Salicylidene‐based homoleptic metal(II) complexes: Theoretical, in silico molecular modeling and in vitro cytotoxicity studies

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A series of 12 salicylidene‐based homoleptic nickel(II), copper(II) and zinc(II) complexes with the general formula [M(L1–4)2] (1–12) containing the tridentate ligands 2‐(((2‐(([1,1′‐biphenyl]‐3‐ylmethylene)amino)phenyl)imino)methyl)phenol (HL1), 2‐(((2‐(([1,1′‐biphenyl]‐3‐ylmethylene)amino)phenyl)imino)methyl)‐4‐methoxyphenol (HL2), 2‐(((2‐(([1,1′‐biphenyl]‐3‐ylmethylene)amino)phenyl)imino)methyl)‐4‐ethoxyphenol (HL3) and 2‐(((2‐(([1,1′‐biphenyl]‐3‐ylmethylene)amino)phenyl)imino)methyl)‐4‐nitrophenol (HL4) have been synthesized and characterized by spectroscopic analysis. The tridentate nature of the ligands form an octahedral geometry around the central metal ion through the phenolic oxygen via deprotonation and two azomethine nitrogen atoms. Further, the charge transfer transitions taking place in the complexes have been explained using HOMO‐LUMO analysis. The in vitro cytotoxicity activity screened by WST assay against human metastatic (MDA‐MB‐231), hepatoma (HepG2) and colorectal adenocarcinoma (CaCo2) cancerous, and normal mouse fibroblast (NIH3T3) cell lines showed higher activity for the complexes 2, 6 and 10 with respect to the standard drug 5‐fluorouracil. The AO/EB, PI, Rh123 and DCFH‐DA staining results indicated that the complexes induced anticancer activity through apoptosis. Furthermore, the complexes interact with FGFR and P13Kγ kinase receptors through the hydrophobic, hydrogen bonding, π–π, σ–π, van der Waals and electrostatic interaction.