Bidentate Schiff Base Research Articles

Synthesis, Characterization, Biological Evaluation, DFT, and Molecular Docking Study of a Co(II) Complex Derived from ON Donor Bidentate Schiff Base Ligand

AbstractThe utilization of biologically active metal complexes in medicine is gaining recognition as an alternative approach to traditional biologically active organic molecules, which often exhibit undesirable side effects. This study focuses on the synthesis and characterization of a Co(II) complex derived from the (E)‐2‐((2‐hydroxybenzylidene)amino)‐5‐methylbenzonitrile ligand system (HL) and cobalt(II) acetate tetrahydrate in a dichloromethane/methanol solution. A comprehensive characterization strategy was employed, involving proton and carbon nuclear magnetic resonance, infrared, electronic spectra, PXRD, SEM‐EDX, and mass spectroscopies, as well as elemental analysis (CHN and Co), TGA, and molar conductance, to confirm the chemical structures of the ligand and its complex. The infrared spectral data revealed the ligand as a bidentate ligand, chelating the Co(II) ion through the oxygen and nitrogen atoms of the phenolate and imine groups. Additionally, PXRD and SEM analyses indicated crystalline and amorphous properties for the ligand and complex, respectively. Assessment of antimicrobial potential using a modified disc diffusion method, with streptomycin as the positive control, demonstrated the complex's enhanced antibacterial activity compared to the ligand against all tested bacteria, showing a concentration‐dependent response. Similarly, antioxidant studies revealed promising results, with the complex exhibiting superior DPPH radical scavenging activity (IC50 values: ligand 64.5 μg.mL−1, complex 43.1 μg.mL−1). Theoretical analysis through DFT calculations and molecular docking provided insights into the electronic properties and binding affinity of the ligand and complex, supporting the experimental findings and affirming the biological activities exhibited by the compounds. Overall, this research showcases the synthesis, characterization, and biological evaluation of a promising Co(II) complex, highlighting its potential as an effective antimicrobial and antioxidant agent.

Synthesis, structural elucidation, and antibacterial activities of novel copper(II), cobalt(II), and nickel(II) complexes with a bidentate Schiff base ligand against pathogenic bacteria

Novel Schiff base metal complexes diaqua(4-chloro-2-{[(4-(dimethylamino)phenyl)methylene]amino}phenolato)M(II) ion, (M = copper/cobalt/nickel) have been synthesized using the ligand 4-chloro-2-((4-(dimethylamino)benzylidene)amino)phenol, which was prepared by reacting 2-amino-4-chlorophenol with 4-(dimethylamino)benzaldehyde in a molar ratio of 1:1. The synthesized compounds were characterized based on elemental analysis, FTIR, UV–vis., 1H and 13C NMR, powder XRD, mass spectrometry and magnetic studies. Spectroscopic investigations demonstrated that the metal atom coordinates to a bidentate Schiff base ligand via the azomethine nitrogen and phenolic oxygen. The appropriate molecular geometry for each metal complex has been proposed through the analysis of spectroscopic and analytical data, Specifically, tetrahedral geometry has been proposed for Co(II), Ni(II), and square planar geometry for Cu(II) complex. Theoretical calculations employing Density Functional Theory (DFT) validated the experimental results, elucidating optimized geometries, frontier molecular orbitals, natural bond orbital distributions, molecular electrostatic potentials, non-linear optical properties, IR vibrational modes, and UV absorbance profiles. Additionally, the compounds' biological efficacy was validated through molecular docking against receptors for Gram(+ve) bacteria, Bacillus subtilis (PDB ID: 5H67), Staphylococcus aureus (PDB ID: 3TY7) and Gram(-ve) bacteria, Escherichia coli (PDB ID: 3T88), Proteus vulgaris (PDB ID: 5I39). The outcome revealed that Co(II) complex exhibited highest binding energy with Escherichia coli and Bacillus subtilis while the ligand with Proteus vulgaris (5I39) and Staphylococcus aureus (3TY7). Further the study was extended to the MD Simulation in water for 100 ns to evaluate the binding affinities and its stabilities by analyzing the deviation, fluctuations, and intermolecular interactions. The research presented here showcase the potential of employing a Schiff base ligand and its Co(II) complex in the synthesis of novel, highly potent antibacterial agents to combat emerging diseases, which holds considerable importance in the field of pharmaceutical science—however, in-vitro studies are needed to validate the results.

