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首页> 外文期刊>Journal of the Indian Chemical Society >Mixed-ligand complex formation equilibria of Cu~(II) with histidine and biguanide
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Mixed-ligand complex formation equilibria of Cu~(II) with histidine and biguanide

机译:Cu〜(II)与组氨酸和双胍的混合配体络合物形成平衡

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Combined spectrophotometry and computer-based pH-metric investigations on the mixed-ligand complex formation equilibria of Cu~(II) with histidine [(C3H3N2)CH2CH(NH2)COOH, hisH~±] and biguanide [NH2C-(=NH)NHC(=NH)NH2, Bg] in aqueous solution at a constant ionic strength (I= 0.1 mol dm~(-3)) and 25 ± 1°C, provided evidence of binary [Cu(hism)~+], [Cu(hism-H)], [CuChism)2], [Cu(hism)(hism-H)~-], [Cu(hism-H)_2~(2-)] and [Cu(Bg)~(2+)] and ternary [Cu(hism)(Bg)~+], [Cu(hism-H)(Bg)], [Cu(Bg)(OH)~+] and [Cu(Bg-H)(OH)] complexes, Histidine provides both histamine-like [(NH2, N-imidazole i.e. (hism-)] and mixed histamine-like glycine-like [(NH2, N-imidazole) (NH2, COO~-) i.e. (hism~-)(gly~-] chelation, barring simple glycine-like (gly~-) chelation. Binding affinity of Cu~(II) for (NH2, =NH) bidentate chelating biguanide is so strong that the histidine-imidazole deprotonated mixed-ligand complex, [Cu(hism-H)(Bg)] decomposes at pH > 10 to biguanide (=NH) deprotonated ternary hydroxo complex, [Cu(Bg-H)(OH)], setting free the his" ligand ion in solution, a phenomenon of great biological significance, in regard to medicinal applications of the title ligands and their metal derivatives.
机译:分光光度法和基于计算机的pH计量研究Cu〜(II)与组氨酸[(C3H3N2)CH2CH(NH2)COOH,hisH〜±]和双胍[NH2C-(= NH)NHC的混合配体络合物形成平衡(= NH)NH2,Bg]在恒定离子强度(I = 0.1 mol dm〜(-3))和25±1°C的水溶液中,提供了二元[Cu(hism)〜+],[Cu (hism-H)],[CuChism)2],[Cu(hism)(hism-H)〜-],[Cu(hism-H)_2〜(2-)]和[Cu(Bg)〜(2 +)]和三元[Cu(hism)(Bg)〜+],[Cu(hism-H)(Bg)],[Cu(Bg)(OH)〜+]和[Cu(Bg-H)(OH) )]组氨酸提供了组胺样[[NH2,N-咪唑((hism-)]]和混合的组胺样甘氨酸样[[NH2,N-咪唑)(NH2,COO〜-)即(hism〜 -)(gly〜-]螯合,禁止简单的甘氨酸样(gly〜-)螯合。Cu〜(II)与(NH2,= NH)二齿螯合双胍的结合亲和力很强,以至组氨酸-咪唑去质子化的混合-配体配合物[Cu(hism-H)(Bg)]在pH> 10时分解为双胍(= NH)去质子化的三元羟基配合物[Cu(B g-H)(OH)],就标题配体及其金属衍生物的医学应用而言,在溶液中释放出His'配体离子,这是一种具有重大生物学意义的现象。

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