Synthesis, Structural Elucidation, and Anticancer Efficacy Evaluation of a Novel Nd(III)-Schiff Base Complex:...

This study reports the synthesis, characterization, and biological evaluation of a novel Nd(III) complex with a newly designed Schiff base H₂L derived from 2-hydroxy-1-naphthaldehyde and l-histidine. The coordination, structure, and formula were determined using elemental analysis, molar conductivity, FT-IR and ¹HNMR spectroscopies, TGA, and XRD. The ligand acts as a tetradentate donor and a distorted octahedral geometry was proposed for the Nd(III) complex, coordinating via azomethine nitrogen and phenolic oxygen atoms. The cytotoxic activity of the ligand and its Nd(III) complex was evaluated against MCF-7 (breast), PC-3 (prostate), and A-549 (lung) human cancer cell lines using the MTT assay after 48 h. The inhibition rates of the complex were 97.19%, 95.73%, and 92.11% against A-549, PC-3, and MCF-7, respectively. Quantum chemical calculations revealed that the ligand exhibited two isoenergetic isomers stabilized by intramolecular hydrogen bonds. For [Nd^III(HL)(NO₃)₂], two isomers (A and B) were proposed, differing in the deprotonation site; Isomer B was more stable than A (ΔG = -37.6 kJ•mol^-1) at 298.15 K and 1.00 atm. The experimental results reveal that the cytotoxic activity of the ligand is improved upon coordination with Nd(III) and the complex could be a promising candidate for development a new lanthanide-based anticancer agent.