Synthesis of Bimetallic Palladacycles Via C-H Bond Activation: Crystal Structure, DNA Binding and in Vitro Cytotoxicity Study

Herein, we report the synthesis, characterization and in vitro anticancer activity of two mu-Cl and mu-O bridged dimeric cyclometalated palladium(II) complexes having general formula [Pd2(L1)Cl2] (1) and [Pd2(L2)Cl2] (2). The complexes are synthesized via palladium assisted aromatic C-H bond activation of coordinating ligands (HL1/HL2) and thoroughly characterized by spectroscopic techniques. X-ray crystal structure analysis has confirmed the square planar geometry of the complexes. DFT and TDDFT results have interpreted the electronic structure and solution spectra of the complexes. Cytotoxicity of the complexes was studied by in vitro model with human gastric cancer cell lines (AGS). Cytotoxicity investigation reveals that the complexes have promising anticancer activity, with IC50 values of 13.03 mu M and 17.86 mu M for 1 and 2, respectively. UV-vis and fluorescence techniques are used to examine how the complexes interact with CT DNA. Fluorescence-based competitive binding analysis with ethidium bromide (EB) indicates that the complexes effectively displace EB from the EBDNA complex.