Abstract: In this study, a hydrazone Schiff base ligand and its Fe(III) complex were synthesized. The hydrazone ligand was derived from hydrazone and benzaldehyde, and its antimicrobial properties were systematically evaluated. The synthesis of the Schiff base ligand was done by the condensation of 2-(2-aminothiazol-4-yl)acetohydrazide with 2-nitrobenzaldehyde, followed by complexation with FeCl₃ in a 1:2 molar ratio. Characterization was achieved using spectroscopic and analytical techniques, including ¹H-NMR, FTIR, UV-Vis, and XRD, which confirmed the successful formation of the ligand and its coordination to Fe(III). The ¹H-NMR spectrum confirmed the formation of the imine linkage (δ 8.09 ppm), while FTIR and UV-Vis data supported the presence of C=N bonding and metal-to-ligand charge transfer, respectively. XRD showed an amorphous structure consistent with flexible hydrazone linkages. Antimicrobial activity was screened against Escherichia coli, Salmonella typhi, Staphylococcus aureus, Streptococcus pyogenes, and Candida albicans using the agar well diffusion method. The Fe(III) complex demonstrated superior inhibitory activity compared to the free ligand, with the most significant enhancements observed against Staphylococcus aureus (20 mm vs. 16 mm) and Salmonella typhi (20 mm vs. 12 mm). These results suggest that metal coordination substantially enhances the antimicrobial efficacy of Schiff base ligands. The synthesized Fe(III) complex has potential as a lead candidate for the development of novel antimicrobial agents, given the rising issue of multidrug resistance.

With the aim to explore potential drugs against tuberculosis and microbial infections, eight diorganotin(IV) complexes were synthesized from 4-nitro-3-methylbenzhydrazide. Various techniques, including NMR, FT-IR, and mass spectrometry, were used to fully characterize the compounds (1–10). Further, DFT studies were conducted with the help of Gaussian 09 software for compounds to get an insight for their biological potential by employing quantum mechanical principles. The evaluation of anti-tuberculosis results revealed that compounds 6 and 10 exhibited the highest potential to inhibit TB infections, having minimum inhibition concentration (MIC) values of 0.0194 ± 0.0004 and 0.0195 ± 0.0005 µmol/mL, respectively. Results of anti-microbial analysis revealed that compound 6 showed the highest efficacy against tested microbes with MIC values around 0.0194 ± 0.0048 µmol/mL.

It is aimed to perform an evaluation of a hydrazone derivative of the vic-dioxime ligand by examining its structural properties, bioactivity via molecular docking and absorption, distribution, metabolism, excretion (ADME) analysis, and stability using molecular dynamics (MD). With this respect, the innovative design, synthesis, and advanced in silico analysis of a novel vic-dioxime hydrazone ligand, (1Z,2E)-2-(hydroxyimino)-N'-[(1Z)-3,4,5-trimethoxyphenyl)methylene]ethanehydroximohydrazide (LH2) was explored. The compound was characterized through a series of spectroscopic techniques, including ¹H NMR, ¹³C NMR, FT-IR, and UV-Vis spectroscopy. In silico studies were performed to evaluate the ligand's binding affinities to major proteins of RAS/RAF/MEK/ERK signaling pathway through molecular docking. ADME profiling was conducted to assess the ligand's pharmacokinetic properties. Additionally, MD analysis was performed to evaluate the binding stability of the target-compound complex through RMSD, RMSF, RG, hydrogen bonding and MMPBSA free energy calculations. As a result of molecular docking analysis, the compound was found to have the highest binding energy value to RAS among the other target proteins RAF and ERK. In addition, it was obtained that LH2 complies with the conditions required to satisfy Lipinski's rule of five. Moreover, ERK-ligand complex exhibited the highest stability among the tested targets according to the MD simulation results. According to the results of the investigation, in silico anti-cancer activity was revealed based on molecular docking analysis and it was determined that novel vic-dioxime hydrazone ligand could act as a targeted therapeutic RAS/RAF/MEK/ERK pathway inhibitor in colorectal cancer.

