Barreto Wagner J, Barreto Sônia R G, Ando Rômulo A, Santos Paulo S, DiMauro Eduardo, Jorge Thiago
Laboratory of Environmental Physical Chemistry, Department of Chemistry, CCE, Londrina State University, Londrina, PR 86051-990, Brazil.
Spectrochim Acta A Mol Biomol Spectrosc. 2008 Dec 15;71(4):1419-24. doi: 10.1016/j.saa.2008.04.014. Epub 2008 Apr 30.
The anionic complexes Cu(L(1-))3, L(-)=dopasemiquinone or L-dopasemiquinone, were prepared and characterized. The complexes are stable in aqueous solution showing intense absorption bands at ca. 605 nm for Cu(II)-L-dopasemiquinone and at ca. 595 nm for Cu(II)-dopasemiquinone in the UV-vis spectra, that can be assigned to intraligand transitions. Noradrenaline and adrenaline, under the same reaction conditions, did not yield Cu-complexes, despite the bands in the UV region showing that noradrenaline and adrenaline were oxidized during the process. The complexes display a resonance Raman effect, and the most enhanced bands involve ring modes and particularly the nuCC+nuCO stretching mode at ca. 1384 cm(-1). The free radical nature of the ligands and the oxidation state of the Cu(II) were confirmed by the EPR spectra that display absorptions assigned to organic radicals with g=2.0005 and g=2.0923, and for Cu(II) with g=2.008 and g=2.0897 for L-dopasemiquinone and dopasemiquinone, respectively. The possibility that dopamine and L-dopa can form stable and aqueous-soluble copper complexes at neutral pH, whereas noradrenaline and adrenaline cannot, may be important in understanding how Cu(II)-dopamine crosses the cellular membrane as proposed in the literature to explain the role of copper in Wilson disease.
制备并表征了阴离子配合物[Cu(L⁻)₃]⁻，其中L⁻ = 多巴半醌或L - 多巴半醌。这些配合物在水溶液中稳定，在紫外可见光谱中，Cu(II)-L - 多巴半醌在约605 nm处、Cu(II)-多巴半醌在约595 nm处显示出强吸收带，这些吸收带可归因于配体内跃迁。在相同反应条件下，去甲肾上腺素和肾上腺素未生成铜配合物，尽管紫外区域的谱带表明去甲肾上腺素和肾上腺素在此过程中被氧化。这些配合物表现出共振拉曼效应，增强最明显的谱带涉及环模式，特别是约1384 cm⁻¹处的νCC + νCO伸缩模式。配体的自由基性质和Cu(II)的氧化态通过电子顺磁共振光谱得到证实，该光谱显示了分别对应于L - 多巴半醌和多巴半醌的g = 2.0005和g = 2.0923的有机自由基以及g = 2.008和g = 2.0897的Cu(II)的吸收。多巴胺和L - 多巴在中性pH下能够形成稳定的水溶性铜配合物，而去甲肾上腺素和肾上腺素则不能，这一可能性对于理解文献中提出的Cu(II)-多巴胺如何穿过细胞膜以解释铜在威尔逊病中的作用可能很重要。
