In this paper, a Schiff base ligand 1-(2-thiophenylimino)-4-(N-dimethyl)benzene (SL1) bearing azomethine (>C=N-) and thiol (-SH) moieties capable of coordinating to metals and forming colored metal complexes was synthesized and examined as a colorimetric chemosensor. The sensing ability toward the metal ions of Cu2+, Cr3+, Fe2+ Ni2+, Co2+, Mg2+, Zn2+, Fe2+, Fe3+, NH4VO3 (V5+), Mn2+, Hg2+, Pb2+, and Al3+ was investigated in a mixture of H2O and dimethylformamide (DMF) solvent using the UV–Visible spectra monitoring method. The synthesized Schiff base ligand showed colorimetric properties with Cr3+, Fe2+, Fe3+, and Hg2+ ions, resulting in a different color change for each metal that could be identified easily with the naked eye. The UV–Vis spectra indicated a significant red shift (~69–288 nm) from the origin after the addition of the ligand to these metal ions, which may be due to ligand-to-metal charge-transfer (LMCT). On applying Job’s plot, it was indicated that the ligand binds to the metal ions in a 2:1 ligand-to-metal molar ratio. SL1 behaves as a bidentate ligand and binds through the N atom of the imine group and the S atom of the thiol group. The results indicate that the SL1 ligand is an appropriate coordination entity and can be developed for use as a chemosensor for the detection of Cr3+, Fe2+, Fe3+, and Hg2+ ions.

Vanadium complexes containing Schiff base ligands are of great importance and have numerous applications. A series of Schiff base ligands derived from 4-amino-5-mercapto-3phenyl-1,2,4-triazole and different aldehydes were synthesized and combined with ammonium metavanadate in 2:1 and 1:1 molar ration to yield oxo-and dioxo-vanadium(V) complexes NH4[VO(La-f)2] and NH4[VO2(Lg-h)2], respectively. The structure of the synthesized compounds was confirmed by elemental analysis, UV, IR, NMR, MS and TGA. Complexes with bidentate and tridentate ligands were expected to possess a distorted square-pyramidal structure. The ligands and their complexes have been examined for antimicrobial activity against six types of bacteria and one kind of fungus that widely distributed in Albaha region, Kingdom of Saudi Arabia. The results indicate that some of the complexes were active against C. albicans fungus when used as powder, and no sound activity were shown against any type of tested bacteria.

The synthesis of mixed-ligand complexes is considered an important strategy for developing new metal complexes of enhanced biological activity. This paper presents the synthesis, characterization, in vitro antimicrobial assessment, and theoretical molecular docking evaluation for synthesized oxidovanadium (V) complexes. The proposed structures of the synthesized compounds were proved using elemental and different spectroscopic analysis. The antimicrobial tests showed moderate activity of the compounds against the Gram-positive bacterial strains and the fungal yeast, whereas no activity was observed against the Gram-negative bacterial strains. The performance of density functional theory (DFT) was conducted to study the interaction mode of the targeted compounds with the biological system. Calculating the quantitative structure-activity relationship (QSPR) was performed depending on optimization geometries, frontier molecular orbitals (FMOs), and chemical reactivities for synthesized compounds. The molecular electrostatic potentials (MEPs) that were plotted link the interaction manner of synthesized compounds with the receptor. The molecular docking evaluation revealed that the examined compounds may possess potential antibacterial activity.

The purpose of this paper was to synthesis new mixed-ligand Cu(II) and Co(II) metal complexes utilizing bidentate and tridentate donor hydrazones derivatives as primary ligands and o-vanillin as co-ligand. The obtained compounds were characterized by elemental analysis, Infrared, UV-Vis., 1H-NMR, Mass spectra, molar conductance, thermal analysis and atomic absorption spectroscopy (ASS). Spectroscopic analysis results indicated that the hydrazone ligand (L1) behave as tridentate (ONO) and forms metal complexes having distorted square planar geometry. While the ligands (L2, L3 AND L4) behave as bidentate (NO) and forms metal complexes having octahedral geometry around the central metal atoms. The antimicrobial potentials were assessed for the ligand (L2) and its metal complexes only and were screened against six types of bacterial strains and one fungal strain. The antimicrobial activities results of the tested compounds showed enhanced activity of the complexes over their parent ligands.

