Ni Complexes Research Articles

Investigation of Oxidative Behaviour and Structural Insights of (3,4,5-Trimethoxyphenyl)Porphyrin Ni(II) Complex: Experimental and Theoretical Study

Investigation of Oxidative Behaviour and Structural Insights of (3,4,5-Trimethoxyphenyl)Porphyrin Ni(II) Complex: Experimental and Theoretical Study

Design and synthesis of two new thiosemicarbazide based Schiff base metal complexes of nickel (II): DNA binding study and cytotoxicity profile analysis

Two new nickel (II) substituted thiosemicarbazone Schiff base complexes [Ni(meph)2] (1) [where H2meph = (2E)-N-methyl-2-[1-(pyridin-2-yl)ethylidene]hydrazine-1-carbothioamide] and [Ni(hmm)2](NO3)2·2H2O (2) [where H2hmm = (2E)-2-[(2-hydroxyphenyl)methylidene]-N-methylhydrazine-1-carbothioamide] have been designed and synthesized by the condensation of 4-methyl-3-thiosemicarbazide with 2-acetylpyridine and salicylaldehyde respectively. Both the metal complexes 1 and 2 are characterized using different available spectroscopic techniques like FT-IR, UV–Vis spectroscopy, elemental analysis, and single crystal X-ray structure analysis. X-ray crystal structure analysis reveal that complex 1 and 2 are octahedral Ni(II) complexes. The calf-thymus CT-DNA-binding property of 1 and 2 has been evaluated by employing UV–Vis and fluorescence spectral titration. All the results show that CT-DNA binds with both nickel(II) complexes 1 and 2. In vitro cytotoxicity activity of complexes 1 and 2 toward A375 and MDA-MB-231 was evaluated using MTT assay and other methods which confirm that both complexes 1 and 2 behave as promising anti-cancer agents.

Synthesis and Characterization of Ni(II) Complex with Terephthalate and Pyrazine Mixed Ligands by Solvothermal Method

This research aims to synthesize and characterize Ni(II)-terephthalate-pyrazine complex and to determine the thermal stability and porosity profile of the synthesized compound. The Ni(II)-terephthalate-pyrazine was made by solvothermal reaction using dimethylformamide at 130 and 150 °C and in Ni(II):terephthalic-acid:pyrazine mol ratios of 1:1:2 and 1:1:4. The precipitated products were characterized by infrared spectroscopy, SEM, and powder-XRD in order to confirm the presence of both ligand in the synthesized compound. Meanwhile, the thermal stability and porosity profile of the synthesized compound were determined by DTA-TGA and surface area analysers, respectively. Experimental data shows that green pale powder was obtained from all reactions in considerably good yield, which is different from the dark green crystalline solid of Ni(II)-terephthalate. SEM image reveals that the product has a smooth-wavy surface morphology. Infrared spectra of the synthesized compound show peaks of functional groups of C=O, C–O, C=N, and C–N groups, which confirm the presence of both ligands. Powder XRD analysis suggests that the crystal system of the synthesized compound is different from that of the Ni(II)-terephthalate. Based on these analyses, the targeted Ni(II)-terephthalate-pyrazine is successfully obtained. Moreover, the synthesized compound has lower thermal stability than that of Ni(II)-terephthalate, while the BET calculation suggest that the synthesized compound has pore volume of 0.10-0.14 cm3/g, pore diameter of 8.1-10.65 nm and surface area of 24-30 (m2/g). This porosity profile suggest that the synthesized compound is open for further application, such as adsorption or photocatalysis.

