Nickel Complexes Research Articles

Compounds with Chelating 3-Dimethylamino-1-propyl Ligands as Chemical Vapor Deposition Precursors. Synthesis and Characterization of M[(CH2)3NMe2]2 Complexes of Nickel(II), Palladium(II), and Platinum(II)

Compounds with Chelating 3-Dimethylamino-1-propyl Ligands as Chemical Vapor Deposition Precursors. Synthesis and Characterization of M[(CH₂)₃NMe₂]₂ Complexes of Nickel(II), Palladium(II), and Platinum(II)

Formation of a Metallomacrocycle Possessing Nitrogen Donors Assembled in the Cavity and Unique Water Clusters.

2,2'-Bipyridyl (bpy) is widely used as a chelating unit for metal complexation but is not usually considered as a hydrogen-bonding unit. This is because the metal-free bpy units are usually in a transoid conformation, and the two nitrogen lone pairs are pointed to the opposite sides. We now report a metallomacrocycle whose three metal-free bpy units are in a cisoid conformation and are fixed in the cavity. The complexation of nickel(II) only at the salen units of the triangular bpytrisalen ligand produced this rigid and planar macrocycle. Its cavity is surrounded by hydrogen-bond acceptors (N of bpy and O of salen), and it was found that unique pentagonal prism clusters of water molecules templated by the cavity were formed in the crystal. This study has not only increased the variation of the synthetic methodologies of multinuclear complexes but has also provided the structural platform on which multiple bpy units exert hydrogen-bonding functions.

Novel Octahedral Nickel (II) Complex with Flexible Piperazinyl Moiety Exhibits Potent Cytotoxic Effect Along with Anti-Migratory and Anti-Metastatic Effect on Human Cancer Cells.

Synthesis of non-platinum transition metal complexes with N,O donor chelating ligand for application against pathogenesis of cancer with higher efficacy and selectivity is currently an important field of research. We assessed the anti-cancer effect of a mixed ligand Ni(II) complex on human breast and lung cancer cell lines in this investigation. Mononuclear mixed ligand octahedral Ni(II) complex [NiIIL(NO3)(MeOH)] complex (1), with tri-dentate phenol-based ligand 2,4-dichloro-6-((4-methylpiperazin-1-yl) methyl) phenol (HL) along with methanol and nitrate as ancillary ligand was prepared. Piperazine moiety of the ligand exists as boat conformation in this complex as revealed from single crystal X-ray study. UV-visible spectrum of complex (1) exhibits three distinct d-d bands due to spin-allowed 3 A2 g→3T1 g (P), 3 A2 g→3T1 g(F) and 3 A2 g→3T2 g(F) transitions as expected in an octahedral d8 system. Our study revealed that Complex (1) induces apoptotic cell death in mouse and human cancer cells such as mcf-7, A549 and MDA-MB-231 through transactivation of p53 and its pro-apoptotic downstream targets in a dose dependent manner. Furthermore, complex (1) was able to slow the migratory rate of MDA-MB-231 cells' in vitro as well as epithelia -mesenchymal transition (EMT), the key step for metastatic transition and malignancy. Over all our results suggest complex (1) as a potential agent in anti-tumor treatment regimen showing both cytotoxic and anti-metastatic activity against malignant neoplasia.

The First Example of Dicubane Nickel(II) Complex in the Series of Unsymmetrically Substituted Diketones

The First Example of Dicubane Nickel(II) Complex in the Series of Unsymmetrically Substituted Diketones

Bioactive benzhydrazone derived Schiff base and its metal(II) complexes: Synthesis, characterisation, cytotoxicity, DNA binding/cleavage, antimicrobial and antioxidant activity

