Complex formation, thermal behavior and stability competition between Cu(II) ion and Cu0 nanoparticles with some new azo dyes. Antioxidant and in vitro cytotoxic activity

Four triazole and thiadiazole-based azo chromophores namely [(E)-4-((1H-1,2,4-triazol-3-yl)diazenyl)benzene-1,3-diol.(HL1), (E)-4-((5-(methylthio)-1H-1,2,4-triazol-3-yl)diazenyl)benzene-1,3-diol.(HL2), (E)-4-((1,3,4-thiadiazol-2-yl)diazenyl)benzene-1,3-diol.(HL3) and (E)-4-((5-mercapto-1,3,4-thiadiazol-2-yl)diazenyl)benzene-1,3-diol.(HL4)] were synthesized and characterized by elemental analyses, IR, UV–Vis as well as mass spectroscopy. Cu(II) complexes of the investigated azo dyes have been synthesized and characterized by elemental analyses, IR, electronic and ESR spectra, magnetic susceptibility and thermogravimetric analyses. The bond lengths and bond angles have been calculated to confirm the geometry of the ligands and their Cu(II) complexes. The mode of interaction of the azodyes to copper nanoparticles was described as coordination mode of charged dye molecules on the colloidal Cu0 surface through anchoring OH− group. The apparent association constants of the colloidal copper nanoparticles azodye complexes in solution were evaluated using the spectral method and compared with the formation constant of the Cu(II) azo complexes. The antitumor and antioxidant activities of the synthesized azo dyes and their Cu(II) azo complexes have been evaluated.

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► Cu(II) complexes of four triazole and thiadiazole-based azo chromophore were synthesized and characterized.
► The mode of interaction between the synthesized azo ligands and copper nanoparticles was studied.
► The antitumor and antioxidant activities of the synthesized azo ligands and their Cu(II) azo complexes have been evaluated.