Interaction of Imidazole Containing Hydroxamic Acids with Fe(III): Hydroxamate Versus Imidazole Coordination of the Ligands
Interaction of Imidazole Containing Hydroxamic Acids with Fe(III): Hydroxamate Versus Imidazole Coordination of the Ligands
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含异羟肟酸的咪唑与 Fe(III) 的相互作用：异羟肟酸盐与配体的咪唑配位
DOI：
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发表时间：
2007
影响因子：
3.8
通讯作者：
N. Nagy
中科院分区：
文献类型：
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作者：
E. Farkas;D. Bátka;H. Csóka;N. Nagy
用pH电位法、紫外可见分光光度法、EPR、ESI-MS和H1-NMR等方法研究了咪唑-4-羧异羟肟酸（Im-4-Cha）、N-甲基咪唑-4-羧异羟肟酸（N-Me-Im-4-Cha）、咪唑-4-乙酰异羟肟酸（Im-4-Aha）和组氨酸异羟肟酸（Hisha）与Fe（III）形成的配合物的溶液平衡。所有得到的结果表明，咪唑部分能够发挥重要的作用，经常在与Fe（III）的相互作用，即使这种金属离子更喜欢异羟肟酸螯合物非常多。如果咪唑部分位于异羟肟酮的α位（Im-4-Cha和N-Me-Im-4-Cha），则其与金属离子的配位由我们的结果明确地指示。有趣的是，（Nimidazole，Ohydroxamate）和（Ohydroxamate，Ohydroxamate）型螯合物的平行形成似乎可能与N-Me-Im-4-Cha。咪唑位于Im-4-Aha中异羟肟基的β-位，分子间的非共价（主要是氢键）相互作用似乎将该体系中的中间体质子化分子组织起来。形成后的单和bishydroxamato单核复合物，只有EPR沉默物种存在于Fe（III）-Hisha系统pH 4以上，这表明相当显着的“组装活性”的咪唑（也许连同铵部分）。
Solution equilibrium studies on Fe(III) complexes formed with imidazole-4-carbohydroxamic acid (Im-4-Cha), N-Me-imidazole-4-carbohydroxamic acid (N-Me-Im-4-Cha), imidazole-4-acetohydroxamic acid (Im-4-Aha), and histidinehydroxamic acid (Hisha) have been performed by using pH-potentiometry, UV-visible spectrophotometry, EPR, ESI-MS, and H1-NMR methods. All of the obtained results demonstrate that the imidazole moiety is able to play an important role very often in the interaction with Fe(III), even if this metal ion prefers the hydroxamate chelates very much. If the imidazole moiety is in α-position to the hydroxamic one (Im-4-Cha and N-Me-Im-4-Cha) its coordination to the metal ion is indicated unambiguously by our results. Interestingly, parallel formation of (Nimidazole, Ohydroxamate), and (Ohydroxamate, Ohydroxamate) type chelates seems probable with N-Me-Im-4-Cha. The imidazole is in β-position to the hydroxamic moiety in Im-4-Aha and an intermolecular noncovalent (mainly H-bonding) interaction seems to organize the intermediate-protonated molecules in this system. Following the formation of mono- and bishydroxamato mononuclear complexes, only EPR silent species exists in the Fe(III)-Hisha system above pH 4, what suggests the rather significant “assembler activity” of the imidazole (perhaps together with the ammonium moiety).