ONO Tridentate Schiff Base Research Articles

Urease inhibition studies of two Cu(II) complexes with an ONO tridentate Schiff base and two different secondary ligands: An experimental, DFT, molecular docking and molecular dynamics study

Two mononuclear Copper(II) complexes, identified as [Cu(C10H8NO4F)(C6H7N)] (C1) and [Cu(C10H8NO4F)(C12H8N2)]·H2O·CH3OH (C2), incorporating a tridentate Schiff-base ligand with an ONO coordination (C10H8NO4F = 5-fluoro-2-hydroxybenzylidene-L‑serine) and two unique auxiliary ligands (C6H7N = 4-methylpyridine and C12H8N2 = 1,10-phenanthroline) were developed and detailed structurally. Density functional theory (DFT) evaluations of these complexes employed Becke's three-parameter hybrid (B3LYP) approach within the Gaussian 16 computational package. The outcomes from computational analysis corresponded with experimental data. Additionally, the inhibition capabilities of complexes C1 and C2 were evaluated in vitro targeting jack bean urease. Simultaneously, molecular docking was utilized to determine potential binding interactions. Experimental results and docking analyses showed that C1 had considerable inhibitory strength (IC50 = 2.44 ± 0.15 μM) relative to the benchmark control, acetohydroxamic acid (IC50 = 27.73 ± 2.93 μM). Furthermore, a 100-ns molecular dynamics assessment was performed to examine the interaction stability of urease with C1 and C2, using the Desmond 2021 tool from Schrödinger. The correlation between structural configurations and inhibition efficacy was further explored through molecular docking, density functional theory analysis, and molecular dynamics evaluations.

New oxovanadium and dioxomolybdenum complexes as catalysts for sulfoxidation: experimental and theoretical investigations of E and Z isomers of ONO tridentate Schiff base ligand

A new ONO-tridentate Schiff base ligand (H2L) derived by the condensation of nicotinic hydrazide with 5-chlorosalicylaldehyde has been prepared and characterized by combustion analysis (CHN), FT-IR and multinuclear (1H and 13C) NMR spectroscopy. The crystalline nature and molecular structure of the ligand were confirmed by single-crystal X-ray diffraction analysis. Furthermore, the optimized structural parameters of the four possible configurations of the ligand including Z and E stereoisomers each containing two tautomeric forms (enol and keto) have also been investigated. The theoretical parameters were calculated by performing the DFT method using the B3LYP/Def2-TZVP level of theory. In addition to this, dioxomolybdenum(VI) (MoO2L) and oxovanadium(V) (VOL) complexes with the entitled Schiff base ligand have also been prepared and characterized by different techniques. Then, the catalytic efficiencies of synthesized VOL and MoO2L complexes were also explored for the oxidation of sulfides using 30% aqueous H2O2 as a source of oxygen. These homogeneous catalysts showed excellent catalytic activities in the oxidation of both aromatic and aliphatic sulfides.

Novel dioxomolybdenum complexes containing ONO-tridentate Schiff base ligands derived from 4-aminobenzohydrazide: synthesis, spectral characterization, and application as efficient homogeneous catalysts for selective sulfoxidation

Novel dioxomolybdenum complexes containing ONO-tridentate Schiff base ligands derived from 4-aminobenzohydrazide: synthesis, spectral characterization, and application as efficient homogeneous catalysts for selective sulfoxidation

Titanium(IV) complex containing ONO-tridentate Schiff base ligand: Synthesis, crystal structure determination, Hirshfeld surface analysis, spectral characterization, theoretical and computational studies

A novel titanium(IV) complex (Ti(L)2) with tridentate ONO-donor Schiff base ligand (H2L(E)-4-amino-N'-(3-ethoxy-2-hydroxybenzylidene)benzohydrazide) was synthesized. The synthesized H2L ligand and Ti(L)2 complex were characterized by various spectroscopic techniques like FT-IR, 1H NMR, 13C NMR and elemental analysis (CHN). The single crystal X-ray diffraction (SC-XRD) was also accomplished to ensure the exact molecular structure of the complex. The geometry around the central metal ion in the complex was distorted octahedral as revealed by the data collected from diffraction studies. Hirshfeld surface analysis, QTAIM, MEP and NCI calculations were carried out to explore deeply into the nature and types of the non-covalent interactions. Moreover, theoretical calculations of the Schiff base complex were carried out by DFT at B3LYP/Def2-TZVP level of theory, which showed good correlation with the experimental findings.

