Department für Chemie, Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, D-50939 Köln, Germany.
Institute of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Beethovenstrasse 55, D-38106 Braunschweig, Germany.
Int J Mol Sci. 2021 Apr 12;22(8):3976. doi: 10.3390/ijms22083976.
The three complexes [Fe(opo)], [Cu(opo)], and [Zn(opo)] containing the non-innocent anionic ligand opo (opo = 9-oxido-phenalenone, Hopo = 9-hydroxyphenalonone) were synthesised from the corresponding acetylacetonates. [Zn(opo)] was characterised using H nuclear magnetic resonance (NMR) spectroscopy, the paramagnetic [Fe(opo)] and [Cu(opo)] by electron paramagnetic resonance (EPR) spectroscopy. While the EPR spectra of [Cu(opo)] and [Cu(acac)] in dimethylformamide (DMF) solution are very similar, a rather narrow spectrum was observed for [Fe(opo)] in tetrahydrofuran (THF) solution in contrast to the very broad spectrum of [Fe(acac)] in THF (Hacac = acetylacetone, 2,4-pentanedione; acac = acetylacetonate). The narrow, completely isotropic signal of [Fe(opo)] disagrees with a metal-centred = 5/2 spin system that is observed in the solid state. We assume spin-delocalisation to the opo ligand in the sense of an opo to Fe electron transfer. All compounds show several electrochemical opo-centred reduction waves in the range of -1 to -3 V vs. the ferrocene/ferrocenium couple. However, for Cu and Fe the very first one-electron reductions are metal-centred. Electronic absorption in the UV to vis range are due to π-π* transitions in the opo core, giving Hopo and [Zn(opo)] a yellow to orange colour. The structured bands ranging from 400 to 500 for all compounds are assigned to the lowest energy π-π* transitions. They show markedly higher intensities and slight shifts for the Cu (brown) and Fe (red) complexes and we assume admixing metal contributions (MLCT for Cu, LMCT for Fe). For both complexes long-wavelength absorptions assignable to d-d transitions were detected. Detailed spectroelectrochemical experiments confirm both the electrochemical and the optical assignments. Hopo and the complexes [Cu(opo)], [Zn(opo)], and [Fe(opo)] show antiproliferative activities against HT-29 (colon cancer) and MCF-7 (breast cancer) cell lines in the range of a few µM, comparable to cisplatin under the same conditions.
合成了三个包含非中性阴离子配体 opo（opo = 9-氧代菲咯酮，Hopo = 9-羟基菲咯酮）的配合物 [Fe(opo)]、[Cu(opo)] 和 [Zn(opo)]，其中 opo 来自相应的乙酰丙酮盐。[Zn(opo)] 用 H 核磁共振（NMR）光谱进行了表征，顺磁 [Fe(opo)] 和 [Cu(opo)] 用电子顺磁共振（EPR）光谱进行了表征。虽然 [Cu(opo)] 和 [Cu(acac)] 在二甲基甲酰胺（DMF）溶液中的 EPR 光谱非常相似，但 [Fe(opo)] 在四氢呋喃（THF）溶液中的光谱则相当窄，而 [Fe(acac)] 在 THF 中的光谱则非常宽（Hacac = 乙酰丙酮，2,4-戊二酮；acac = 乙酰丙酮盐）。[Fe(opo)] 的窄、完全各向同性信号与在固态中观察到的金属中心 = 5/2 自旋系统不一致。我们假设自旋离域到 opo 配体，即 opo 到 Fe 的电子转移。所有化合物在-1 至-3 V 相对于 ferrocene/ferrocenium 对的范围内都显示出几个电化学 opo 中心还原波。然而，对于 Cu 和 Fe，第一个单电子还原是金属中心的。在紫外至可见光范围内的电子吸收归因于 opo 核中的 π-π跃迁，使 Hopo 和 [Zn(opo)] 呈现黄色到橙色。所有化合物的 400 至 500nm 范围内的结构带归因于最低能量的 π-π跃迁。它们的强度明显更高，Cu（棕色）和 Fe（红色）配合物的位移也略有增加，我们假设混合了金属贡献（Cu 为 MLCT，Fe 为 LMCT）。两个配合物都检测到可归因于 d-d 跃迁的长波长吸收。详细的光谱电化学实验证实了电化学和光学的分配。Hopo 和配合物 [Cu(opo)]、[Zn(opo)] 和 [Fe(opo)] 在几 µM 的范围内对 HT-29（结肠癌）和 MCF-7（乳腺癌）细胞系表现出抗增殖活性，与相同条件下的顺铂相当。
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