Bivalent mononuclear transition metal complexes of cobalt, nickel, copper and zinc were synthesized from (E)-2-(1-(2-(2-hydroxybenzoyl)hydrazono)ethoxy)benzoic acid. The FTIR, 1H NMR, 13C NMR, HR-Mass, UV–Vis., EPR, Powder XRD and SEM analysis were employed to investigate the structural features of synthesized compounds. The spectral data confirmed the square planar geometry of the complexes. The EPR spectra of the Cu(II) complex supported the proposed geometry. Powder X-ray diffraction (PXRD) analysis and scanning electron microscopy (SEM) imaging revealed that the complexes consist of nano-sized grains exhibiting a polycrystalline structure. The in vitro antimicrobial efficacy of the compounds was evaluated against various bacterial and fungal strains using the well diffusion method. The in vitro antibacterial activity demonstrated that all synthesized compounds were biologically active, and Zn(II) complex exhibited the highest inhibitory activity against S. aureus (gram-positive bacteria). For antioxidant activity, the free ligand and its metal chelates were evaluated using the standard DPPH method, revealing that the Co(II) complex displayed least inhibitory concentration value (IC50 = 16 ± 2.3 μg/mL) indicating the highest antioxidant activity. DNA interaction studies showed intercalation between complexes and DNA, and the Cu(II) complex exhibited a higher binding affinity of 2.78 ± 0.34 × 105 M−1. The DNA cleavage ability of the compounds was assessed using gel electrophoresis, demonstrating the effective cleavage of the pBR322 plasmid DNA. The Schiff base and its complexes were subjected to an anticancer evaluation against the human breast cancer cell line (MCF-7) using the MTT assay method. The percentage cell inhibition of the compounds was calculated.

Advancing photopolymerization and 3D printing: High-Performance NiII complexes bearing N2O2 Schiff-base ligands as photocatalysts

New high-performance photocatalysts based on metal structures are being developed for polymerization. However, using low-cost metals while ensuring effectiveness is challenging. In this study, two NiII complexes NiL1 and NiL2 were synthesized using N2O2 Schiff-base ligands bearing π-extended rings (naphthaldehyde (H2L1) and phenylsalicylaldehyde (H2L2) groups), respectively. These complexes were characterized by FTIR, UV–Vis and 1H NMR spectroscopy, elemental analysis, cyclic voltammetry, and MALDI-TOF mass spectrometry. NiL1 and NiL2 were evaluated in photoinitiating system as new photocatalysts for the Free Radical Photopolymerization of Ethoxylated (3) Trimethylolpropane Triacrylate (TMPETA) for violet and green light. Three-component systems were employed in the presence of Di-tert-butyl-diphenyl iodonium hexafluorophosphate (Iod) and ethyl dimethylaminobenzoate (EDB). The absorption, luminescence, and redox properties of nickel complexes and ligands were explored and compared for a better understanding of their structure/reactivity relationship. The designed nickel complexes showed good photoinitiation abilities. NiL2 exhibited the highest monomer conversion, and it was investigated in the on–off process under green light irradiation, demonstrating the efficiency of the system in reactivating the polymerization process. An oxidative pathway mechanism was proposed based on free energy, steady state photolysis and electron spin resonance spin trapping experiments. The best system was successfully applied in cationic photopolymerization and 3D printing.

Comprehensive Exploration of Optics and Magnetism in a Hydrothermally Synthesized Nickel(II) Complex.

The hydrothermal reaction of 2-MeIm (2-MeIm: 2-methylimidazole) with nickel sulfate hexahydrate in methanol afforded a mononuclear complex formulated as [Ni(SO4)(2-MeIm)2(H2O)3]·CH3OH (1). The title compound was described by X-ray single-crystal diffraction, thermal assessment, IR, and UV-vis spectroscopy. The crystal structure of 1 is composed of segregated [Ni(SO4)(2-MeIm)2(H2O)3] neutral entities and a solvent methanol molecule. Two (2-MeIm) ligands, a sulfate group, and a water molecule reside in the equatorial positions of the vertices in this 6-fold coordination. Two aqua ligands lay in the apical positions, resulting in a subtly distorted octahedral framework, as was supported by spectroscopic analysis. The complex's self-assembly is firmly governed by robust O-H···O/N-H···O interactions. Further details on these bonds have been furnished via Hirshfeld surface scrutiny and 2D fingerprint plots. As proven by TGA/DSC analysis, raising the temperature of 1 above 60 °C instigates progressive decomposition stages, which culminates in the production of metal oxide as the ultimate product at 700 °C. The optical analysis suggests the dielectric nature of the material with large direct and indirect gap energies of 5.25 and 4.96 eV, respectively. The results of magnetic studies suggest that 1 undergoes a transition to a magnetically ordered state below 6 K.

Asymmetric 2,3-Addition of Sulfinylamines with Arylboronic Acids Enabled by Nickel Catalysis.