Spectroscopic, anti-cancer, anti-bacterial and theoretical studies of new bivalent Schiff base complexes derived from 4-bromo-2,6-dichloroaniline

In this paper, four new mono-nuclear Ni(II), Pd(II), Pt(II) and Zn(II) complexes were prepared by using a bi-dentate Schiff base ligand, (E)-2-(((4-bromo-2,6-dichlorophenyl)imino)methyl)-5-chlorophenol (BrcOH), with bivalent ions in a methanol and distil water mixture as solvent in presence of NaOH as base. The structures of the prepared compounds were characterized by spectroscopic techniques (IR and 1H NMR), CHN analysis, and molar conductivity. The M(II) (Ni, Pd and Pt) ions are four-coordinated by a bi-dentate N2O2 donor ligand, forming square planar geometry, whereas the Zn(II) is coordinated as a tetrahedral geometry. The newly synthesized compounds, which include the Schiff base ligand and its complexes, underwent antibacterial screening against E. coli and S. aureus. The results demonstrated a remarkable and noteworthy biological activity of these compounds against these pathogenic bacterial strains. Different binding energies showed good correlation, with Pd showing the strongest binding. Small energy differences indicated high reactivity, with Ni and Pd complexes being the most reactive. Electrophilicity index exhibited electron-accepting properties, with Zn showing the highest reactivity. The dipole moments showed polarity and charge separation, with Pt having the highest polarity. We evaluated the pharmacokinetic properties (ADME) of a ligand and its metal complexes using the Swiss ADME website. The results of the in-silico prediction of physicochemical properties revealed that ten compounds in total adhered to Lipinski's rule.

Salicylaldehyde salicyloyl hydrazone and its copper(II) complex: synthesis, characterization, DFT, optical band gap, antibacterial activity, and molecular docking analysis

A complex of Cu(II) with a bidentate Schiff base, salicylaldehyde salicyloyl hydrazone (SSH), was synthesized by refluxing copper(II) chloride with this ligand. The formation of the complex, the nature of bonding, and the geometry of the complex were established via physicochemical and spectroscopic techniques. The composition of the complex was found to be a 1:2 metal-ligand ratio as Cu(SSH)2. Electronic absorption spectral studies revealed that the copper adopts a distorted tetrahedral geometry upon complexation with SSH. The optical band energy for the complex was determined from absorption spectroscopy. The obtained band gap of 2.66 eV characterizes the complex as a semiconductor. The most stable conformations of the Schiff base (SSH) and Cu(SSH)2 complex have been computed, shedding light on their structural and electronic properties, and highlighting their potential reactivity and stability. The ligand exhibits a higher reactivity towards electrophiles, while the complex displays a greater affinity for nucleophiles. The in vitro antibacterial analysis with agar cup well method and in silico molecular docking analysis indicate that both the ligand and its complex with copper have potency to inhibit bacterial infections. Based on their growth inhibition, minimum inhibitory concentration (MIC) values, and robust interaction with studied proteins of the pathogens, these compounds hold a prospective avenue for the advancement of antibiotics.