Synthesis, characterization, crystal structures, Hirshfeld surface analysis, DFT computational studies and catalytic activity of novel oxovanadium and dioxomolybdenum complexes with ONO tridentate Schiff base ligand

For the first time, two new oxovanadium and dioxomolybdenum Schiff base complexes, VOL(OMe) and MoO2L, were synthesized through the reaction of a ONO tridentate Schiff base ligand (H2L) derived from the condensation of 5-bromosalicylaldehyde and nicotinic hydrazide with oxo and dioxo acetylacetonate salts of vanadium and molybdenum, [VO(acac)2 and MoO2(acac)2], respectively. The synthesized ligand and complexes were characterized by various spectroscopic techniques like FT-IR, 1H NMR, 13C NMR, elemental analysis (CHN) and the most authentic single crystal X-ray diffraction analysis (SC-XRD). The geometry around the central metal ion in MoO2L was distorted octahedral as revealed by the data collected from diffraction studies. Non-covalent interactions that are responsible for crystal packing are explored by Hirshfeld surface analysis. Theoretical calculations of the synthesized compounds, carried out by DFT at B3LYP/Def2-TZVP level of theory, indicated that the calculated results are in agreement with the experimental findings. Moreover, the catalytic activities of both complexes were investigated for the selective oxidation of benzylic alcohols using urea hydrogen peroxide (UHP) in acetonitrile.

A new and efficient high-performance electrochemical glucose sensor based on a metallopolymer derived from a cobaltate (III) Schiff base complex

Through a simple and effective reaction of the cobalt (II) acetate tetrahydrate with a new ONO-tridentate Schiff base ligand (L1), which contains a thiophenyl group, a mono-anionic complex of formula: [{4-Th-C6H4-C(O)CH-C(CH3)=N-C6H4-2-O}2Co]-[Bu4N]+ (C1) was isolated. Spectroscopic tools (1H and 13C NMR, FT-IR) and the crystal structure revealed that C1 consists of a mononuclear six-coordinate anionic Co(III) center with a pseudo-octahedral geometry, and one tetrabutylammonium counterion to satisfy the negative charge of the coordination entity [CoIII(L1)2]-. Electropolymerization of C1 produces a conductive metallopolymer deposit on fluorine-doped tin oxide (FTO) electrodes, which acts as an efficient glucose sensor, showing a linear amperometric response for glucose within a concentration range of 1.97 × 10 −7 M to 3.88 × 10−6 M (R2 = 0.993), limit of detection (LOD) of 9.27 × 10−7 M and limit of quantification (LOQ) of 9.24 × 10−6 M. This electrochemical sensor, which exhibit excellent reproducibility in the manufacturing process, was stable in environmental conditions and showed good reproducibility of the measurements for two weeks. In addition, the metallopolymer deposit was characterized by electrochemical techniques (cyclic voltammetry) and SEM microscopy.

Ligand role on insulin-mimetic properties of vanadium complexes. Structural and biological studies

The syntheses of 16 vanadium(IV and V) complexes with ONO tridentate Schiff base ligands are described. The vanadium(IV) compounds were synthesized with 1,10-phenantroline as a co-ligand. In the case of five complexes of vanadium(V), the solvent molecule in form of ethanol or ethoxy ligand fill the coordination sphere of V(V) to six. In the crystal structure of selected complexes the mixture of isomers in 1:1 ratio in the unit cell is observed as the ligand is not symmetrical and forms both 5- and 6-membered rings in complex. All complexes were characterized also by elemental analysis, IR and UV–Vis spectroscopy, magnetic and cyclic voltammetry measurements. The stability of the complexes in DMSO-H2O mixture was performed at pH = 7.0 and 2.0. The relationship between phosphatase inhibition and cytotoxicity of the compounds and the key role of organic ligands in enhancing biological activity of vanadium complexes was also discussed.