Sulfinamides have been widely used in organic synthesis, with research on their preparation spanning more than a century. Despite advancements in catalytic methodologies, creating sulfur stereocenters within these molecules remains a significant challenge. In this study, we present an effective and versatile method for synthesizing a diverse range of S-chirogenic sulfinamides through catalytic asymmetric aryl addition to sulfinylamines. By utilizing a nickel complex as a catalyst, this process exhibits impressive enantioselectivity and can incorporate various arylboronic acids at the sulfur position. The resulting synthetic sulfinamides are stable and highly adaptable, allowing for their conversion to a variety of sulfur-containing compounds. Our study also incorporates detailed experimental and computational studies to elucidate the reaction mechanism and factors influencing enantioselectivity.

Fe3O4@PEG Core-Shell Nanosphere Anchored and Stabilized by Nickel Complex on Murexide: Green Synthesized Nanocatalyst with Super Catalytic Activity for Synthesize of Benzothiazole Derivatives

Fe3O4@PEG Core-Shell Nanosphere Anchored and Stabilized by Nickel Complex on Murexide: Green Synthesized Nanocatalyst with Super Catalytic Activity for Synthesize of Benzothiazole Derivatives

Catalytic ethylene oligomerization reactions of terpyridine (NNN)-based nickel(II) complexes – Studies on catalytical intermediates

The present work demonstrates the synthesis of four new terpyridine (tpy) ligands (4′-(4-(pent-4-en-1-yloxy)phenyl)-2,2′:6′,2″-terpyridine (3), 4-((3-([2,2′:6′,2″-terpyridin]-4′-yl)phenoxy)methyl)benzonitrile (4), 4′-(3-(pent-4-en-1-yloxy)phenyl)-2,2′:6′,2″-terpyridine (5), and 4-([2,2′:6′,2″-terpyridin]-4′-yl)phenyl 5-chlorothiophene-2-carboxylate (6)), the corresponding Ni(II) complexes (3C–6C), and their usage as catalysts in ethylene oligomerization reactions. The purity of all the ligands and the complexes employed in the present study was assessed by various analytical and spectroscopic techniques. One of the tpy-Ni(II) complexes (6C) was structurally characterized by single-crystal XRD analysis. Notably, the nature of ligands as well as temperature strongly influence the organic product distribution, i.e. elevated temperatures facilitate C6 product in significant amounts. Among all the complexes, the Ni(II)-tpy (6C) substituted with 5-chloro-thiophenyl group at 4′ position showed high selectivity for 1-hexene (C6, 80%) at room temperature and 1-octene (C8, 91%) at elevated temperatures. Though both mechanistic pathways were proved to be feasible, the present study is also intended to identify and analyze the key intermediate species of the reactions. In order to shed more light on mechanistic aspects, ethylene insertion reactions were compared with selected platinacycloalkane complexes in a high-pressure autoclave reactor, and the formation of large metallacycloalkane species was observed in the mass spectral data.

Aroylhydrazone‐based nickel(II) complexes: Synthesis and their structural, density functional theory (DFT), biological and catalytic studies

Nickel(II) complexes of tridentate NNO donor aroylhydrazones, viz., di‐2‐pyridyl ketone‐4‐methoxybenzhydrazone monohydrate (DKMBH·H2O) and 2‐acetylpyrazine‐4‐methoxybenzhydrazone monohydrate (APMBH·H2O), were synthesized and characterized using various methods, including spectral techniques (Fourier transform infrared [FT‐IR], UV–vis) and analytical methods (elemental and X‐ray diffraction [XRD] analysis). Single‐crystal XRD was used to elucidate the crystal structures of nickel(II) complexes 1 and 2. The XRD analysis revealed that the respective ligands coordinated to the Ni(II) center through the deprotonated iminolate form in complex 1 and the neutral amido form in complex 2, resulting in distorted octahedral geometries. The ground state electronic configurations of the complexes were studied using the B3LYP/UB3LYP levels of DFT. Using absorption spectral titration methods, the interactions of complexes with CT‐DNA and bovine serum albumin (BSA) protein were examined. The observed data demonstrate that the complexes adopt an intercalative binding mode to bind to CT‐DNA and BSA protein. Additionally, the antioxidant activity of the nickel(II) complexes and their ligands was determined using 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH). Complex 2 demonstrated the highest radical scavenging activity of the compounds studied (IC50 = 3.81 mM). Furthermore, molecular docking studies were performed to understand how the complexes can interact with the SARS‐CoV‐2 main protease. The results revealed that complex 2 had the highest docking score (−8.18 kcal/mol) when compared with the other complexes under study. Aside from their biological properties, the nickel complexes heterogenized on functionalized SBA‐15 showed promising catalytic activity, achieving 98% yield in the reduction of nitrobenzene, forming exclusively aniline as the end product.