Design, structural characterization, DFT, molecular docking, and chemotherapeutic activity of novel platinum(II) and palladium(II) complexes derived from Metformin-based Schiff base

Two novel bidentate Schiff bases ligands derived from Metformin with aldehydic molecules, including o-Ethoxy benzaldehyde (L1) and thiophene-2-carbaldehyde (L2) and Pt(II) and Pd(II) complexes were prepared. Numerous techniques were used to study the ligands and their metal complexes, including mass spectroscopy, IR, UV–Vis, molar conductivity, magnetic moment measurement, 1HNMR, PXRD, and 13CNMR. The preceding two Schiff bases were coordinated to Pd (II) and Pt (II) in the molar ratio of (1:1) (M:L) with the molecular structure [MLCl2]. The chemical quantum characteristics were calculated, and Schiff bases' optimized geometric structures and their complexes were revised theoretically. The MCF-7 breast cancer model was used to test the anticancer effects of metformin Schiff bases and their complexes in vitro. Additionally, using the EGFR tyrosine kinase of the selected proteins, a molecular docking study was carried out to learn more about the docking active site interactions. Ultimately, the conventional DPPH method was used to assess the antioxidant activity of the free ligands and their metal chelates. Pt (II) complexes demonstrated greater free radical scavenging activity than ascorbic acid. Furthermore, Pt (II) complexes showed more effective interactions with the selected mTOR protein, which is assumed to help the COVID-19 virus proliferate. Thus, Pt (II) has a bright future in the realm of chemotherapy.

Antifungal and antibacterial activity of two new Ni(II) complexes of a pyrazole-appended thiophene containing bidentate schiff-base ligand: Synthesis, spectroscopy and crystal structures

A new pyrazole-appended thiophene containing Schiff-base ligand, N-(thiophene-2-ylmethyl)-1-(5-methyl-1H-pyrazol-3-yl)methanimine, (MPATA) (1) and its two new di- and mononuclear Ni(II) complexes, [Ni2(MPATA)4 (µ-Cl)2]Cl2 (2) and [Ni(MPATA)3](ClO4)2 (3), respectively, are reported. All the synthesized compounds have been thoroughly characterized by several physico-chemical and spectroscopic studies. Single crystal X-ray diffraction studies have identified 2 as a chloro‑bridged di-nuclear cationic complex, while 3 as a mononuclear distorted octahedral one. In 2, coordination to each metal centre has been occurred by two molecules of ‘NN’ bidentate MPATA and each Ni(II) centre assumes a distorted octahedral geometry. On the other hand, in 3, three molecules of the ‘NN’ bidentate MPATA coordinate to the Ni(II) centre. Both the complexes 2 and 3 exhibit significant hydrogen bonding and intramolecular π···π stacking interactions. All the three compounds have been found to display significant antifungal activity against plant pathogen funguses Colletotrichum siamense (CS) and Fusarium equisetum (F.E) and antibacterial activity against gram-positive and gram-negative bacteria, but no such effects have been found against human pathogen fungus Candida albicans sc5314.

Zn(II), Mn(III), and Co(III) complexes of Schiff base derived from 2‐hydroxy‐1‐naphthaldehyde: Synthesis, spectral surveys, single crystal structure studies, Hirshfeld surface analysis, density functional theory calculation, molecular electrostatic potential, and molecular docking evaluations

A new series of transition metal complexes of bidentate Schiff base compound derived from 2‐hydroxy‐1‐(2‐methoxyethylimino)‐naphthalene (HL) were synthesized and characterized using elemental analysis, Fourier transform infrared spectroscopy (FT‐IR), and UV–vis spectroscopies. X‐ray single crystal structures of Zn(II), Mn(III), and Co(III) complexes (1–4) have also been determined, and it was indicated that these Zn(II) and Co(III) complexes (1, 4) are in an octahedral geometry. Whereas, it was found that the Zn complex (2) is in quite a regular tetrahedral environment. Also, the Mn center in complex (3) is ligated by two azomethine nitrogen atoms, two ligand oxygen atoms, and one Cl atom of metal salt forming five coordinated tetragonal pyramid geometry around the Mn atoms. The cyclic voltammetry of the complexes specifies an irreversible redox behavior for all complexes (1–4). Next, DFT/B3LYP theoretical method was used to determine the optimal geometrical configurations and comparison between experimental and theoretical data, as well as for calculations of molecular electrostatic potential, highest‐occupied molecular orbital (HOMO)‐lowest‐unoccupied molecular orbital (LUMO) energy values of selected compounds. The study of non‐covalent interactions was done by Hirshfeld surface analysis using CrystalExplorer program. Furthermore, molecular docking inspection was carried out to study the binding affinity of the tested complexes towards protein B‐cell lymphorna (PDB ID: 4LXD). Using the results obtained from the molecular docking and the summarized interaction of the binding processes, these structures show the validity of effective inhibition against liver cancer.

