Synthesis, X-ray structure and ascorbic oxidation properties of ternary α-amino acid Schiff base-bipy Cu(II) complexes as functional models for ascorbic oxidase
Synthesis, X-ray structure and ascorbic oxidation properties of ternary α-amino acid Schiff base-bipy Cu(II) complexes as functional models for ascorbic oxidase
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DOI：
10.1016/j.poly.2013.01.020
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发表时间：
2013-04-10
期刊：
影响因子：
2.6
通讯作者：
Notash, Behrouz
中科院分区：
文献类型：
--
作者：
Moradi-Shoeili, Zeinab;Amini, Zahra;Notash, Behrouz
三个三元铜 (II) 配合物 [Cu(5-bromo-salTyr)(bipy)] 中心点 1/2CH(3)OH (1)、[Cu(5-bromo-salLue)(bipy)] 中心点 CH3OH (2) 和 [Cu(5-bromo-salTrp)(bipy)] 中心点 3CH(3)OH (3)（其中 5-bromo-salTyr， 5-bromo-salLue和5-bromo-salTrp是由5-溴水杨醛分别与酪氨酸、亮氨酸和色氨酸缩合得到的三齿席夫碱配体，bipy是2,2'-联吡啶，已制备并通过元素分析、电子、红外光谱、磁测量和循环伏安法进行表征。配合物 1 和 3 也已通过 X 射线衍射技术进行了结构表征。配合物 1 和 3 的晶体结构在 Cu(II) 周围呈现出扭曲的方锥体几何形状。该配合物具有单电子顺磁性，在甲醇水溶液中分别在 664 nm 和 378 nm 附近显示出 1 个 d-d 跃迁和 1 个 LMCT 谱带。 1-3 在 DMF 介质中的电化学研究显示出在 -0.3 至 0.5 V 电位范围内的不可逆 Cu(II)/Cu(I) 氧化还原电对以及与约 0.8 V 配体氧化相关的附加不可逆阳极波。这些配合物在分子氧存在下对抗坏血酸的氧化也具有催化活性，模拟了抗坏血酸氧化酶中 Cu(II) 位点的抗坏血酸氧化特性。该催化循环对于1-3的[H(2)A]:[络合物]摩尔比为约100是有效的。 (C) 2013 Elsevier Ltd. 保留所有权利。
Three ternary copper(II) complexes [Cu(5-bromo-salTyr)(bipy)]center dot 1/2CH(3)OH (1), [Cu(5-bromo-salLue)(bipy)]center dot CH3OH (2) and [Cu(5-bromo-salTrp)(bipy)]center dot 3CH(3)OH (3) (where 5-bromo-salTyr, 5-bromo-salLue and 5-bromo-salTrp are tridentate Schiff base ligands derived from the condensation of 5-bromosalicylaldehyde with tyrosine, leucine and tryptophan, respectively, and bipy is 2,2'-bipyridine) have been prepared and characterized by elemental analysis, electronic, IR spectroscopies, magnetic measurement and cyclic voltammetry. The complexes, 1 and 3 have been also structurally characterized by X-ray diffraction technique. Crystal structures of 1 and 3 complexes displayed a distorted square-pyramidal geometry around Cu(II). The complexes are one-electron paramagnetic and show one d-d transition and one LMCT bands near 664 and 378 nm in aqueous methanol, respectively. The electrochemical studies of 1-3 in DMF medium exhibit an irreversible Cu(II)/Cu(I) redox couple in the potential range of -0.3 to 0.5 V and one additional irreversible anodic wave associated with oxidation of ligands about 0.8 V. These complexes are also catalytically active in oxidation of ascorbic acid in presence of dioxygen, models the ascorbate oxidation property of the Cu(II) sites in ascorbate oxidase. The catalytic cycle is effective for a [H(2)A]:[complex] mole ratio of about 100 for 1-3. (C) 2013 Elsevier Ltd. All rights reserved.