Ultrasound-assisted synthesis of Nanosized like rods Cr(III), Mn(II), and Ru(III) complexes with a novel Hydrazone ligand: Structural, DFT, biomedical, and molecular docking investigations

Role of nucleophilicity versus basicity of co-ligand on the selective formation of VO3+/VO2+ motif from a VO2+ precursor in presence of a tridentate hydrazone ligand

Given the outstanding magnetic characteristics of lanthanide ions, the development of mononuclear or multinuclear lanthanide complexes becomes imperative. Previous research showed that a series of mononuclear Dy(III) complexes of rhodamine benzoyl hydrazone Schiff base ligands exhibit remarkable single-molecule magnetic properties and fluorescence. In this study, we used analogous ligands to synthesize lanthanide complexes [Dy(HL1-o)(NO3)2(CH3OH)2]NO3·CH3OH (complex 1·MeOH) and tetranuclear complexes [Ln4(L1-c)2(L2)2(μ3-OH)2(NO3)2(CH3OH)4](NO3)2·2CH3CN·5CH3OH·2H2O (Ln = Dy, complex 2; Ln = Gd, complex 3). Magnetic susceptibility measurements show that 1·2H2O is a single-molecule magnet, 2 shows slow magnetic relaxation and 3 is a magnetic cooling material with the magnetic entropy change of 9.81 J kg−1 K−1 at 2 K and 5 T. The theoretical calculations on 1·MeOH indicate that it shows good magnetic anisotropy with the calculated energy barrier of 194.6 cm−1.

ABSTRACTA series of Ni(II), Co(II), and Cu(II) complexes with N′1,N′2‐bis((E)‐1‐(pyridin‐2‐yl)ethylidene)oxalohydrazide (H2OHS) were synthesized and characterized using FT‐IR, UV–Vis, NMR, ESR, and thermal analyses. Density functional theory (DFT) calculations confirmed structural stability, electronic properties, HOMO–LUMO gaps, and charge‐transfer characteristics, supported by reduced density gradient (RDG) and noncovalent interaction (NCI) analyses. The complexes exhibited distinct geometries—octahedral for Ni(II), tetrahedral for Co(II), and square planar for Cu(II). Thermal degradation studies using Coats–Redfern and Horowitz–Metzger methods revealed high thermal stability. Biological evaluations demonstrated strong antimicrobial activity against Candida albicans, Staphylococcus aureus, Escherichia coli, significant antioxidant potential (DPPH and ABTS), and potent cytotoxic effects against HepG2, MCF‐7, HCT116, and A549 cancer cell lines. Molecular docking studies confirmed strong ligand–receptor interactions, correlating with biological efficacy. These findings highlight the complexes' promising potential as multifunctional therapeutic agents in antimicrobial, antioxidant, and anticancer applications.

Synthesis and characterization of Fe(II)- and Cr(II)-complexes with isatin-aryl hydrazone ligand as bio-reactive reagents and effective catalysts for styrene epoxidation.

Efficient artificial light‐harvesting systems (ALH) involving energy transfer via FRET in an aqueous environment has been reported. Hydrazone ligands L1−L3 and ‐BF2 complexes (BODIHYs; B1−B3) derived from these have been synthesized and meticulously characterized by various techniques like1H, 13C, 11B, 19F NMR, ESI–MS, UV–vis, fluorescence spectroscopy, and structures of B1 and B2 unequivocally determined by X−ray single crystal analyses. Applicability of the B1−B3 have been examined as a LHS platform and categorically shown that these in combination with rhodamine B (RhB) display efficient light harvesting activity under aqueous conditions via aggregation−induced emission (AIE). Calculated energy transfer efficiency and antenna effect for the BODIHYs are significantly high (B1 = 22%, 5.04; B2 = 18%, 4.07) at a donor/acceptor ratio of 23:1. Furthermore, hypsochromic shift shown by B1 and B2 after grinding completely reverses upon exposure to dichloromethane vapors. Powder X−ray diffraction (PXRD) analyses before and after grinding revealed that the external forces modify crystal packing by disrupting weak intra− and intermolecular interactions within the molecules.

An efficient strategy for the multicomponent synthesis of pyrimidine analogues has been demonstrated via acceptorless dehydrogenative annulation (ADA) of alcohols utilizing new Ni(II)-NNO pincer complexes as catalysts. The newly formed Ni(II) complexes (C1-C4) featuring N^N^O chelating hydrazone ligands are well established through analytical and spectral methods (FT-IR and NMR). Single-crystal X-ray diffraction analysis precisely reveals the NNO coordination fashion and square planar geometry around the metal center. The catalytic performance of the complexes is validated through the smooth and efficient synthesis of pyrimidine derivatives from the dehydrogenative coupling of primary alcohols, benzamidines/guanidines/acetamidines, and 1-phenylethanol and delivers the desired products up to 92% with a catalyst loading of 2 mol %. Time-dependent control experiments evidence the formation of probable intermediates such as aldehyde, ketone, and chalcone. The catalytic system displaces a variety of 2,4,6-trisubstituted pyrimidines (27 examples) and H2O and H2 are the sole byproducts. Additionally, a successful gram-scale synthesis highlights the industrial applicability of this catalytic protocol.