Synthesis, Spectroscopy, X-ray Structures, DNA Binding and Photocatalytic Properties of Two Ni(II) and Co(II) Complexes of a Pyrazolyl Schiff-base Ligand

Two new nickel(II) and cobalt(II) complexes, [Ni(MPAFA)3](BF4)2 (I) and [Co(MPAFA)3](BF4)2 (II) were synthesized from a pyrazole containing ‘NN’ bidentate Schiff-base ligand, N-(furan-2-ylmethyl)-1-(5-methyl-1H-pyrazol-3-yl)methanimine, (MPAFA) (L). The complexes I and II were characterized by various physico-chemical and spectral parameters. Both I and II were 1:3 (M:L) coordination complexes and behaving as 1:2 electrolytes. Single crystal X-ray diffraction studies revealed that both of them were distorted octahedral in nature with a N6 donor set. The binding interactions of the complexes with CT-DNA were studied by UV-Vis and fluorescence spectroscopic methods. I was found to bind with CT-DNA in a partial intercalative mode, whereas II bound via the groove-like manner in solutions. The ligand and the complexes were shown to have potential photocatalytic activity in degrading methylene-blue (MB) under UV-Vis light irradiation.

3-Phenoxybenzaldehyde and Glycine-Derived Schiff base M(II) Complexes: Synthesis, molecular Modeling, spectroscopic Exploration, and antimicrobial evaluation

This study synthesized a novel bidentate Schiff base known as 2-((3-phenoxybenzylidene)amino)acetic acid (HL) derived from glycine and 3-phenoxy benzaldehyde and its M(II) complexes (M = Co2+, Cu2+, Ni2+ & Zn2+) was prepared by combining the Schiff base (HL) and the metal acetates in a 1:2 ratio. The molecular structure of the Schiff base was confirmed using CHN analysis, mass, FT-IR, UV–Vis, 1H NMR and 13C NMR spectra. The prepared complexes were analyzed using CHN analysis, mass, FT-IR, UV–Vis, molar conductivity studies, magnetic susceptibility studies, and ESR for Cu(II) complexes. Based on the analysis, square planar geometry is suggested for the Cu(II) & Ni(II) complexes and tetrahedral geometry for Co(II) and Zn(II) complexes. A preliminary in vitro antimicrobial investigation of the synthesized ligand and its related complexes has been performed. The M(II) complexes showed more potent antimicrobial activity than its Schiff base; in particular, the Cu(II) complex illustrated notable inhibitory effects. Molecular docking studies were conducted against CDK2 (PDB ID: 1B39), α-amylase (PDB ID: 4W93), and α-glucosidase (PDB ID: 3TOP). The Ligand HL demonstrated AutoDock/MM-GBSA binding energy values of −5.9 /-104 kcal mol−1 (CDK2), −6.6 /-134 kcal mol−1 (α-amylase), and −7.4/ −174.84 kcal mol−1 (α-glucosidase). The complexes exhibited MM-GBSA binding energy values within the range of −198.20 to −198.72 kcal mol−1 (CDK2), −250.00 to −250.02 kcal mol−1 (α-amylase), and −279.51 to −283.84 kcal mol−1 (α-glucosidase). The molecular docking results shed light on the potential of ligand HL and its metal complexes as promising candidates for further exploration in therapeutics, particularly in targeting CDK2 inhibition (anticancer) and α-amylase and α-glucosidase inhibition (antidiabetic).