Synthesis, spectroscopic, biological activities and DFT calculations of nickel(II) mixed-ligand complexes of tridentate Schiff bases

Ni(II) mixed-ligand complexes of [NiLNH3] (where L= N-salicylidene-o-aminophenol (L1), N-(5-methoxysalicylidene-o-aminophenol) (L2) and N-(2-hydroxy-1-naphthalidene)-o-aminophenol) (L3) containing ONO tridentate Schiff bases and ammonia were synthesized and characterized by elemental analysis, infrared, ultraviolet-visible, proton and carbon-13 spectroscopies. Theoretical calculations were also performed on the optimized structures of the Ni(II) mixed-ligand complexes. The Infrared and ultraviolet-visible spectra of the complexes were calculated, and the results compared with the corresponding experimental spectra to augment the experimental structural identification. The elemental analysis data confirmed the formation of 1:1:1 [metal: Schiff base: ammonia] molar ratio. The NMR spectra showed that the Schiff bases coordinated to the Ni(II) ion via the two deprotonated phenolic oxygen and azomethine nitrogen atoms. The biological studies showed that the complexes exhibited higher antibacterial and antioxidant activities than the free Schiff base ligands.

Vanadium(V) and Molybdenum(VI) Complexes Containing ONO Tridentate Schiff Bases and Their Application as Catalysts for Oxidative Bromination of Phenols

AbstractCondensation of 2,4‐dihydroxyacetophenone with isonicotinoyl hydrazide and nicotinoyl hydrazide in an equimolar ratio in methanol results in the formation of two stable ONO donor ligands, H2dhap‐inh (I) and H2dhap‐nah (II), respectively. These ligands react with [VIVO(acac)2] (Hacac=acetylacetone) in 1:1 molar ratio to give the corresponding neutral dioxidovanadium(V) complexes, [VVO2(Hdhap‐inh)] (1) and [VVO2(Hdhap‐nah)] (2), after overnight aerial oxidation in the presence of K2CO3. In the absence of K2CO3, they result in (μ‐O){bisoxidovanadium(V)} complexes, [{VVO(dhap‐inh)}2(μ‐O)] (3) and [{VVO(dhap‐nah)}2(μ‐O)] (4). Treatment of neutral dioxidovanadium(V) complexes,1and2, with H2O2yields oxidoperoxidovanadium(V) complexes K[VVO(O2)(dhap‐inh)(H2O)] (5) and K[VVO(O2)(dhap‐nah)(H2O)] (6). The ligands also react with [MoVIO2(acac)2] in 1:1 molar ratio to form [MoVIO2(dhap‐inh)]n(7) and [MoVIO2(dhap‐nah)]n(8). The reaction of oxidoperoxidomolybdenum(VI) species, generated in situ by the reaction of MoO3with H2O2with ligandsIandII, gives the oxidoperoxidomolybdenum(VI) complexes, [MoVIO(O2)(dhap‐inh)(MeOH)] (9) and [MoVIO(O2)(dhap‐nah)(MeOH)] (10), respectively. All synthesized complexes are characterized by elemental analysis, thermogravimetric, electrochemical, spectroscopic (IR, UV–Vis,1H,13C and51V NMR) and single crystal X‐ray diffraction (for1,2and8). Complexes are explored as catalysts for the oxidative bromination of phenol, a model oxidative halogenation reaction, in the presence of HClO4and KBr, using 30% H2O2as oxidant. Under optimized reaction conditions, the product selectivity follows the order: 4‐bromophenol>2‐bromophenol, both for molybdenum and vanadium complexes. Products characterized by GC analysis showed very good conversion of phenol.

