents, as is shown by its derivative pendetide. For example, in its complex with copper(II), DTPA binds in a hexadentate manner utilizing the three amine centres and three of the five carboxylates.〔V. V. Fomenko, T. N. Polynova, M. A. Porai-Koshits, G. L. Varlamova and N. I. Pechurova ''Crystal structure of copper (II) diethylenetriaminepentaacetate monohydrate'' Journal of Structural Chemistry, 1973, Vol. 14, 529. 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pentetic acid」の詳細全文を読む スポンサード リンク
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