Synthesis, characterization, X-ray Crystallography, Photoluminescence property and DNA binding activity of Co(II) and Ni(II) complexes of a pyrazole-containing Schiff-base ligand

Two new complexes, [Co(MPAFA)3](ClO4)2 (1) and [Ni(MPAFA)3](NO3)2·2H2O (2), of an ‘NN’ bidentate Schiff-base ligand, N-(furan-2-ylmethyl)-1-(5-methyl-1H-pyrazol-3-yl)methanimine (MPAFA), have been synthesized and characterized by physicochemical and spectral methods such as elemental analyses, conductance, IR, UV-Vis, and emission spectra. In both complexes, three ligands coordinate with a metal ion to form 1:3 complexes. Both 1 and 2 are distorted octahedral and cationic, behaving as 1:2 electrolytes. IR spectra showed that each of the ligands coordinates via the pyrazolyl tertiary nitrogen and the azomethine nitrogen atoms. Single crystal X-ray studies confirmed CoN6 and NiN6 coordination for 1 and 2, respectively, and showed that both complexes exhibit π…π stacking and various hydrogen bonding interactions. Both 1 and 2 are fluorescent and participate in DNA binding with calf thymus DNA (CT-DNA) via groove binding.

Manganese(II) and Zinc(II) metal complexes of novel bidentate formamide-based Schiff base ligand: synthesis, structural characterization, antioxidant, antibacterial, and in-silico molecular docking study.

A new bidentate Schiff base ligand (C16H16Cl2N4), condensation product of ethylene diamine and 4-chloro N-phenyl formamide, and its metal complexes [M(C16H16Cl2N4)2(OAc)2] (where M = Mn(II) and Zn(II)) were synthesized and characterized using various analytical and spectral techniques, including high-resolution mass spectrometry (HRMS), elemental analysis, ultraviolet-visible (UV-vis), Fourier-transform infrared (FTIR) spectroscopy, AAS, molar conductance, 1H NMR, and powder XRD. All the compounds were non-electrolytes and nanocrystalline. The synthesized compounds were assessed for antioxidant potential by DPPH radical scavenging and FRAP assay, with BHT serving as the positive control. Inhibitory concentration at 50% inhibition (IC50) values were calculated and used for comparative analysis. Furthermore, the prepared compounds were screened for antibacterial activity against two Gram-negative bacteria (Staphylococcus aureus and Bacillus subtilis) and two Gram-positive bacteria (Escherichia coli and Salmonella typhi) using disk-diffusion methods, with amikacin employed as the standard reference. The comparison of inhibition zones revealed that the complexes showed better antibacterial activity than the ligand. To gain insights into the molecular interactions underlying the antibacterial activity, the ligand and complexes were analyzed for their binding affinity with S. aureus tyrosyl-tRNA synthetase (PDB ID: 1JIL) and S. typhi cell membrane protein OmpF complex (PDB ID: 4KR4). These analyses revealed robust interactions, validating the observed antibacterial effects against the tested bacterial strains.

Catalytic and biological properties of palladium(II) complexes with bidentate Schiff base ligands

In this study, we synthesized and characterized Schiff base ligands (S1–3), which contained sulfonamide/sulfonate groups, and their corresponding Pd(II) complexes (K1–3). We also introduced these complexes into Al2O3‐supported materials (M1–3) using the impregnation method. Following the structural characterization, we proceeded to evaluate the performance of the supported materials in a series of degradation and reduction reactions of involving organic pollutants. These assessments were conducted with the intention of exploring their potential as catalysts in aqueous environments in the presence of NaBH4. The study's findings present novel approaches to develop effective catalysts for reducing/degrading organic pollutants in aqueous environments. The M2 catalyst showed excellent results for dye mixing after 90 s. Additionally, we investigated the antibacterial and cytotoxic properties of the synthesized compounds. The outcome also suggests that these synthesized compounds exhibit potential antibacterial and cytotoxic properties.