Homoleptic Co(II) and Ni(II) complexes with promising anticancer and antimicrobial activities; Synthesis, X-ray structure, and DFT studies

The antimicrobial and anticancer potentials of the newly synthesized homoleptic [M(BPPT)2](ClO4)2 complexes, where M = Co or Ni, were reported. Their molecular structure aspects were investigated with the aid of elemental analysis, FTIR spectra, and X-ray crystallography. The s-triazine functional ligand (BPPT) worked as a tridentate N-chelate. With two BPPT molecules in the coordination sphere, the Co(II) and Ni(II) are hexa-coordinated with distorted octahedral configuration. The important supramolecular structural aspects were investigated using Hirshfeld topology analysis. The red spots in the dnorm map are related to the short O···H, N···H, C···H, and C···O contacts. 1 and 2 have promising antibacterial and antifungal activities against P.vulgaris (MIC = 2.5 μg/mL) and A. fumigatus (2.5 μg/mL), respectively exceeding the medications gentamycin (MIC= 5.0 μg/mL) and ketoconazole (5 μg/mL) as positive controls, respectively. In addition, 1 is better anticancer agent against HCT-116 (IC50 = 2.44±0.32 µg/mL) and A-549 (3.88±0.38 µg/mL) cell lines compared to the Ni(II) analogue (3.54±0.39 and 6.37±0.54 µg/mL, respectively). Their cytotoxic activity exceeded the efficiency of cis-platin versus both carcinoma cells (HCT-116; 8.4 ± 0.8 and A-549; 19.3 ± 0.8 µg/mL). The selectivity indices of 1 and 2 are exceeding unity indicating their availability for use as anticancer therapeutic agents.

A novel Ni-complex nanocatalyst for efficient electrochemical oxidation of alcohol in alkaline medium: Mechanism and DFT study

A novel catalyst based on nanoparticles of Ni(II) complex was developed to enhance the activity toward alcohol oxidation and hence its possible application in direct alcohol fuel cells (DAFCs). The [NiII(ABP)2] complex was formed in a molar ratio 1(Ni):2(ABP), where (ABP) was synthesized based on 4-(Dimethylamino)benzaldehyde (DMBA), 4-Aminoantipyrine (AAP) and 2-aminophenol (AP) through two condensation steps. Several characterization techniques were used to evaluate the structure of the synthesized compounds, such as elemental analysis, mass, FTIR, UV–Vis, 1HNMR , magnetic, molar conductance and XRD. Transmission and scanning electron microscope (TEM and SEM) images of separated [NiII(ABP)2] complex revealed particles with a size lower than 26 nm. SEM for [NiII(ABP)2]/GCE before and after ethanol oxidation was performed along with EDX and mapping techniques. The computational DFT (density functional theory) calculations supported the octahedral geometry shape of the prepared [NiII(ABP)2] chelate. Several octahedral structures involved in a purposed mechanism were studied using DFT to show the expected optimized shapes formed during ethanol oxidation. Also, the alcohol adsorption simulation was performed using Dmol3 numerical DFT modules to calculate the adsorption energy of alcohols on nickel complex surface. Additionally, the activity toward oxidation of alcohols with different sizes and stereochemistry (methanol, ethanol, propanol, and isopropanol) was investigated in an alkaline medium. The electrode activity was represented for each alcohol as a function of anodic oxidation current. Whereas the electrode achieved 14, 26, 6, and 4 mA cm−2 for methanol, ethanol, propanol, and isopropanol, respectively. Moreover, several parameters were calculated to judge the electrode performance, like diffusion coefficient, catalytic rate constant, stability, Tafel slope, and charge transfer resistance. The theoretical calculations and the experimental findings strongly correlate with each other, where Ni-complex showed the greatest catalytic activity toward ethanol oxidation.

