An Electrochemical Study of Antineoplastic Gallium, Iron and Ruthenium Complexes with Redox Noninnocent α-N-Heterocyclic Chalcogensemicarbazones
An Electrochemical Study of Antineoplastic Gallium, Iron and Ruthenium Complexes with Redox Noninnocent α-N-Heterocyclic Chalcogensemicarbazones
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DOI：
10.1021/ic8013249
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发表时间：
2008-12-01
影响因子：
4.6
通讯作者：
Keppler, Bernhard K.
中科院分区：
文献类型：
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作者：
Kowol, Christian R.;Reisner, Erwin;Keppler, Bernhard K.
一系列α-N-杂环硫属缩氨基脲(HL)，即缩氨基硫脲、硒代缩氨基脲和缩氨基脲，以及它们的镓(III)、铁(III)和钌(III)络合物，通式为[ML2][Y]（M = Ga、Fe或Ru；Y = PF6-、NO3-或FeCl4-)通过循环伏安法进行研究。通过元素分析、多种光谱方法（NMR、UV-vis、IR）、质谱和 X 射线晶体学对新型化合物进行了表征。所有配合物都显示出几种大多是可逆的氧化还原波，这归因于有机电解质溶液中非无害的硫属缩氨基脲配体在较低电势（0 V vs NHE）下的还原。镓配合物的循环伏安图显示至少两个连续的可逆单电子还原波。这些还原在相应的铁和钌配合物中移动了大约 0.6 V 至较低的电势。电化学、化学和光谱数据表明以配体为中心的还原发生在 CH3C=N 双键处。对 2-乙酰基吡啶 N-4,N-4-二甲基缩氨基硫脲 (HLB)、相应金属配合物 [Ga(L-B)(2)](+) 和 [FeII(L-B)(2)] 以及这些物质的单电子还原产物的几何和电子结构的量子化学计算支持还原位点的分配并阐明了以配体为中心的氧化还原电位的观察顺序， E-1/2([Fe-II(L)(2)]) < E-1/2(HL) < E-1/2([Ga(L)(2)](+))。报道了水对复合物氧化还原电位的影响，并讨论了电化学数据与细胞毒性以及核糖核苷酸还原酶抑制能力的生理相关性。
The electrochemical properties of a series of alpha-N-heterocyclic chalcogensemicarbazones (HL), namely, thiosemicarbazones, selenosemicarbazones, and semicarbazones, and their gallium(III), iron(III), and ruthenium(Ill) complexes with the general formula [ML2][Y] (M = Ga, Fe or Ru; Y = PF6-, NO3-, or FeCl4-) were studied by cyclic voltammetry. The novel compounds were characterized by elemental analysis, a number of spectroscopic methods (NMR, UV-vis, IR), mass spectrometry and by X-ray crystallography. All complexes show several, mostly reversible, redox waves attributable to the reduction of the noninnocent chalcogensemicarbazone ligands at lower potentials (0 V vs NHE) in organic electrolyte solutions. The cyclic voltammograms of the gallium complexes display at least two consecutive reversible one-electron reduction waves. These reductions are shifted by similar to 0.6 V to lower potentials in the corresponding iron and ruthenium complexes. The electrochemical, chemical, and spectroscopic data indicate that the ligand-centered reduction takes place at the CH3C=N double bond. Quantum chemical calculations on the geometric and electronic structures of 2-acetylpyridine N-4,N-4-dimethylthiosemicarbazone (HLB), the corresponding metal complexes [Ga(L-B)(2)](+) and [FeII(L-B)(2)], and the one-electron reduction product for each of these species support the assignment of the reduction site and elucidate the observed order of the ligand-centered redox potentials, E-1/2([Fe-II(L)(2)]) < E-1/2(HL) < E-1/2([Ga(L)(2)](+)). The influence of water on the redox potentials of the complexes is reported and the physiological relevance of the electrochemical data for cytotoxicity as well as for ribonucleotide reductase inhibitory capacity are discussed.