SYNTHESIS, SPECTROSCOPIC, ANTIBACTERIAL AND ANTIOXIDANT ACTIVITIES OF Pd(II) COMPLEXES CONTAINING TRIDENTATE SCHIFF BASES

Pd(II) complexes of the form [PdLNH3] (where L = N-salicylidene-o-aminophenol (L1), N-(5-methoxysalicylidene-o-aminophenol) (L2) and N-(2-hydroxy-1-naphthalidene)-o-aminophenol) (L3) containing ammonia and ONO tridentate Schiff bases were synthesized. These complexes were characterized by elemental analysis, infrared, ultraviolet-visible, proton and carbon-13 spectroscopies. The NMR spectra showed that the Schiff bases coordinated to the palladium(II) ion through the two deprotonated phenolic oxygen and azomethine nitrogen atoms. The presence of ammonia molecules in these complexes were indicated by the IR and 1H NMR spectra. The spectral data suggested a square planar geometry for the complexes. The biological studies revealed that the complexes displayed better antibacterial and antioxidant activities than the parent Schiff bases.

Synthesis, structure and properties of V(IV) complex with N’-[(E)-(2,3-dihydroxyphenyl)metylidene]-2-phenylacetohydrazide

The synthesis and physicochemical properties of new vanadium(IV) complex of formula [VO(L)(phen)] is described. The L denotes ONO tridentate Schiff base derived from 2,3-dihydroxybenzaldehyde and phenylacetic hydrazide, while phen = 1,10-phenanthroline used as a co-ligand to stabilize the V(IV) oxidation state. The single crystal X-Ray crystal structure indicates on octahedral geometry of vanadium centre, with 1,10-phenanthroline nitrogen trans to the V=O bond. The complex crystalizes in a monoclinic P21/c space group, very unusual is that only one isomer is present in the crystal structure. The structure is stabilized by very weak hydrogen bonds and H···π and π···π interactions. The phenyl ring of hydrazide is strongly curved from ONO ligand plane by 70.95˚. The spectroscopic characterization (IR, UV-Vis) as well as the cyclic voltammetry measurements are presented and discussed.

Synthesis, structure and properties of V(V) monooxido complex with ONO tridentate Schiff base

The oxidovanadium(V) Schiff base complex of formula [VO(L)(EtO)(EtOH)] (where H2L = Schiff base ligand derived from 5-methoxysalicylaldehyde and phenylacetic hydrazide) was synthesized and described. Complex crystalizes in triclinic P-1 space group. Octahedral geometry of the vanadium(V) centre is filed with oxido, ONO L2- ligand and two solvent molecules both in ethoxo and as neutral ethanol form. The complex is neutral, with 5- and 6-memebered ring formed by ONO ligand coordinated in octahedral plane with oxido and EtOH ligands in vertical positions. Two isomers are present in the unit cell, with different position of 5-membered ring versus vertical plane. The elemental analysis, magnetic susceptibility, thermogravimetry and spectroscopy (IR, UV-Vis) measurements were measured and are discussed. The cyclic voltammetry measurements show irreversible processes for vanadium(IV/V) redox system. Thermal stability both in a solid state (TG and SDTA measurements) as well as in solutions (at pH 7.0 and 2.0, studied by UV-Vis spectroscopy) is discussed.

Synthesis, spectral characterization, DFT calculations, antimicrobial activity and molecular docking of 4-bromo-2-((2-hydroxy-5-methylphenylimino)methyl)phenol and its V(V) complex

VO(acac)2 reacted with a new ONO tridentate Schiff base, 4-bromo-2-((2-hydroxy-5-methylphenylimino)methyl)phenol, (H2L) in methanol to afford a new V(V) complex, [VO(L)(MeO)(MeOH)]. Characterization by elemental analysis, molar conductivity, FT-IR, electronic spectroscopy, 1H NMR, single crystal X-ray and TGA studies indicated that the free ligand existed as its keto tautomer in solid state, while in the complex it was coordinated to the regular VO core in its deprotonated form (enol), as a tridentate anionic ligand. The vanadium center was also found to be 6-coordinated, in a distorted octahedral fashion with a deprotonated ligand and an oxygen atom of the methoxy group in the equatorial plane and an oxido ligand and an oxygen from methanol in the apical sites. DFT and NBO calculations were additionally performed and confirmed the experimental data. The synthesized ligand and its oxido-vanadium(V) complex exhibited satisfactory antimicrobial activities against some tested Gram-positive and Gram-negative bacteria, and fungus strain. In addition, the potential of these compounds as antimicrobial agents was investigated using molecular docking to glucosamine-6-phosphate (GlcN-6-P) synthase.

