Some novel rare earth metal ions complexes: Synthesis, characterization, luminescence and biocidal efficiency

New lanthanide complexes (1-3) of the general formulae [Ln(L)(NO₃)(H₂O)] have been synthesized by reaction of Ln(NO₃)₃ {Ln = La (1), Sm (2) and Yb (3)} with 2,2'-(((1E,1'E)-thiophene-2,5-diylbis(methaneylylidene))bis(azaneylylidene))diphenol (H₂L). Based on elemental analysis, spectroscopic studies (UV-Vis., FT-IR, ESI-MS, ¹H/¹³C NMR), molar conductance and thermogravimetric analysis, the Schiff base ligand was suggested to coordinate Ln(III) ions through the azomethine nitrogens, deprotonated hydroxyl groups, and thiophene sulphur atom. The interaction of the synthetic compounds with CT-DNA has been studied by the electronic spectroscopy, fluorometric competition studies with ethidium bromide and DNA viscosity measurements. Furthermore, due to the ligand and its Ln(III) complexes exhibit good DNA binding affinity, it is considered worthwhile to investigate their antioxidant activity. The data have shown that, the complexes are more effective inhibitors towards reactive oxygen species (ROS), such as superoxide anion and hydroxyl radical. The activity of test compounds in ascending order (1) > (2) > (3) > H₂L in terms of IC₅₀ value. The anticancer activities of the complexes have also been studied towards human colon carcinoma cancer (HCT-116) and human breast cancer (MCF-7) cell lines.