Exploring the synthesis, structure and properties of two phenoxy-bridged polynuclear Cu(II) and Ni(II) complexes containing salamo-based bicompartmental ligand

A salamo-based bicompartmental ligand H4L was successfully prepared, which self-assembled with copper(II) and nickel(II) salts in stoichiometric ratios of 1:2 to construct polynuclear copper(II) and nickel(II) complexes: [Cu2(HL)(NO3)(H2O)] (1) and [Ni4(μ-HL)2(μ-OAc)2]⋅2CH3COCH3 (2). Complex 1 contains one partially deprotonated (HL)3− part, two copper(II) atoms, one coordinated monodentate nitrate ion and one coordinated water molecule. Each copper(II) center is located in the geometric structure of square pyramidal. While complex 2 is composed of four nickel(II) atoms, two ligand (HL)3− parts, and two bridging μ-OAc− anions. The differently structural complexes acquired may be attributed to the different solvents and anions used in the synthesis process. Whether or not 3-hydroxyl group of salicylaldehyde unit in H4L is involved in the coordination further influences the diversification of the structures of the complexes. The reaction sites and intermolecular interactions were further evaluated by MEPs, IRI, Hirshfeld surface and finally the fluorescence properties were explored.

High Activity Ethylene Oligomerization Using Asymmetric Alkyl P‐Substituted Bis(phosphanyl)amine Ni(II) complexes

ABSTRACTA series of novel asymmetric alkyl P‐substituted bis(phosphanyl)amine (PNP) Ph2PN (cyclopentyl) PR1R2‐type L1–L5 ligands and these corresponding Ni(II) precatalysts C1–C5 were synthesized and characterized. The structures of these complexes were confirmed by using 1H‐, 31P‐, 13C‐NMR, FT‐IR, and elemental analysis. Using ethylaluminum dichloride (EADC) as a cocatalyst, nickel complexes exhibited high activity in elective ethylene oligomerization, with the main products being dimers and a small number of trimers. Under optimized conditions of 60°C and 1.0 MPa ethylene pressure, C4, bearing a diisopropylphosphoryl group, exhibited highest catalytic activity of 1342.9 kg·g Ni−1·h−1 with 85.2% C4 and 14.8% C6 products selectivity, while C2, bearing a diethylphosphonyl group, showed catalytic activity of 596.4 kg·g Ni−1·h−1 with 88.2% C4 and 11.8% C6 product selectivity. Single crystal analysis offered a more comprehensive insight into the subtle effects of alkyl P‐substituted in the scaffold of C2 and C4 ligands on catalytic activity. Density functional theory (DFT) calculations indicated that lower energy of the LUMO in the C4A intermediate enhances the activity of ethylene oligomerization. It provides a new method for purposefully designing ligands for ethylene oligomerization with high catalytic activity.

One-Pot Sustainable Synthesis of Highly Substituted Pyrimidines via Acceptorless Dehydrogenative Annulation of Alcohols Using Pincer Ni(II)-NNS Catalysts.

We report an efficient and sustainable synthesis of highly substituted pyrimidines promoted by nickel(II)-NNS pincer-type complexes via acceptorless dehydrogenative annulations of readily available alcohols, malononitrile, and guanidine/benzamidine salt under eco-friendly conditions for the first time. Different sets of Ni(II) complexes (C1-C3) encapsulated in NNS pincer-type thiosemicarbazone ligands have been synthesized and authenticated by analytical and spectroscopic (Fourier transform infrared, nuclear magnetic resonance, and high-resolution mass spectrometry) techniques. The solid state three-dimensional structure of a representative complex (C2) has been determined with the aid of single crystal XRD analysis and confirms a square planar architecture around the nickel ion. Further, the well-defined Ni(II) complexes have been employed as efficient catalysts for the fabrication of a wide range of 4-aminopyrimidine-5-carbonitrile derivatives (33 examples) from readily available alcohols with suitable coupling partners such as malononitrile and guanidine/benzamidine under eco-friendly conditions. The current catalytic approach affords maximum yields up to 95% utilizing 3 mol % catalyst loading and water/hydrogen as the only byproduct. A feasible catalytic pathway has been proposed based on the different control experiment reactions, which clearly indicate that the coupling reaction proceeds via aldehyde and benzylidenemalononitrile intermediates. The practicability of the current protocol has been demonstrated by the large-scale synthesis of one of the products, 4-amino-2,6-diphenylpyrimidine-5-carbonitrile, and a short synthesis of a cytosine antifungal analogue.