OH-substituted tridentate ONO Schiff base ligands and related molybdenum(VI) complexes for solvent-free (ep)oxidation catalysis with TBHP as oxidant

Molybdenum complexes with ONO tridentate Schiff base ligands based on salicylideneaminophenolato (SAP) backbone with OH substitution on the salicyl arene ring have been synthesized and characterized. The molecular structures of the full series of OH substituted molybdenum complexes were determined by X-ray crystallography as monomers stabilized by one solvent molecule, [MoO2L(D)]. All dimeric complexes [MoO2L]2 were tested for the epoxidation of cyclooctene and cyclohexene under organic solvent-free conditions using aqueous TBHP as oxidant. The position of the OH on the SAP-modified ligand influenced the catalytic activity of the respective complexes. DFT calculations for the catalytic cycle yield energy spans in agreement with the experimentally observed activity trend.

Synthesis, spectroscopic, coordination and biological activities of some transition metal complexes containing ONO tridentate Schiff base ligand

The main target of this paper is to get an interesting data for the preparation and characterizations of metal oxide (MO) nanoparticles using H2L Schiff base complexes as precursors through the thermal decomposition procedure. Five Schiff base complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) metal ions were synthesized from 2-[(2-hydroxy-naphthalen-1-ylmethylene)-amino]-benzoic acid new adduct (H2L). Theses complexes were characterized using infrared, electronic, mass and 1H NMR spectroscopic techniques. The elemental analysis data was confirmed that the stoichiometry of (metal:H2L) is 1:1 molar ratio. The molar conductance indicates that all of complexes are non electrolytic. The general chemical formulas of these complexes is [M(L)(NH3)]·nH2O. All complexes are tetrahedral geometry. The thermal decomposition behavior of H2L hydrated and anhydrous complexes has been discussed using thermogravimetric analysis (TG/DTG) and differential thermal analyses (DTA) under nitrogen atmosphere. The crystalline phases of the reaction products were checked using X-ray diffractometer (XRD) and scanning electron microscopy (SEM).

Four-coordinate nickel(II) and copper(II) complex based ONO tridentate Schiff base ligands: synthesis, molecular structure, electrochemical, linear and nonlinear properties, and computational study.

We report the synthesis, characterization, crystal structures, nonlinear-optical (NLO) properties, and density functional theory (DFT) calculations of nickel(ii) and copper(ii) complex based ONO tridentate Schiff base ligands: two mononuclear compounds, [Ni(An-ONO)(NC5H5)] (5) and [Cu(An-ONO)(4-NC5H4C(CH3)3)] (6), and two heterobimetallic species, [M(Fc-ONO)(NC5H5)] (M = Ni, 7; Cu, 8), where An-ONOH2 (3) and Fc-ONOH2 (4) are the 1 : 1 condensation products of 2-aminophenol and p-anisoylacetone and ferrocenoylacetone, respectively. These compounds were characterised by microanalysis, FT-IR and X-ray crystallography in the solid state and in solution by UV-vis and (1)H and (13)C NMR spectroscopy. The crystal structures of 3-5, 7 and 8 have been determined and show for Schiff base complexes 5, 7 and 8 a four-coordinated square-planar environment for nickel and copper ions. The electrochemical behavior of all derivatives 3-8 was investigated by cyclic voltammetry in dichloromethane, and discussed on the basis of DFT-computed electronic structures of the neutral and oxidized forms of the compounds. The second-order NLO responses of 3-8 have been determined by harmonic light scattering measurements using a 10(-2) M solution of dichloromethane and working with a 1.91 μm incident wavelength, giving rather high β1.91 values of 350 and 290 × 10(-30) esu for the mononuclear species 5 and 6, respectively. The assignment and the nature of the electronic transitions observed in the UV-vis spectra were analyzed using time-dependent (TD) DFT calculations. They are dominated by LMCT, MLCT and π-π* transitions.

