A new polymorph of six-coordinated bis(5,5′-dimethyl-2,2′-bipyridine) nitratocopper(II) nitrate and its DNA interactions

•A new polymorph of Cu(II) based complex was obtained (Form II).•Spectroscopic and X-ray studies were carried out.•In the six-coordinate Form II the nitrate is bidentate.•The complex interact with DNA moderately. Here, we present a new polymorph of the [Cu(5mebipy)(NO3)]NO3 complex (1, Form II), where 5mebipy means 5,5′-dimethyl-2,2′-bipyridine. The copper(II) complex 1 was characterized by spectroscopic techniques and single-crystal X-ray diffraction. The Form II presents a six-coordinated structure, meanwhile the Form I, previously reported, is five-coordinated with the nitrate ligand as monodentate. The molecular structures of both crystalline forms were compared based on intramolecular aspects using Kleywegt's analysis and the intermolecular contacts evaluated by Hirshfeld surface studies. Moreover, the interaction of the complex [Cu(5mebipy)(NO3)]+ with CT-DNA was carried out using viscosity and spectrophotometric titrations, exhibiting a binding constant of 2.57 × 104 M − 1. This study contributes to explore the intra and intermolecular details of the new polymorph of the complex [Cu(5mebipy)(NO3)]NO3 and its capability to interacts with CT-DNA. [Display omitted]