Synthesis, Characterization, Crystallographic Structure, Theoretical Studies, and in Vitro Cytotoxicity Assessment of Two Gd(III), Ce(IV) Complexes of Pyridine-2,6-Dicarboxylic Acid

This paper reports the synthesis of two complexes through one-pot reactions of pyridine-2,6-dicarboxylic acid (pydcH2), phenanthroline, and 2-aminopyridine, with Gd(NO3)3.6H2O and Ce (NO3)3.6H2O metal salts. The new coordination complexes C1 and C2 have been identified by spectroscopic methods. The complexes were characterized by X-ray crystallography. The nature of metal-ligand interactions was studied theoretically using NBO and EDA-NOCV analyses. The results showed that the contribution of electrostatic interactions in both complexes is considerably larger than orbital. However, the contribution of orbital interactions in [CeL3]2–, is more than that in [GdL3]3– (28.8% vs. 21.8%). In following, the cytotoxic effect of synthetic complexes was investigated in vitro using oxaliplatin as a standard against three cancer cell lines including human breast cancer (MCF7), human colon adenocarcinoma (HT29), and human lymphocyte (HL60). The most significant inhibition activity was observed by both C1 (IC50=80.7 μM, Viability inhibition=83.41%) and C2 (IC50=98.3 μM, Viability inhibition=77.19%) toward the MCF7 cell line.