Synthesis, Spectral Characterizations and Pharmacological Assay Supported by DFT Studies, Molecular Docking and ADMET Studies of Organotellurium(IV) Complexes Derived from Bidentate Schiff Base of 5-Methyl-2-Thiophene Carboxaldehyde

In the recent decade, due to the widespread distribution of infectious diseases, a significant series of compounds have been synthesized to fight these diseases. Among the different series of compounds, organotellurium(IV) complexes played a significant role in dealing with a variety of infectious diseases. In this connection, we have designed and synthesized six novel organotellurium(IV) complexes using 5-methyl-2-thiophenecarboxaldehyde (5MTCPT) Schiff base. The synthesized compounds were investigated by several spectral and computational techniques like FT-IR, 1H NMR, mass spectrometry, [Formula: see text]C NMR, TGA, SEM/EDAX, DFT and Molecular docking. The spectroscopic results apparently demonstrate that ligand depicts bidentate complexation through N and S atoms. The in vitro pharmacological interpretation of these compounds was executed as effective antimicrobial and antioxidant agents. All the designed compounds were also subjected to geometry optimization with def2-T2VPP and def2-SVP. The optimized structures were used for the molecular docking studies, and it was identified that the tellurium complexes have more effective antimicrobial and antioxidant properties than the Schiff base (5MTCPT).

Anticancer Properties of Ru and Os Half-Sandwich Complexes of N,S Bidentate Schiff Base Ligands Derived from Phenylthiocarbamide.

The versatile coordinating nature of N,S bidentate ligands is of great importance in medicinal chemistry imparting stability and enhancing biological properties of the metal complexes. Phenylthiocarbamide-based N,S donor Schiff bases converted into RuII /OsII (cymene) complexes and characterized by spectroscopic techniques and elemental analysis. The hydrolytic stability of metal complexes to undergo metal-halide ligand exchange reaction was confirmed both by the DFT and NMR experimentation. The ONIOM (QM/MM) study confirmed the histone protein targeting nature of aqua/hydroxido complex 2 aH with an excellent binding energy of -103.19 kcal/mol. The antiproliferative activity against a panel of cancer cells A549, MCF-7, PC-3, and HepG2 revealed that ruthenium complexes 1 a-3 a were more cytotoxic than osmium complexes and their respective ligands 1-3 as well. Among these ruthenium cymene complex bearing sulfonamide moiety 2 a proved a strong cytotoxic agent and showed excellent correlation of cellular accumulation, lipophilicity, and drug-likeness to the anticancer activity. Moreover, the favorable physiochemical properties such as bioavailability and gastrointestinal absorption of ligand 2 also supported the development of Ru complex 2 a as an orally active anticancer metallodrug.

Mono and binuclear cadmium complexes: X-ray crystal structures, Hirshfeld surface analysis and antimicrobial/antioxidant studies

A bidentate Schiff base ligand(L) and two new mono and binuclear cadmium(II) complexes formulated as [CdL2(NO3)](NO3) and [Cd2L2Cl4] were synthesized and their structures were characterized by physical and spectral techniques Moreover, the structures of the cadmium(II) complexes were identified using single crystal X-ray analysis. Hirshfeld surface analysis was used to characterize various interactions in the solid state framework. Thermal behaviors of the compounds were investigated from room temperature to 800 °C. Furthermore, the antimicrobial bioassays on the cadmium(II) complexes were performed in vitro against two gram-positive and two gram-negative bacterial strains and also against two fungal strains. Finally, the antioxidant capabilities of the Schiff base ligand and its complexes were investigated by means of two in vitro methods of ABTS and DPPH as compared with Trolox as a standard compound.