Their demonstrable bioactive characteristics, coupled with their wide structural diversity and coordination versatility, render Schiff bases and their coordination complexes biologically active compounds demonstrating outstanding properties. This research describes the synthesis and characterization of new Cu(II) and Ni(II) complexes with an NNO-donor hydrazone ligand (HL). The crystal structure of the HL ligand was determined through single-crystal X-ray diffraction studies. The in vitro antibacterial activities of the HL ligand and its metal(II) complexes against Gram-positive and Gram-negative bacteria demonstrated that the metal(II) complexes displayed greater antimicrobial activities compared to the free Schiff base ligand. Furthermore, the interaction of the ligand and the complexes with calf thymus DNA (CT-DNA) was explored through electronic absorption and viscosity measurements, suggesting intercalation as the most likely mode of binding. The compounds promoted oxidative DNA cleavage, as demonstrated by the strand breaks of the pmChery plasmid under oxidative stress conditions. Finally, fluorescence spectroscopy also revealed the strong binding affinity of these compounds for bovine serum albumin (BSA).

Synthesis, Characterisation, Biological activity of Zn, Co, Ni, Mn and Cu complexes with hydrazone ligand

Synthesis, characterization, antioxidant, and molecular docking studies on COVID-19 and breast cancer of novel Cr3+, Mn2+, and VO2+ chelates obtained from novel Schiff base hydrazone ligand

Abstract This study highlights the electrochemical drug (ECD) sensor with a glassy carbon electrode modified with ruthenium(II) complex (RBNH), which showed a stronger response to the detection of tetracycline (TC) antibiotic residue in real samples like chicken eggs and cow milk compared to other substrate materials. Glassy carbon electrodes are covalently functionalized with ruthenium(II) complex containing the redox active 2, 2 bipyridine, and a hydrazone ligand (BNH) via., drop casting method. This results in the electrocatalytic behavior of the modified electrode (GCE/RBNH) on the oxidation of TC. Further, the modified electrode′s sustainability was tested with various antibiotics, including different concentrations of tetracycline, and scan rates by different techniques like cyclic voltammetry (CV), linear sweep voltammetry (LSV). Then a GCE/RBNH was used to create a linear calibration curve for TC concentrations ranging from 10 to 100 μmol L−1 (R2=0.99), with a limit of detection and quantification 0.0675 μmol L−1 and 0.224 μmol L−1. The current approach, which possesses an effortless electrode modification step and offers the lowest detection limit and a comparatively wider linear dynamic range, performed better for determining TC in chicken eggs and milk samples than recently reported voltammetric methods.

ABSTRACTA novel quinolinyl hydrazone ligand (NaphHQino) has been synthesized by condensation of 2‐hydrazinyl‐4,7‐dimethylquinoline with 2‐hydroxy‐1‐naphthaldehyde. Reactions of NaphHQino with copper(II), nickel(II), and cobalt(II)‐chlorides yielded a series of novel complexes. Structures of the NaphHQino ligand, Cu‐NaphHQino, Ni‐NaphHQino, and Co‐NaphHQino complexes have been inspected with the help of elemental and thermal analyses, magnetic susceptibility and molar conductivity measurements, infrared, electron spin resonance (ESR), proton nuclear magnetic resonance (1H NMR), mass, and electronic spectra. The studied NaphHQino ligand acts either as a neutral NN‐donor or as a dibasic tridentate NNO‐donor, forming square‐planar complexes. Molar conductivity measurements demonstrate a neutral character of the NaphHQino complexes. The ESR spectrum of the Cu‐NaphHQino complex confirmed the proposed square‐planar geometry with values of α2 and β2, demonstrating that the in‐plane π‐bonding character is less prominent than the covalent in‐plane σ‐bonding character. Implementing density functional theory at the B3LYP/6‐311G(d,p) and LanL2dz levels, the molecular fundamental properties of NaphHQino and NaphHQino‐complexes were assessed. NaphHQino ligand exhibited antineoplastic activity towards Ehrlich ascites carcinoma, and metal‐NaphHQino complexes showed higher activity than NaphHQino. Molecular docking simulations were carried out, which supported the obtained results for antineoplastic activity.