A Robust In Vitro Anti‐tuberculosis, Antimicrobial, and Anti‐inflammatory Activities Based on Azomethine Chelates Incorporating Co(II), Ni (II), Cu(II), and Zn(II) Ions: Synthesis, Characterization, and Investigation of the Aspects of Docking Interaction

ABSTRACTIn recent times, there has been a growing exploration of transition metal complexes as potential solutions for significant health challenges, including tuberculosis, microbes infection, and inflammation. Therefore, in our ongoing effort to identify biologically effective agents, Co(II), Ni(II), Cu(II), and Zn(II) metal complexes of H2L1–H2L2 hydrazone ligands were synthesized. The structural features of synthesized compounds were recognized by employing several techniques such as FT‐IR, 1H NMR, 13C NMR, powder x‐ray diffraction (XRD), UV‐Vis, ESR, TG‐DTA, mass spectrometry, and molar conductance measurements. The bonding of ligands via Ophenolic, Oenolic, and Nazomethine donor atoms and the attachment of the three water molecules with metal ion to form the octahedral structure of complexes were corroborated by different spectroscopic techniques. The anti‐tuberculosis, antimicrobial, and anti‐inflammatory activities of the synthesized compounds were assessed using the microplate alamar blue assay, serial dilution, and bovine serum albumin (BSA) methods, respectively, and highlighted the more potency of the complexes than ligands. The synthesized Cu(II) (9) and Zn(II) (10) metal complexes exhibited excellent ability to inhibit the growth of H37Rv strain of Mycobacterium tuberculosis in comparison to standard drug streptomycin. The Cu(II) (6 and 9) and Zn(II) (10) complexes showed superb ability as antimicrobial agents, whereas Cu(II) (5) and Zn(II) (6) complexes exhibited significant anti‐inflammatory ability. The in vitro findings on the antituberculosis activity were reinforced by a significant molecular docking study, which has become a crucial component of computational research utilizing the enzyme Mtb Pks13 thioesterase domain of M. tuberculosis. Additionally, in this research work, the absorption–distribution–metabolism–excretion–toxicity (ADMET) study sparked the compounds' drug‐like behavior.

Synthesis of anthraquinone-based azo-metal(II) complexes as potent anti-oxidizing agents

The 3-diethylaminophenol (3-DEAP) incorporated anthraquinone mono-azo dye derivative [(E)-1-((4-(diethylamino)-2-hydroxyphenyl)diazenyl)anthracene-9,10-dione] DAAD was synthesized through an electrophilic substitution reaction. The interaction between the -OH functional group and the nitrogen atom of the azo moiety may result in intramolecular proton transfer in the DAAD. DAAD was treated with metal ions such as Co(II), Ni(II), and Cu(II) acetates in a ratio of 2 : 1 revealing an octahedral structure. Many analytical and spectroscopic methods, including UV-vis, FT-IR, (1H and 13C) NMR, HRMS, TGA, VSM, ESR, and powder XRD methods, were used to verify the structural characteristics of the compounds. Additionally, the potency of the in-vitro antioxidant properties of the ligand and its Cu(II), Ni(II), and Co(II) complexes were evaluated; the results revealed that the Co(II) complex showed a maximum percent inhibition of 85 μM against the standard ascorbic acid.

Synthesis, crystal Structure, theoretical calculation and luminescence properties of Cu(Ⅱ), Co(Ⅱ), Ni(Ⅱ) and Zn(Ⅱ) quinolinyl benzimidazole complexes with multiple coordination number induced by proton

