NDLI: Synthesis, spectroscopy, and binding constants of ketocatechol-containing iminodiacetic acid and its Fe(III), Cu(II), and Zn(II) complexes and reaction of Cu(II) complex with $H_{2}O

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Bai, Yueling Xing, Feifei Zhu, Shourong Gao, Jiaojiao
Description	Author Affiliation: Gao J ( Department of Chemistry, Innovative Drug Research Center, Shanghai University, Shanghai 200444, China. shourongzhu@shu.edu.cn xff@shu.edu.cn.)
Abstract	A new neuromelanin-like ketocatechol-containing iminodiacetic acid ligand, (N-(3,4-dihydroxyl)phenacylimino)diacetic acid $(H_{4}L),$ which is also quite similar to compounds found in insect cuticle, has been synthesized and characterized. The X-ray crystal structure of $H_{4}L$ has been successfully determined. Proton binding and coordination with Fe(III), Cu(II), and Zn(II) have been studied by potentiometric titrations and UV-vis spectrophotometry in aqueous solution. UV spectra of $H_{4}L$ in the absence and presence of different metal ions indicate complexes formed with the catechol moiety of $H_{4}L$ in aqueous solution. Visible spectra and NMR reveal that $H_{4}L$ with Fe(III), Cu(II), and Zn(II) can all give stable mono-(ML) and dinuclear complexes [M(ML)]. Fe(III) can also form $\{Fe(FeL)_{2}\}$ and $\{Fe(FeL)_{3}\}$ species with sufficient base. The process is accompanied by a drastic color change from light blue to deep-blue to wine-red. The Fe(III)–Cu(II) heteronuclear complex also exists in aqueous solution whose spectra are similar to the homonuclear Fe(III) complex. However, the spectra of {Fe(CuL)} shifted to a longer wavelength and $\{Fe(CuL)_{2}\}$ and $\{Fe(CuL)_{3}\}$ shifted to a shorter wavelength. Keto–enol tautomerism was observed in weak basic aqueous solution as indicated by $^{1}H$ NMR spectra. The reaction products of Cu(II) complex with $H_{2}O_{2}$ depend on the $H_{2}O_{2}$ concentration and pH value. Low concentrations of $H_{2}O_{2}$ oxidize $H_{4}L$ to a series of semiquinone and quinone compounds with absorption maxima at 314–400 nm, while a high concentration of $H_{2}O_{2}$ oxidizes $H_{4}L$ to colorless muconic acid derivatives. $NaIO_{4}$ gives different oxidase products, but no 2,4,5-trihydroxyphenylalanine quinone (TPQ)-like hydroxyquinone can be found.
ISSN	14779226
Issue Number	21
Volume Number	43
e-ISSN	13645447
Journal	Dalton Trans.
Language	English
Publisher	Royal Society of Chemistry
Publisher Date	2014-06-07
Publisher Place	Great Britain (UK)
Access Restriction	Subscribed
Subject Keyword	Catechols Chemistry Coordination Complexes Copper Ferric Compounds Hydrogen Peroxide Imino Acids Zinc Chemical Synthesis Crystallography, X-Ray Magnetic Resonance Spectroscopy Models, Molecular Oxidation-Reduction Spectrophotometry, Ultraviolet Water Journal Article Research Support, Non-U.S. Gov't
Content Type	Text
Resource Type	Article
Subject	Inorganic Chemistry

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