Organotin(IV) complexes anchored on the magnetic UiO-66-NH2 metal–organic framework: Synthesis and evaluation of cytotoxicity

Abstract Novel hydrazone ligand 2‐(2‐(2‐hydroxy‐5‐methoxybenzylidene) hydrazinecarbonyl) pyridine 1‐oxide was synthesized and characterized by spectral analyses. The assessment of number of dissociable protons in ligand and evaluation of corresponding values of pKa and the stability constants for M(II)‐Ligand systems (M (II) = Cu, Co, Ni and Zn) in 30% DMF‐water medium were done by adopting pH‐metric method following Irving‐ Rossotti technique. To understand the chelation properties of hydrazone ligand, its contour maps of frontier molecular orbitals and their energies were computed using HyperChem 7.5 tools. The synthesized metal complexes of above hydrazone with Cu (II), Co (II), Ni (II) and Zn (II) were characterized with spectral and analytical techniques such as; FT‐IR, 1H‐NMR, LC‐MS, TGA, UV‐Vis, FE‐SEM‐EDX and ESR. The tridentate and dibasic nature of title ligand is ascertained from pH‐metric studies as well as through the analyses of analytical and spectral data of complexes. The CT‐DNA binding studies conducted adopting absorption and fluorescence titrations with metal complexes and ligand inferred their binding affinity through the mode of intercalation. The evaluated antioxidant and cytotoxicity properties revealed higher efficacy of copper complex. Furthermore, investigations employing molecular docking studies revealed non‐covalent bonding interactions of synthesized compounds with chosen protein target CDK2.

Vanillin Derived Hydrazone Ligands and Their Transition Metal Complexes: Synthesis, Characterization, Biological Activity and Molecular Docking Studies

ABSTRACTIn the search of antiplasmodium agents, the hydrazone ligands, that is, (2‐hydroxy‐5‐nitrobenzylidene)benzo[b]thiophene‐2‐carbohydrazone (H2L1)/(3,5‐dichloro‐2‐hydroxybenzylidene)benzo[b]thiophene‐2‐carbohydrazone (H2L2) and their Co(II), Ni(II), Cu(II), and Zn(II) metal complexes were synthesized. All the compounds were well characterized by wide range of spectral and physical techniques, that is, FT‐IR, 1H NMR, 13C NMR, ESR, mass spectrometry, UV‐Vis, XRD, SEM‐EDAX, molecular conductivity, and thermal studies (TG‐DTA). The coordination by O‐phenolic, O‐enolic, and N‐azomethine donor atoms and three aqua ligands to metal(II) ions was confirmed by various physicochemical techniques, affirming the octahedral geometry of the metal complexes. Biological evaluation of the synthesized compounds involved assessing by their antiplasmodium potency utilizing microassay and antimicrobial activities using serial dilution technique. The Cu(II) (5, 6) and Zn(II) (9, 10) metal complexes significantly inhibited the growth of parasitic ailments caused by Plasmodium falciparum 3D7 strain and also exhibited remarkable antimicrobial effectiveness against diseases caused by microbes comparable with the standard drugs (ciprofloxacin and fluconazole). Moreover, theoretical study including molecular docking was employed utilizing 3,5‐dihydroxy‐2‐naphthoic acid (PDB:1U5A) P. falciparum protein receptor to validate the antiplasmodium effectiveness of the most potent H2L1 hydrazone ligand (1) and their complexes (3–6). This analysis indicated that the docked compounds could serve as a promising drug candidate for malaria. whereas the ADMET profiling authenticated the drug‐like features of compounds 1 and 3–6. Thus, this research provides fresh perspectives for in vivo study of the compounds with minor developments.

In the past few decades, the concern over the excessive use of fossil fuels and consequent environmental damage has triggered the search for cleaner and renewable energy resources. This has led to the consideration of hydrogen as our future fuel. It can be produced from various sources, and if used as fuel, it generates only water as a byproduct. Electrocatalytic reduction of protons (2H+ + 2e- → H2) is one of the available methods for producing hydrogen gas at large scales. Currently, the most efficient electrocatalysts are Pt-based complexes. In order to make the entire process more cost-effective, it has become necessary to find electrocatalysts that are derived from earth-abundant metals such as Ni, Zn, Fe, etc. Herein, we have demonstrated the electrocatalytic hydrogen evolution reaction (HER) catalyzed by pyridyl aroyl hydrazone ligand (HL)-based metal complexes (M = Fe, Co, Ni, Cu, and Zn). Rate calculations using controlled potential electrolysis revealed the optimal overall catalytic performance of NiL2 among the investigated complexes. For NiL2, a maximum turnover frequency of 7040 s-1 with a 0.42 V overpotential was obtained when triethylamine hydrochloride was used as a proton source. Both experimental and density functional theory (DFT) calculations suggested a ligand-centered metal-assisted catalysis pathway for NiL2 in the presence of triethylammonium chloride.