Hydrazone complexes of Cu(II), Co(II), Zn(II), Ni(II) and Pt(II) with N-isonicotinoyl-N′-(3-metoxy-2 hydroxybenzaldehyde)-hydrazone (HL) were synthesized and characterized by different physico-chemical techniques including elemental and thermal analysis, magnetic susceptibility measurements, molar electric conductivity, as well as IR (infrared), ¹H-NMR and ¹³C-NMR (hydrogen and carbon nuclear magnetic resonance, UV-Vis (ultraviolet-visible), FAB (fast atom bombardment), EPR (electron paramagnetic resonance), and mass spectroscopies. The crystal structure of ligand was determined by single crystal X-ray diffraction studies. Spectral data showed that hydrazone behaves as an ONO tridentate ligand through the azomethine nitrogen, phenolate and keto oxygen atoms. For the copper(II) complexes, metal–ligand bonding parameters were evaluated from the EPR spectra. These parameters indicate the presence of in-plane π bonding. In addition, the f values of complexes 1–4 indicate small distortion from planarity. The effect of these complexes on proliferation of human breast cancer (MCF-7 and SKBR-3), human melanoma (A375), lung adenocarcinoma cells (NCI-H1573) and their antibacterial activity against Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus and Candida albicans strains were studied and compared with those of free ligand. The ligand and complexes 1–3 showed significant antimicrobial activity against the Gram-positive bacteria Staphylococcus aureus and Candida albicans in comparison to the control drugs. The complexes 2–4 could be potential antitumor agents, leading to a significant improvement of the cytotoxic activity when compared with HL.

Extensive research has been conducted on ZrO₂ nanostructures due to their favorable biocompatibility, low toxicity, and promising prospects in various biomedical applications. They can be used as drug carriers, facilitating the administration of therapeutic substances into the body while enhancing their effectiveness and safety. This is achieved by regulating the timing, location, and rate at which drugs are released within the body. Several factors can influence the effectiveness of drug loading onto ZrO₂ nanostructures, such as the physicochemical characteristics of the drugs, the surface properties of the ZrO₂ nanostructures, and the specific methods used for drug loading. A wide range of drugs may be loaded onto ZrO₂ nanostructures including anti-cancer drugs, antibiotics, anti-inflammatory drugs, antifungal drugs, anti-osteoporotic drugs, etc. The release kinetics of drugs can be influenced by different factors, such as the size and shape of ZrO₂ nanostructures, the pH and temperature of the release medium, and the characteristics and molecular weight of the specific drug being released. While ZrO₂ nanostructures have demonstrated significant potential as drug delivery systems, further research on these structures is essential to optimize drug loading and release strategies.

A bidentate NO donor Schiff base, 2‐(((2‐chloro‐5‐ (trifluoromethyl)phenyl)imino)methyl) phenol (HL¹) and its complexes [Co(L¹)₂(H₂O)₂] (1), [Cu(L¹)₂] (2), [Mn(L¹)₂(H₂O)₂] (3), [Ni(L¹)₂(H₂O)₂] (4), [Pd₂(L¹)₂(OAc)₂·1.16H₂O] (5), [Pt(L¹)₂] (6) were synthesized and characterized by different physico‐chemical techniques including elemental and thermal analysis, magnetic susceptibility measurements, molar electric conductivity, IR, ¹H‐NMR, ¹³C‐NMR, UV–Vis, mass spectroscopies and X‐ray powder diffraction (XRD). The molecular structures of ligand HL¹ and two complexes (2 and 5) were confirmed by X‐ray crystallography analysis on the monocrystal. In this complexes, the metal ions are in distorted square‐planar environments. The copper (II) complex is mononuclear and crystallized in a monoclinic space group P21/c, whereas palladium (II) complex is dinuclear and crystallized in the trigonal crystal system R‐3. The toxicity of the ligand and complexes was evaluated on both plant and animal cells, using the plant species Triticum aestivum L. and the crustacean Artemia franciscana Kellogg. At concentrations up to 100 μM the compounds presented very little toxicity on Artemia franciscana Kellogg. Moreover, the palladium (II) complex was devoid of any toxicity on the plant cells.