Two new complexes based on pipemidic acid (HPPA) and Co²⁺/Cd²⁺ ions, [Co(PPA)₂]·2H₂O (1) and Cd(PPA)₂ (2), have been synthesized and structurally characterized. Single-crystal X-ray diffraction analysis shows that complexes 1 and 2 exhibit similar structures containing two-fold meso-helices and 1D supramolecular channels. The interaction of calf-thymus (CT-DNA) with complexes 1 and 2 with was explored by UV spectrum, and competitive studies with ethidium bromide (EB) by fluorescence spectrum. Notably, these results indicate that complexes 1 and 2 possess the higher binding DNA affinity than free HPPA drugs, maybe attributed to the coordinated metal ions and the helical channels. And the resultant hypochromism suggests the tight binding of 1 and 2 with CT-DNA probably by the intercalative mode. Moreover, the relatively high Ksv value also indicates that 1 and 2 can bind to CT-DNA for the intercalative binding sites.

Graphic Abstract

Two new complexes based on HPPA were synthesized and structural description, and exhibit similar structures containing two-fold meso-helices. The result of the interaction with CT-DNA indicates that complexes can bind to the CT-DNA by the intercalative mode and possess the higher binding constant to CT-DNA than free HPPA drugs.

中文翻译：

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两种包含螺旋通道的喹诺酮金属配合物的结构及其与CT-DNA的相互作用

合成了两种基于哌啶酸（HPPA）和Co ²⁺ / Cd ²⁺离子的新配合物[Co（PPA）₂ ]·2H ₂ O（1）和Cd（PPA）₂（2）。 。X射线单晶衍射分析表明，配合物1和2表现出相似的结构，其中包含两个中观螺旋和一维超分子通道。小牛胸腺的相互作用通过紫外光谱探索了配合物1和2与（CT-DNA）的结合，并通过荧光光谱与溴化乙锭（EB）进行了竞争性研究。值得注意的是，这些结果表明，复合物1和2具有比游离HPPA药物更高的结合DNA亲和力，这可能归因于配位的金属离子和螺旋通道。并且由此产生的色差表明1和2与CT-DNA的紧密结合可能是通过插入模式实现的。此外，相对较高的Ksv值也表明1和2可以结合CT-DNA的插入结合位点。

图形摘要

合成了两种基于HPPA的新配合物，并进行了结构描述，显示出相似的结构，其中包含两个中观螺旋。与CT-DNA相互作用的结果表明，复合物可以通过插入模式与CT-DNA结合，并且与游离HPPA药物相比，具有更高的与CT-DNA的结合常数。