Understanding DNA-ligand interactions is a prerequisite, for designing sequence/structure specific ligands. Generally, stabilization/destabilization of DNA structures as a function of ligand is studied using UV-thermal melting, and the data is usually interpreted by observing the hyperchromicity of DNA alone, without considering any contribution from free ligand. Herein, a temperature dependent hyperchromicity is reported for an antitumor drug Coralyne, in unbound state. The self-association has been investigated by UV-Visible absorption spectroscopy, UV- thermal melting and high resolution ¹H NMR. NMR spectra depict temperature dependent down field shifts of aromatic ring protons indicating self-association of Coralyne at 277 K, possibly stabilized by stacking of four aromatic rings. Following this data, it is suggested to have a detailed information on the solution state of the free ligand, before performing DNA interaction studies. To the best of our knowledge, temperature dependent hyperchromism of Coralyne has not been reported till date. Kindly incorporate Graphical Abstract

了解DNA-配体相互作用是设计序列/结构特异性配体的前提。通常，使用紫外线-热熔解法研究DNA结构作为配体的稳定/去稳定作用，通常仅通过观察DNA的高色性来解释数据，而不考虑游离配体的任何贡献。在本文中，报道了未结合状态的抗肿瘤药物Coralyne的温度依赖性增色性。通过紫外可见吸收光谱，紫外热熔融和高分辨率研究了自缔合¹1 H NMR。NMR谱图描绘了取决于温度的芳环质子下降场位移，表明Coralyne在277 K处自缔合，可能通过四个芳环的堆叠来稳定。根据这些数据，建议在进行DNA相互作用研究之前，先获得有关游离配体溶液状态的详细信息。据我们所知，到目前为止，尚未报道Coralyne的温度依赖性增色现象。请加入图形摘要