Lanthanide (III) complexes (Ln = Er and Yb) based on polypyridyl ligand: Synthesis, crystal structure, DNA-binding activity and interaction with human serum protein in vitro

•Two Ln(Er and Yb) polypyridyl complexes were synthesized and characterized.•Various spectroscopic techniques have suggested the structure of the two complexes.•UV-vis and fluorescence spectra suggest moderate intercalative binding modes between the complexes and DNA.•Two Complexes displayed efficient oxidative cleavage of supercoiled DNA.•Both Complexes bind to HSA with a medium affinity through a static mode. Two lanthanide complexes [Er(acac)2(o-NPIP)2](CH3CH2OH)2 (1) and [Yb(acac)2(o-NPIP)2](NO3)2 (2) (acac = acetylacetonate, o-NPIP = 2-(2-nitrophenyl)imidazo[4,5-f]1,10-phenanthroline) have been synthesized and characterized by X-ray single-crystal analysis, IR and electronic spectra. The two complexes are isostructural, which crystallizes in the triclinic crystal system. By binding two types of o-NPIP ligands and acetylacetonate molecules, Ln(III) (Ln = Er and Yb) ion shows a distorted square antiprism geometry. That DNA binding and human serum albumin (HSA) interacting with Ln (III) complexes have been investigated by UV–Vis spectra, fluorescent spectra and agarose gel electrophoresis. Both complexes showed moderate intercalative binding mode and oxidative cleavage ability with DNA. In addition, complexes 1 and 2 quenched the intrinsic fluorescence of HSA effectively by static mechanism. The binding molecular number was about one between two complexes and HSA. Moreover, the thermodynamic parameters ΔG, ΔH and ΔS revealed that two complexes combined with HSA through hydrophobic interactions. We have synthesized and characterized two Ln(Er and Yb) polypyridyl complexes, which showed effectively binding activity to DNA. Both complexes displayed efficiently oxidative cleavage to supercoiled DNA in the presence of H2O2. The two complexes effectively quenched the intrinsic fluorescence of HSA via static mechanism. [Display omitted]