Synthesis, characterization, fluorescence and DNA-binding studies of europium(III) pirates complexes with amide-based 2,3-dihydroxynaphthalene derivatives

Two ligands 2,2′-[2,3-naphthylenebis(oxy)]-bis(N-benzyl(acetamide))(L1) and 2,2′-[2,3-naphthylenebis (oxy)]-bis(N,N-diphenyl (acetamide))(L2) and their europium(III) picrate complexes were synthesized. The complexes were characterized by elemental analysis, infrared (IR), thermogravimetry and differential thermal analysis (TG-DTA) and molar conductivity. Fluorescent experiments showed that the resonance level of the Eu(III) matched better to the triplet state energy level of the ligand L2 than that of the ligand L1 and the fluorescence intensities of the complexes were reduced with the raising coordination ability of solvent. In addition, the interactions between the complexes and DNA were studied by means of spectrometry and cyclic voltammetry. The results suggested that the complexes could bind to DNA through intercalation and the complex 1 binded to DNA more strongly than the complex 2.