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The antimicrobial resistance is a global human threat which has led to the withdrawal of antibiotics from the market. Therefore, it is a need to develop new and effective antimicrobial agents to overcome this problem. In this paper, new Dioxovanadium(V) complexes (1–8) with ligands viz. (2-(5-phenyl-1,3,4-oxadiazole-2-yl)phenol; L1) and 2,5-bis(2-hydroxyphenyl)-1,3,4-oxadiazole (L2) were synthesized and assessed for antimicrobial-activity. Both a bidentate and tetradentate oxadiazole ligands coordinate with vanadium ions through the nitrogen and oxygen atoms giving octahedral geometries. Thermal analysis and IR data confirmed the presence of hydrated water in the metal-complexes. The investigated compounds were assessed for antimicrobial viz four strains of bacterial and one a fungal strain. The antibacterial data showed that, the complexes (1–8) are lower potency against bacterial strain than the free ligands except (5) and (7) complexes. These complexness showed the highest antibacterial potency via the Staphylococcus aureus. All investigated compounds were inactive against C. albicans except complexes 2 and 5 which showed high activity. The performance of DFT was conducted to examine an interaction mode of the target compounds with biological system. The QSPR was calculated as: optimization geometries, (FMOs), and chemical-reactivities for the synthesized compounds. The (MEPs) were figured to predict the interaction behavior of the ligand and its complexes against the receptor. The molecular docking was performed against DNA gyrase to study the interaction mode with biological system.

New Vanadium(V) complexes with new ligand 2-(4-((2-(carboxy) phenoxy) methyl)-1H-1,2,3triazol-1-yl)benzoic acid (L 1 ) has been synthesized and characterized by different analytical techniques such as elemental analyzer, 1 H NMR, UV-Vis, IR, Mass spectrometry and thermal gravimetric analysis (TGA). The analytical data showed the stoichiometry of the Vanadium(V) to ligand was 1:1, and also indicated that the ligand (L 1 ) coordinate to the vanadium ions through oxygen and nitrogen atoms giving octahedral geometry. The ligands and their complexes have been examined for antimicrobial activity against four types of bacterial strains and one fungal strain. All the tested ligands and their complexes showed moderate to significant activity against Staphylococcus aureus, where the complex N(Pr) 4 [VO(L 1 )] (4) showed highest activity comparable to the standard drug, Amoxicillin. The other tested bacterial strains were resistant against the ligands and their complexes. The result of antifungal activity against the pathogenic fungi C. albicans indicated that the tested strain was resistant towards the ligand and its vanadium (V) complexes.

The ligand 3-(-(2-hydroxyphenylimino) methyl)-4H-chromen-4-one (SL) has been synthesized and examined as a chemosensor for some metal ions in aqueous solutions based on colorimetric analysis. Color changes were monitored using UV–visible spectroscopy. Binding stoichiometry and limit of detection (LOD) were estimated using titration experimentation based on UV–visible absorbance and Job’s plot. The synthesized ligand was tested for selectivity in the presence of several cations and was examined for possible utility as a chemosensor in real water samples. The results indicated sensing ability and selectivity for Cu2+, Fe3+, and V5+. Stable complexes were formed between SL and Cu2+, Fe3+, and V5+, and the ligand-to-metal binding stoichiometry was found 2 : 1 in the SL-Cu2+ and SL-Fe3+ complexes, and 1 : 1 in the SL-V5+ complex. The results of LOD and bending constant were (7.03 μM, 1.37 × 104 M−1), (5.16 μM, 2.01 × 104 M−1), and (5.94 μM, 1.82 × 104 M−1) for Cu2+, Fe3+, and V5+, respectively.