Doubly phenoxide-bridged binuclear copper(II) complexes with ono tridentate schiff base ligand: Synthesis, structural, magnetic and theoretical studies

The tridentate ONO-donor Schiff base ligand H2L, derived from the condensation of 1-anisyl-1,3-butanedione and 2-aminophenol, was generated in situ and reacted with Cu(NO3)2·3H2O to yield two doubly phenoxo bridged di-copper(II) complexes depending on the nitrogenous base used. [Cu2L2] (1) is obtained in 85% and 75% yield in the presence of pyridine or 4-picoline, respectively, and [(py-tBu)2Cu2L2] (2) is isolated in 75% yield in the presence of 4-tert-butylpyridine. Compounds 1 and 2 were characterized in the solid-state by elemental analysis and FT-IR spectroscopy. Single crystal X-ray diffraction study reveals that in 1 the two four-coordinated copper atoms adopt a square planar geometry, whereas in 2 each Cu(II) metal ion shows a five coordinate square pyramidal (ONO,N+O) geometry. In each dimer, two μ-phenolic oxygen atoms bridge the two half-units forming a planar Cu2O2 core. EPR studies in fluid solutions indicate that the dimeric structure of 1 and 2 is destroyed upon dissolution. In the solid-state, 1 is EPR silent, whereas 2 presents an unresolved broad resonance (ΔH peak-to-peak=71.5G) with g=2.071 at 298K, along with the triplet state (S=1) signature at g=4.181. Variable temperature (2–300K) magnetic susceptibility measurements exhibit strong antiferromagnetic interactions between the Cu(II) centers with a J value of −397cm−1 for 1, while no interaction operates between the two spins localized on Cu(II) metal ions in 2. Ab initio calculations were also performed to supplement the experimental results.

Synthesis, X-ray crystal structure, DFT calculation and catalytic activity of two new oxido-vanadium(V) complexes containing ONO tridentate Schiff bases

Two new oxido-vanadium(V) complexes, [VO(L1)(EtO)] (1) and [VO(L2)(2-BuO)] (2) [H2L1=2-{(5-chloro-2-hydroxyphenyl)iminomethyl}phenol and H2L2=4-bromo-2-{(2-hydroxy-5-methylphenyl] iminomethyl}phenol], have been prepared by the reaction of VO(acac)2 with the ONO tridentate salicylidene Schiff bases H2L1 and H2L2, and fully characterized by FT-IR, molar conductivity, elemental analyses, 1H NMR and electronic spectra. The structures of the complexes have also been determined by X-ray diffraction. Computational studies were performed at the B3LYP/6-311G(d,p) level. Furthermore, the catalytic activity of these compounds was investigated for a multicomponent reaction of cyclic enaminoketones, malononitrile and aromatic aldehydes.

Synthesis, structural characterization and antibacterial activity of diorganotin(IV) complexes with ONO tridentate Schiff bases containing pyridine ring

Abstract Five organotin(IV) complexes, were obtained by reaction of SnR 2 Cl 2 (R = Ph, Me, Bu) with ONO donor Schiff bases. The synthesized complexes have been investigated by elemental analysis and IR, 1 H NMR, and 119 Sn NMR spectroscopy. These data show that the Schiff base acts as a tridentate dianionic ligand and coordinates via the imine nitrogen and two oxygen atoms. The X-ray crystallography of complex 4 shows a dimeric structure for this molecule. The in vitro antibacterial activities of the Schiff bases and their complexes have been evaluated against Gram-positive ( Bacillus subtilis and Staphylococcus aureus ) and Gram-negative ( Escherichia coli and Pseudomonas aeruginosa ) bacteria and compared with the standard antibacterial drugs.

Synthesis, spectral studies, thermal behavior, and antibacterial activity of Ni(II), Cu(II), and Zn(II) complexes with an ONO tridentate Schiff base

Abstract Three new transition metal complexes have been synthesized with a Schiff base, 3-(2-hydroxy-5-chlorophenylimino)-1,3-diphenylpropen-1-one. In all complexes Schiff base is completely deprotonated and coordinated to metal as tridentate ligand via phenolic and enolic oxygens and imine nitrogen. Thermal decomposition of the complexes has been studied by thermogravimetry. The in vitro antibacterial activity of Schiff bases and their complexes has been evaluated and compared with the standard drugs.