Synthesis and structure of new dicopper(II) complexes bridged by N-(2-hydroxy-5-methylphenyl)-N′-[3-(dimethylamino)propyl]oxamide with in vitro anticancer activity: A comparative study of reactivities towards DNA/protein by molecular docking and experimen

• Two dicopper(II) complexes are characterized by X-ray analysis and other methods.
• The two complexes show higher cytotoxicity than cisplatin.
• The DNA/BSA-binding are studied theoretically and experimentally.
• The influence of hydrophobicity of both bridging and terminal ligands is discussed.

Two new dicopper(II) complexes bridged by N-(2-hydroxy-5-methylphenyl)-N′-[3-(dimethyl-amino)propyl]oxamide (H3hmpoxd), and end-capped with 4,4′-dimethyl-2,2′-bipyridine (Me2bpy) and 2,2′-bipyridine (bpy), were synthesized and structurally characterized, namely [Cu2(hmpoxd)(CH3OH)(Me2bpy)](ClO4) (1) and [Cu2(hmpoxd)(bpy)](ClO4)∙CH3OH (2). The single-crystal X-ray diffraction analysis reveals that the endo- and exo-copper (II) ions bridged by the cis-hmpoxd3− ligand are located in square-planar and square-pyramidal geometries, respectively, for 1, and square-planar environments in 2. The DNA/protein-binding natures are studied theoretically and experimentally, indicating that both the two complexes can interact with the DNA in the mode of intercalation, and effectively quench the intrinsic fluorescence of protein BSA via the favored binding sites Trp213 for 1 and Trp134 for 2. In vitro anticancer activities showed that the two complexes are active against the selected tumor cell lines, and the anticancer activities are consistent with their DNA/BSA-binding affinities following the order of 1 > 2. The synergistic hydrophobicity of the bridging and terminal ligands in these complexes on DNA/BSA-binding events and in vitro anticancer activities is preliminarily discussed.

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