Two chiral Ru(II) polypyridyl complexes, Δ-[Ru(bpy)₂(6-F-dppz)]²⁺ (Δ-1; bpy = 2,2′-bipyridine, 6-F-dppz = 6-fluorodipyrido[3,2-a:2′,3′-c]phenazine) and Λ-[Ru(bpy)₂(6-F-dppz)]²⁺ (Λ-1), have been synthesized and characterized as binders for the RNA poly(U)•poly(A)*poly(U) triplex and poly(A)•poly(U) duplex in this work. Analysis of the UV–Vis absorption spectra and fluorescence emission spectra indicates that the binding of intercalating Δ-1 with the triplex and duplex RNA is greater than that of Λ-1, while the binding affinities of the two enantiomers to triplex structure is stronger than that of duplex structure. Fluorescence titrations show that the two enantiomers can act as molecular “light switches” for triple- and double-helical RNA. Thermal denaturation studies revealed that that the two enantiomers are more stable to Watson-Crick base-paired double strand of the triplex than the Hoogsteen base-paired third strand, but their stability and selectivity are different. For Δ-enantiomer, the increase of the thermal stability of the Watson-Crick base-paired duplex (13 °C) is slightly stronger than of the Hoogsteen base-paired strand (10 °C), displaying no obvious selectivity. However, compared to the Hoogsteen base-paired strand (5 °C), the stability of the Λ-enantiomer to the Watson-Crick base-paired duplex (13 °C) is more significant, which has obvious selectivity. The overall increase in viscosity of the RNA-(Λ-1) system and its curve shape are similar to that of the RNA-(Δ-1) system, suggesting that the binding modes of two enantiomers with RNA are intercalation. The obtained results in this work may be useful for understanding the binding differences in chiral Ru(II) polypyridyl complexes toward RNA triplex and duplex.

两个手性 Ru(II) 多吡啶基配合物，Δ-[Ru(bpy) ₂ (6-F-dppz)] ²⁺ (Δ- 1 ; bpy = 2,2'-联吡啶，6-F-dppz = 6-氟联吡啶[3,2- a :2',3'- c ]吩嗪)和Λ-[Ru(bpy) ₂ (6-F-dppz)] ²⁺ (Λ- 1 )，已被合成并表征为RNA poly(U)•poly(A)*poly(U)三链体和poly(A)•poly(U)双链体。UV-Vis吸收光谱和荧光发射光谱的分析表明，插入Δ- 1与三链体和双链体RNA的结合大于Λ- 1，而两种对映体对三链结构的结合亲和力强于双链结构。荧光滴定表明，这两种对映异构体可以作为三螺旋和双螺旋 RNA 的分子“光开关”。热变性研究表明，这两种对映体对三链体的 Watson-Crick 碱基配对双链比 Hoogsteen 碱基配对第三链更稳定，但它们的稳定性和选择性不同。对于 Δ-对映异构体，Watson-Crick 碱基配对双链体 (13 °C) 的热稳定性增加略强于 Hoogsteen 碱基配对链 (10 °C)，没有显示出明显的选择性。然而，与 Hoogsteen 碱基配对链 (5 °C) 相比，Λ-对映异构体对 Watson-Crick 碱基配对双链体 (13 °C) 的稳定性更显着，具有明显的选择性。RNA-(Λ- 1 ) 系统及其曲线形状与RNA-(Δ- 1 ) 系统相似，表明两种对映异构体与RNA的结合方式为嵌入。在这项工作中获得的结果可能有助于理解手性 Ru(II) 多吡啶复合物对 RNA 三链体和双链体的结合差异。