The innovative ligand H2L, featuring a benzimidazole structure substituted with 8-hydroxyquinoline and equipped with N,O donor sites, underwent successful synthesis and meticulous characterization. Notably, this ligand was exclusively synthesized through catalysis under protonated conditions, accompanied by an in-depth exploration of the catalytic mechanism. Employing single-crystal X-ray diffraction, we acquired and authenticated four distinct asymmetric double-decker sandwich mononuclear transition metal complexes: [Cu(HL)2]·2H2O, [Co(HL)2]·CH3OH, [Ni(HL)2] and [Zn(HL)2]·CH2Cl2. Among these, complex 1 revealed an intriguing five-coordinate Cu(II) center adopting a distorted square pyramidal geometry, whereas the central metal ions in complexes 2–4 exhibited a six-coordinate configuration, characterized by a distorted octahedral geometry. Noteworthy is the observation that the dihedral angles within the crystal structures of complexes 2–4 approached approximately 90° to a significant extent. To delve deeper into the electronic properties and transitions, meticulous DFT and TD-DFT calculations were performed on both the ligand H2L and complexes 1–4. Furthermore, a comprehensive investigation into the luminescence properties of both H2L and its complexes was conducted, revealing a pronounced luminescence quenching effect in the complexes compared to the ligand. Through thorough analysis utilizing Hirshfeld surface examination and IRI analysis, various weak intermolecular interactions within the system were elucidated.

Oxidative and Reductive Manipulation of C1 Resources by Bio-Inspired Molecular Catalysts to Produce Value-Added Chemicals.

ConspectusTo tackle the energy and environmental concerns the world faces, much attention is given to catalytic reactions converting methane (CH4) and carbon dioxide (CO2) as abundant C1 resources into value-added chemicals with high efficiency and selectivity. In the oxidative conversion of CH4 to methanol, it is necessary to solve the requirement of strong oxidants due to the large bond-dissociation energy (BDE) of the C-H bonds in methane and achieve suppression of overoxidation due to the smaller BDE of the C-H bond in methanol as the product. On the other hand, to efficiently perform CO2 reduction, proton-coupled electron transfer (PCET) processes are required since the reduction potential of CO2 becomes positive by using proton-coupled processes; however, under the acidic conditions required for PCET, hydrogen evolution by the reduction of protons becomes competitive with CO2 reduction. Thus, it is indispensable to develop efficient catalysts for selective CO2 reduction. Recently, we have developed efficient catalytic reactions toward the alleviation of the concerns mentioned above. Concerning CH4 oxidation, inspired by metalloenzymes that oxidize hydrophobic organic substrates, a hydrophobic second coordination sphere (SCS) was introduced to an FeII complex bearing a pentadentate N-heterocyclic carbene ligand, and the FeII complex was used as a catalyst for CH4 oxidation in aqueous media. Consequently, CH4 was efficiently and selectively oxidized to methanol with 83% selectivity and a turnover number of 500. In contrast, when methanol was used as a substrate for catalytic oxidation by the FeII complex, oxidation products were obtained in a negligible yield, which was comparable to that of the control experiment without the catalyst. Therefore, the hydrophobic SCS of the FeII complex can capture only hydrophobic substrates such as CH4 and release hydrophilic products such as methanol to the aqueous medium for suppressing overoxidation ("catch-and-release" mechanism). On the other hand, for photocatalytic CO2 reduction, we have developed NiII complexes with N2S2-chelating ligands as catalysts, which have been inspired by carbon monoxide dehydrogenase, and have also introduced a binding site of Lewis-acidic metal ions to the SCS of the Ni complex. When Mg2+ was applied as a moderate Lewis acid, a Mg2+-bound Ni catalyst allowed us to achieve remarkable enhancement of the photocatalytic CO2 reduction to afford CO as the product with over 99% selectivity and a quantum yield of 11.4%. Divalent metal ions besides Mg2+ also showed similar positive impacts on photocatalytic CO2 reduction, whereas monovalent metal ions exhibited almost no effects and trivalent metal ions exclusively promoted hydrogen evolution. In this Account, we highlight our recent progress in the catalytic manipulations of CH4 and CO2 as C1 resources.

Thermodynamic Modulation of Dihydrogen Activation Through Rational Ligand Design in GeII-Ni0 Complexes.