Development of new cobalt, copper, and zinc complexes of Schiff-base ligands as prospective chemotherapeutic agents

Fluorobenzaldehyde was converted into new, bidentate Schiff-base ligands with nitrogen and sulphur donor sites in two steps. The first step proceeds via Knoevenagel condensation; the product obtained was treated with thiosemicarbazide to yield the ligand L1. The Schiff-base ligand, L2, was synthesized by treating L1 with 4-chlorobenzylchloride in a basic medium. Co (II), Cu (II), and Zn (II) complexes were synthesized with the ligands L1 and L2. All these complexes were characterized by FTIR, UV–Vis, NMR spectroscopy, ESI-mass spectral analysis, magnetic moment, molar conductance, thermal, powder XRD, and electrochemical studies. From these studies, the molecular formulae of the complexes were found to be [M(L)2Cl2], where M = Co (II), Cu (II) and Zn (II) and L = L1 or L2 based on the ligand used in the synthesis. The synthesized complexes were observed to have a high spin and distorted octahedral geometry and were non-electrolytic. The UV absorption titrimetric analysis confirmed that these complexes would bind strongly to CT-DNA through the intercalative mode. The electrophorograms supported the statement that Cu (II) complexes could effectively catalyze the hydrolytic cleavage of CT-DNA and can be considered potent metallonuclease agents. The DPPH assay determined the antioxidant properties of these complexes, and the cupric complexes were observed to possess better antioxidant properties than the standard used ascorbic acid. The cell viability analysis of these complexes showed an elevated control of proliferation against a human breast adenocarcinoma (MCF-7) cancer cell line compared to a human cervical carcinoma (HeLa) cell line. The results exhibited by these compounds were compared with the standard drug, cisplatin. The binding affinity of the Cu (II) metal ion complex towards CT-DNA was high when compared to Co (II) and Zn (II) metal ions. These results are in line with the cytotoxicity studies. Molecular docking studies also hold up the experimental data. Cu (II) complexes using ligand L2 show higher efficiency than those with ligand L1 in all biological assays and can be considered a potent DNA-targeting drug.

Novel Zn- and Cd-Schiff base complexes as the potent anticancer agents: Synthesis, spectral characterization and theoretical study

A novel unsymmetrical bidentate Schiff base ligand and its complexes, with the common formula of MLX2 (M(II) = Zn(II) and Cd(II); X− = Cl−, Br− and I−), using a reaction between 1,2-diaminobenzene and (E)-3-(4-(Dimethylamino) phenyl) acrylaldehyde were successfully synthesized. The structure of all the as-made compounds was identified by techniques including 1H NMR,13C NMR, ESI-mass, FT-IR, UV–Vis, melting point and molar conductivity. The analytical and spectral data confirmed the metal to ligand ratio of 1:1 in the Zn(II) and Cd(II) complexes. The anticancer activity of the compounds on cancer cells was investigated on HCT116 cell line, where the MTT method was used to screen cytotoxicity effects. The flow cytometry method also was used to determine the mechanism of cell death. Our data reveal that CdLCl2 can block the cell cycle and induction apoptosis. In addition, using Gaussian 16 program, the structure of the samples was optimized, and some important properties such as enthalpy change, entropy change and total energy were extracted. The molecular electrostatic potential, nonlinear optical properties, natural bond orbital and frontier molecular orbitals analysis were calculated for all compounds. Further, the electrophilic and nucleophilic sites, energy gap, ionization potential, electron affinity, natural population analysis and natural atomic orbitals were studied.

First Report on Several NO-Donor Sets and Bidentate Schiff Base and Its Metal Complexes: Characterization and Antimicrobial Investigation

The condensation product of the reaction between aniline and salicylaldehyde was a 2-(2-hydroxybenzylidinemine)—aniline Schiff base bidentate ligand (L). L was used to generate complexes by interacting with the metal ions lanthanum(III), zirconium(IV), yttrium(III), and copper(II), in addition to cobalt(II). Various physicochemical techniques were utilized to analyze the synthesized L and its metal chelates, including elemental analysis (CHN), conductimetry (Λ), magnetic susceptibility investigations (μeff), Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR) spectroscopy, ultraviolet–visible (UV-Vis.) spectrophotometry, and thermal studies (TG/DTG). FT-IR revealed that the L molecule acted as a bidentate ligand by binding to metal ions via both the oxygen atom of the phenolic group in addition to the nitrogen atom of the azomethine group. Additionally, 1H NMR data indicated the formation of complexes via the oxygen atom of the phenolic group. An octahedral geometrical structure for all of the chelates was proposed according to the UV-Vis. spectra and magnetic moment investigations. Thermal analysis provided insight into the pattern of L in addition to its chelates’ breakdown. In addition, the investigation furnished details on the chelates’ potential chemical formulas, the characteristics of adsorbed or lattice H2O molecules, and the water that is coordinated but separated from the structure at temperatures exceeding 120 °C. The thermodynamic parameters utilizing Coats–Redfern in addition to Horowitz–Metzger equations were studied. The antimicrobial effectiveness of L and its chelates against distinct species of bacteria and fungi was studied using the disc diffusion method. Cu(II) and Y(III) chelates had significant antimicrobial activity against Staphylococcus aureus and Micrococcus luteus.

