Electronic effect of different positions of the –NO2 group on the DNA-intercalator of chiral complexes [Ru(bpy)2L]2+(L =o-npip, m-npip and p-npip)
作者:Shuo Shi、Jie Liu、Jun Li、Kang C. Zheng、Cai P. Tan、Lan M. Chen、Liang N. Ji
DOI:10.1039/b501112d
日期:——
New chiral Ru(II) complexes with intercalators L (L =
o-npip, m-npip and p-npip) containing âNO2 at different positions on the phenyl ring were synthesized and characterized by elemental analysis, 1H NMR, ESI-MS and CD spectra. The DNA binding properties of these complexes have been investigated with UV-Vis, emission spectra, CD spectra and viscosity measurements. A subtle but detectable difference was observed in the interaction of these isomers with CT-DNA. Absorption spectroscopy experiments indicated that each of these complexes can interact with the DNA. The DNA-binding of the Î-isomer is stronger than that of Î-isomer. DNA-viscosity experiments provided evidence that both Î- and Î-[Ru(bpy)2(o-npip)](PF6)2 bind to DNA with partial intercalation, and both Î- and Î-[Ru(bpy)2(p-npip)](PF6)2 fully intercalate with DNA. However, Î- and Î- [Ru(bpy)2(m-npip)](PF6)2 bind to DNA through different modes, i.e., the Î isomer by intercalation and Î isomer by partial intercalation. Under irradiation with UV light, Ru(II) complexes showed different efficiency of cleaving DNA. The most interesting feature is that neither 1
(Î-1 and Î-1) nor 3
(Î-3 and Î-3) emit luminescence either alone in aqueous solution or in the presence of DNA, whereas both Î-2 and Î-2 emit luminescence under the same conditions. In addition, theoretical calculations for these three isomer complexes have been carried out applying the density functional theory (DFT) method at the level of the B3LYP/LanL2DZ basis set, and the calculated results can reasonably explain the obtained experimental trends in the DNA-binding affinities or binding constants (Kb) and some spectral properties of the complexes.
通过元素分析、1H NMR、ESI-MS 和 CD 光谱,合成并表征了在苯环不同位置含有 âNO2 的插入剂 L(L = o-npip、m-npip 和 p-npip)的新型手性 Ru(II) 复合物。通过紫外可见光谱、发射光谱、CD 光谱和粘度测量,研究了这些复合物的 DNA 结合特性。在这些异构体与 CT-DNA 的相互作用中观察到了微妙但可检测到的差异。吸收光谱实验表明,这些复合物都能与 DNA 发生作用。δ异构体的 DNA 结合力强于δ异构体。DNA 粘度实验证明,δ和δ-[Ru(bpy)2(o-npip)](PF6)2 与 DNA 的结合都是部分插层,而δ和δ-[Ru(bpy)2(p-npip)](PF6)2 与 DNA 的结合都是完全插层。但是,δ-和δ-[Ru(bpy)2(m-npip)](PF6)2 与 DNA 的结合方式不同,即δ异构体通过插层结合,而δ异构体通过部分插层结合。在紫外线照射下,Ru(II)配合物对 DNA 的裂解效率各不相同。最有趣的特征是,1(δ-1 和 δ-1)和 3(δ-3 和 δ-3)单独在水溶液中或在 DNA 存在的情况下都不会发光,而 δ-2 和 δ-2 在相同条件下都会发光。此外,我们还采用密度泛函理论(DFT)方法,在 B3LYP/LanL2DZ 基集水平上对这三种异构体配合物进行了理论计算,计算结果可以合理地解释所获得的配合物在 DNA 结合亲和力或结合常数(Kb)以及某些光谱特性方面的实验趋势。