A family of chelating aryl-functionalized germylene ligands has been developed and employed in the synthesis of their corresponding 16-electron Ni0 complexes (PhiPDippGeAr·Ni·IPr; PhiPDipp = {[Ph2PCH2Si(iPr)2](Dipp)N}-; IPr = [{(H)CN(Dipp)}2C:]; Dipp = 2,6-iPr2C6H3). These complexes demonstrate the ability to cooperatively and reversibly activate dihydrogen at the germylene-nickel interface under mild conditions (1.5 atm H2, 298 K). We show that the thermodynamics of the dihydrogen activation process can be modulated by tuning the electronic nature of the germylene ligands, with an increase in the electron-withdrawing character displaying more exergonic ΔG298 values, as ascertained through NMR spectroscopic Van't Hoff analyses for all systems. This is also shown to correlate with experimental 31P NMR and UV/vis absorption data as well as with computationally derived parameters such as Ge-Ni bond order and Ni/Ge NPA charge, giving a thorough understanding of the modulating effect of ligand design on this reversible, cooperative bond activation reaction. Finally, the utility of this modulation was demonstrated in the catalytic dehydrocoupling of phenylsilane, whereby systems that disfavor dihydrogen activation are more efficient catalysts, aligning with H2-elimination being the rate-limiting step. A density functional theory analysis supports cooperative activation of the Si-H moiety in PhSiH3.

Elucidation of mode of anticancerous activity of metal guanidinobenzimidazoles: A computational and experimental screening

DNA‐binding agents often exhibits dual behavior of simultaneous binding with protein associated with cancerous cell development pathways. This simultaneous protein binding if contributed to malfunctioning of pro‐apoptotic proteins will reduce anticancerous potential of drugs. The elucidation of binding target for anticancerous agent can give an insight into the cancer cell apoptotic pathway. Therefore, anticancerous Zn(II) and Ni(II) complexes of 2‐guanidinobenzimidazole (2GBz) were subjected to DNA‐binding mode assay along with protein‐binding interference assay. The stoichiometry Zn‐2GBz and Ni‐2GBz were determined through density functional theory (DFT) and UV–Vis spectroscopy, followed by structural verification by X‐ray crystallography. The 2GBz and Ni‐2GBz were found to bind with grooves of DNA while groove binding of Zn‐2GBz induced unwinding of DNA through interactive pi‐stacking. Binding constant revealed the M‐2GBz to be a strong binder of DNA molecule with the effect of enhanced cell killing potential of M‐2GBz against MCF‐7 cell lines. Protein‐binding assay revealed that despite of significant interaction of M‐2GBz with chick serum albumin, DNA binding was not altered by simultaneous protein binding. The most potent Zn‐2GBz was found to be sphingosine 1 kinase 2 (SPhK2) which can be a cause of enhanced cancer cell apoptosis with lesser normal cell apoptosis than standard fluorouracil in MCF‐7 cell lines. Co‐administered Zn‐2GBz increased cancer cell sensitivity towards fluorouracil as potent anticancerous agent.

Mer-[Ni(dien)2]Cl2.H2O and mer-[Ni(dien)2](NO3)2 complexes (dien= diethylenetriamine): Synthesis, physical, computational studies, antioxidant activity, and their use as precursors for Ni/NiO nanoparticles’ preparation

