Synthesis, characterization, cytotoxic activity and DNA-binding properties of the Ln(III) complexes with ethylenediiminobi(6-hydroxychromone-3-carbaldehyde) Schiff-base

A new ligand, ethylenediiminobi(6-hydroxychromone-3-carbaldehyde) Schiff-base (L), was prepared by condensation of 6-hydroxy-3-carbaldehyde chromone (CDC) with ethylenediamine. Its three rare earth complexes have been synthesized and characterized on the basis of elemental analyses, molar conductivities, mass spectra, 1H NMR, thermogravimetry/differential thermal analysis (TG-DTA), UV–vis spectra, fluorescence spectra and IR spectra. The general formula of the complexes is [LnL·(NO3)2]·NO3 [Ln = Sm (1), Eu (2), La (3)]. Complexes 1, 2 and 3, and ligand L were subjected to biological tests in vitro using HepG2 cancer cell lines. Ligand showed significant cytotoxic activity against HepG2cancer cell lines. Spectrometric titration, ethidium bromide displacement experiments and viscosity measurements indicate that Sm(III) and Eu(III) complexes strongly bind with calf thymus DNA, presumably via an intercalation mechanism. The intrinsic binding constants of complexes 1 and 2, and ligand with DNA were 9.28 × 106, 8.40 × 106 and 4.88 × 106 M−1 through fluorescence titration data, respectively.