Eu(III), Tb(III), and Gd(III) Complexes With Dual Ligand Architecture: Synthesis, Characterization, Photoluminescence, Cytotoxic, and Molecular Docking Studies.

By using the naphthalene group-containing β-diketone ligand and 5-nitro-1,10-phenanthroline, three novel heteroleptic eight-coordinate complexes of Eu(III), Tb(III), and Gd(III) have been synthesized. Methods such as elemental analysis, MALDI TOF-MS, UV-Vis, and FT-IR were used to determine the structural characterization of these compounds. The photoluminescent characteristics of the synthesized complexes of Eu(III), Tb(III), and Gd(III) were further investigated. The ligand (L1) and co-ligand 5-nitro-1,10-phenanthroline (L2) and its three lanthanide complexes [Eu(L1)3(L2)]·3H2O, [Tb(L1)3(L2)], and [Gd(L1)3(L2)] were tested in human breast (MCF-7), colon (DLD-1), and lung (A549) cancer cell lines for 72 h. Furthermore, these compounds were screened in a human embryonic kidney cell line (HEK-293T) for cytotoxicity. The results demonstrated that these compounds have antiproliferative activity in three cancer cell lines with low IC50 values. The probable mode of action for the cytotoxic effect was explored through molecular modeling. Previous studies reported epidermal growth factor receptor (EGFR)-inhibiting potential for compounds with similar scaffolds. The docking study demonstrated that the three chelates would have the potential to bind to the EGFR structure. The molecular dynamics (MD) simulation study consolidated this finding as the complex structures were found to be stable with some differences. MMPBSA (molecular mechanics with Poisson-Boltzmann and surface area solvation) energy calculation results also showed high binding affinities for the chelates.