Two new Ni(II) complexes, mer-[Ni(dien)2]Cl2.H2O (I) and mer-[Ni(dien)2](NO3)2 (II), where dien= diethylenetriamine and mer refers to meridional coordination, have been prepared under ambient conditions. Complex (I) crystallizes in the P21/c space group of the monoclinic system, with a = 13.5000(4) Å, b = 8.7170(3) Å, c = 13.9430(4) Å, β = 102.091(2)° and V = 1604.41 Å3, whereas complex (II) crystallizes in the Pbca space group of the orthorhombic system, with a = 8.8117(6) Å, b = 14.0023(8) Å, c = 26.7603(17)Å and V = 3301.79 Å3. Both structures contain the [Ni(C4H13N3)2]2+ cation, together with two chloride anions and a water molecule for (I) and two nitrate anions for (II). The metal centre is coordinated to six nitrogens of the neutral dien ligands in a slightly distorted octahedral geometry. The two compounds have been characterised by FTIR and UV-Vis spectroscopy. Their morphology and size were studied by scanning electron microscopy (SEM). The thermal behaviour of the title compounds was also investigated. Calcination of the two complexes in air yielded Ni/NiO nanoparticles. The structures of both complexes were optimised and their simulated geometric parameters and vibrational modes were discussed and correlated with the experimental data. The antioxidant potential of both complexes was evaluated using DPPH, ferric reducing power tests and phosphomolybdenum assay.

Recyclable Ni(II), Cu(II), and Co(II) complexes containing Schiff base immobilized on nanosilica as catalysts in oxidation of hydrocarbons

Metal complexes (M=Ni, Cu, and Co) containing Schiff base have been synthesized and characterized using the usual coordination chemistry techniques. The complexes were immobilized in silica nanoparticle functionalized with a Schiff base (SB) and the heterogeneous catalysts were characterized by infrared spectroscopy, Scanning electron microscopy (SEM) and determination of the surface area (BET). Thermogravimetric analysis (TGA) of metal concentration was conducted using atomic absorption spectroscopy. The catalysts were studied in the oxidation reaction of hydrocarbons at 50 °C using H2O2 or tert-butyl hydroperoxide (TBHP) as oxidant. The heterogeneous catalysts NPs-SiO2-SB-Co(II) (catalyst 1), NPs-SiO2-SB-Cu(II) (catalyst 2), and NPs-SiO2-SB-Ni(II) (catalyst 3) showed moderate activities in the oxidation of cyclohexane, toluene, and benzene using H2O2 as oxidant. The results indicated that catalyst 2 displayed better activity in the oxidation of cyclohexane, toluene, and benzene. The best activity was obtained at 50 °C with the following conversions: 88 %, 78 %, and 66 % for cyclohexane, toluene and benzene, respectively. The results of the recycling experiment revealed that the copper complex immobilized in mesoporous silica nanoparticle maintains its catalytic activity after 4 cycle.

Direct Access to Benzolactams and Benzolactones via Nickel Catalyzed Carbonylation with CO2.

A new nickel catalyzed cross-electrophile coupling for accessing γ-lactams (isoindolinones) as well as γ-lactones (isobenzofuranones) via carbonylation with CO2 is documented. The protocol exploits the synergistic role of redox-active Ni(II) complexes and AlCl3 as a CO2 activator/oxygen scavenger, leading to the formation of a wide range of cyclic amides and esters (28 examples) in good to high yields (up to 87 %). A dedicated computational investigation revealed the multiple roles played by AlCl3. In particular, the simultaneous transient protection of the pendant amino group of the starting reagents and the formation of the electrophilically activated CO2-AlCl3 adduct are shown to concur in paving the way for an energetically favorable mechanistic pathway.

Synthesis, structural, biological applications, DFT, molecular docking studies on Fe(III), Co(II), and Ni(II) complexes incorporating 2‐(pyridin‐2‐yl)phenol and 1H‐benzimidazole‐2‐carboxylic acid

