<p>The new tetradentate derivative ligand, [4-((2-hydroxybenzylidene)amino)-N-(pyridin-2-yl)benzamide], of the N₂O₂ type, was prepared through a condensation reaction of equimolar amounts of ethyl 4-aminobenzoate and 2-aminopyrimidine, followed by the addition of salicylaldehyde. The ligand was characterised using spectroscopic and non-spectroscopic techniques, including FT-IR, UV–visible spectroscopy, ¹H and ¹³C NMR, melting point determination, elemental analysis, and DFT-optimized structural calculations. The ligand reacts with Ni(II), Co(II), Mn(II), and Pd(II) metal ions to form new nanometal complexes synthesized via ultrasonic sonication, with the general formula [M₂(LH)Cl₂(H₂O)₂]Cl₂. The size and morphology of the nanocomplexes were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The complexes were further characterised by FT-IR, UV–visible spectroscopy, conductivity measurements, magnetic moment determination, melting point analysis, and DFT optimization, in addition to an evaluation of their biological activity. The synthesised ligand and its metal complexes were tested for their antioxidant activity, anticancer activity against colon, and chest cancer cell lines, antibacterial activity against two Gram-positive and two Gram-negative bacteria, and antifungal activity. The prepared derivative and its nanometal complexes are shown in Scheme <InternalRef RefID="Sch1">1</InternalRef>.</p> Graphical Abstract <p></p>