Crystal Structure and DFT Computations of a Solid-State Solution of Mixed Mononuclear Cu(II)/Co(II) Complex

<p>A<strong> </strong>novel mixed molecular Cu (II) and Co (II) complexes [Cu L<sub>2</sub>]<sub>0.82</sub> and [CoL<sub>2</sub>]<sub>0.18</sub> (1) where HL = (4-salicylaldaimine antipyrine) derived from 4-aminoantipyrine and 2-hydroxybenzaldehyde, was isolated as a green solid and characterized by Fourier Transform Infrared Spectroscopy (FTIR), Ultra-Violet Visible spectroscopy (UV-Vis) and Single-crystal x-ray diffraction. Compound 1 is a solid-state solution that contains a statistical mixture of two different molecular complexes: 82% of a 17-electron Cu (II) complex and 18% of a 15-electron Co (II) complex. By looking at the structure, it seems that the two metal ions occupy the same metal site, which is not true; at least a small distance between them exists, verified using the Density functional theory (DFT).<strong> </strong>A divalent metal cation binds four coordination sites in each molecular complex from two corresponding bidentate Schiff base ligands. Each metal atom is coordinated with two nitrogen and two oxygen atoms of the Schiff base ligand in a geometry much closer to pseudo-tetrahedral than planar. DFT calculations were used to validate the trends observed in bond lengths and angles in this structure. By using the DFT methods, it is seen that there are no significant differences in the experimental values obtained by single-crystal X-ray diffraction. It should be noted that the experimental results belong to the solid phase, while the theoretical calculations belong to the gas phase.</p>

Synthesis, Physicochemical, and Antimicrobial Activity of Copper and Zinc Complexes with N, O - Bidentate Schiff Base

This paper is intended to prepare new antimicrobial complexes with proven efficiency. The Schiff base, through the condensation process of salicylaldehyde and p-toludine, and its Cu and Zn complexes were successfully synthesized. The Schiff base and its complexes were characterized using molar conductivity, Ultraviolet-visible (UV-Vis), atomic absorption spectroscopy (AAS), and Fourier transform infrared (FTIR) techniques. Accordingly, these characterizations not only confirmed that the synthesized Schiff base acted as N,O bidentate ligand (through azomethine nitrogen and phenoxide oxygen) and chelated with Cu(II) and Zn(II) in the metal-to-ligand ratio of 1:2 but also revealed the characteristic electronic-transition of π→π*/n→π* of the ligand, and ligand-metal charge transfer and d-d of the metal complexes. Moreover, both Cu and Zn complexes recorded weak molar conductance of 54.12 and 51.41 S cm2 mol-1, respectively. Further, their antibacterial activities were evaluated by disc diffusion assay against Staphylococcus aureus (gram-positive), Escherichia coli (gram-negative), and Bacillus cereus (gram-negative) bacteria. For all microbial, the metal complexes recorded higher activities than the parent ligand; such increased activity of the complexes may be due to the chelation of the metal ion in the complexes, which enhances the lipophylic character favoring its permeation through the lipid layer of the cell membrane. Such metal complexes can therefore be explored in the future as an option for decreasing the pathogenic potential of infecting bacteria.