This study provides a detailed investigation into the synthesis, characterization, and biological activities of the coordination compounds FePPHBZC, CoPPHBZC, and NiPPHBZC. These compounds were synthesized with high yields by reacting chloride salts of Iron, Cobalt, or Nickel with 2‐(pyridin‐2‐yl)phenol (PPH) and 1H‐benzimidazole‐2‐carboxylic acid (BZC) in a 1:1:1 ratio. Various techniques including spectroscopic (IR, UV–vis, mass spectra), elemental analysis, conductivity, magnetic, and thermal analyses confirmed the formation and structure of these coordination compounds. Density functional theory (DFT) calculations were used to study their electronic structure, stability, and reactivity. 3D modeling revealed hexacoordinated geometries for Fe and Co complexes and a tetrahedral coordination for the Ni complex. Analysis of the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), and other reactivity parameters indicated changes in reactivity upon metal coordination. Molecular Electrostatic Potential (MEP) diagrams identified electron‐rich areas prone to nucleophilic attack, important for protein interactions during docking studies. Biological evaluations demonstrated that metal–ligand complexes exhibit enhanced antimicrobial, antioxidant, and anti‐inflammatory activities compared to individual ligands, with larger inhibition zones and higher inhibitory activity. Molecular docking studies showed strong interactions between metal–ligand complexes and target proteins, suggesting potential therapeutic applications. Among them, FePPHBZC exhibited the strongest interactions, followed by CoPPHBZC and NiPPHBZC, characterized by hydrogen bonding, ionic interactions, and other non‐covalent interactions, contributing to their enhanced stability and binding affinity.

Towards Construction of the “Periodic Table” of 1-Methylbenzotriazole

Metal complexes of benzotriazole-type ligands continue to attract the intense interest of many inorganic chemistry groups around the world for a variety of reasons, including their aesthetically beautiful structures, physical properties and applications. 1-methylbenzotriazole (Mebta) is the N-substituted archetype of the parent 1H-benzotriazole. The first attempt to build a “periodic table” of Mebta, which includes its complexes with several metal ions, is described in this work. This, at first glance, trivial ligand has led to interesting results in terms of the chemistry, structures and properties of its metal complexes. This work reviews the to-date published coordination chemistry of Mebta with Mn(II), Fe(II), Fe(III), Co(II), Ni(II), Cu(I), Cu(II), Zn(II), Pd(II), Au(I) and {UVIO2}2+, with emphasis on their preparations, reactivity, structures and properties. Unpublished results from our group comprising other Co(II), Ni(II), Cu(II) and Zn(II) complexes, as well as Cd(II), Hg(II), Ag(I), In(III) and Sn(IV) ones are briefly reported. Mebta can also provide access to 1D and 3D heterometallic thiocyanato-bridged Co(II)/Hg(II) and Ni(II)/Hg(II) compounds. In almost all cases, Mebta behaves as a monodentate ligand with the nitrogen of position 3 of the azole ring as the donor atom. However, there are two copper complexes in which this molecule adopts a bidentate bridging coordination behavior. Our efforts to complete the “periodic table” of Mebta are continued.

Biological evaluation of a novel Schiff base ligand as an antioxidant agent: Synthesis, characterization and DFT computations of its Ni(II) and Cu(II) complexes

By condensation reaction in methanolic medium, a novel ligand using methoxy substituted amine and 5-bromosalicylaldehydic was synthesized. Then, its Cu- and Ni- complexes were also prepared under same experimental conditions. The final desired compounds, with high obtained yields, have been characterized and well discussed by EA-CHN, UV–Vis., FT-IR, NMR, SEM-EDX and MS spectrometry. The structure of the ligand was confirmed by X-ray crystallography showing an interesting intramolecular hydrogen bond and also intermolecular interactions (Br…CArom. and CH/π-type). The electronic properties were quantified by density functional theory (DFT) calculations using DFT- B3LYP/6-31 G (d,p) level basis set. The molecular structures, geometrical parameters, chemical reactivity, stability, molecular electrostatic potential (MEP) and Mulliken atomic charges were computed to identify the chemical reactive sites on the molecular surface. The antioxidant activities were studied theoretically involving various parameters such as bond dissociation enthalpy (BDE), ionization potentials (IPs), proton affinities (PA), proton dissociation enthalpy (PDE), electron transfer enthalpy (ETE) and radical stabilization energy (RSE). Experimentally, the antioxidant activities were also studied by using 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), ferric ion reducing antioxidant power (FRAP) and nitric oxide scavenging (SNP) methods. The computational study of antioxidant activity is well correlated with their experimental results.