Nickel and Oxo-Vanadium Complexes of Adenine on Modified Mesoporous MCM-41 as Chemoselective, Efficient, and Reusable Catalysts in the Oxidation of Sulfides and Oxidative Coupling of Thiols.

A highly efficient superior catalyst of Ni (II) and VO (IV) metal complexes supported on MCM-41 has been synthesized and developed for chemoselective oxidation of sulfides to sulfoxides and oxidative coupling of thiols to their corresponding disulfides using H2O2 as a green and efficient procedure. All sulfoxides and disulfides were obtained in short reaction times with excellent yields. The over-oxidation of sulfides or thiols was not observed and all products were synthesized in high purity. These catalysts could be recovered and reused several times without any significant loss in their catalytic activity. Compared to the old catalysts in the literature, these catalysts showed better activity and selectivity for the synthesis of sulfoxide and disulfide derivatives, which shows the novelty of this work. At first, the mesoporous MCM-41 was synthesized, and further, its surface was modified by (3-chloropropyl)-triethoxysilane (CPTES). Then, the modified MCM-41 (nPrCl-MCM- 41) was functionalized by adenine. In the next step, the functionalized MCM-41 (6AP-MCM- 41) was used as support for the immobilization of nickel and oxo-vanadium as final catalysts (Ni-6AP-MCM-41 or VO-6AP-MCM-41). The structure and properties of these catalysts have been identified by XRD, SEM, TGA, FT-IR, and AAS spectral analyses. These catalysts were used in the chemoselective oxidation of sulfides and oxidative coupling of thiols. These complexes catalyzed all reactions well at room temperature. According to the results obtained, the hydroxyl groups of some derivatives, including 2-(methylthio) ethanol or 2,2-(phenylthio) ethanol, remained unchanged during the reaction. The method has been found to possess the advantages of low cost, high efficiency, high yields, recovery, and reusability for several runs without significant loss in the catalytic activity.

Recent Advances in Nickel Catalysts with Industrial Exploitability for Copolymerization of Ethylene with Polar Monomers.

The direct copolymerization of ethylene with polar monomers to produce functional polyolefins continues to be highly appealing due to its simple operation process and controllable product microstructure. Low-cost nickel catalysts have been extensively utilized in academia for the synthesis of polar polyethylenes. However, the development of high-temperature copolymerization catalysts suitable for industrial production conditions remains a significant challenge. Classified by the resultant copolymers, this review provides a comprehensive summary of the research progress in nickel complex catalyzed ethylene-polar monomer copolymerization at elevated temperatures in the past five years. The polymerization results of ethylene-methyl acrylate copolymers, ethylene-tert-butyl acrylate copolymers, ethylene-other fundamental polar monomer copolymers, and ethylene-special polar monomer copolymers are thoroughly summarized. The involved nickel catalysts include the phosphine-phenolate type, bisphosphine-monoxide type, phosphine-carbonyl type, phosphine-benzenamine type, and the phosphine-enolate type. The effective modulation of catalytic activity, molecular weight, molecular weight distribution, melting point, and polar monomer incorporation ratio by these catalysts is concluded and discussed. It reveals that the optimization of the catalyst system is mainly achieved through the methods of catalyst structure rational design, extra additive introduction, and single-site catalyst heterogenization. As a result, some outstanding catalysts are capable of producing polar polyethylenes that closely resemble commercial products. To achieve industrialization, it is essential to further emphasize the fundamental science of high-temperature copolymerization systems and the application performance of resultant polar polyethylenes.

Ball-Milling toward Nickel(II) Diphosphine Complexes for Direct Use in Catalysis.

Mechanochemistry turned out to be apowerful synthetic tool enabling the first efficient synthesis of nickel(II) complexes with diphosphines. It has been demonstrated that solventless ball-milling of nickel(II) halides with diphosphines leads to the [NiX2(diphosphine)] type compounds, which can be directly used in catalysis without any purification. Moreover, it was confirmed that despite the presence of impurities in the resulting complexes, their catalytic activity remains identical to those obtained via traditional solvent-based methods.

Synthesis, crystal structure study, characterization, and DFT investigation of a new nickel(II) complex, [dihomopiperazine nickel (II)] sulfate tetrahydrate

A new nickel (II) complex [NiL2](H2O)4(SO4), where L = 1,4-diazepane, has been synthesized by interaction between nickel sulfate and 1,4-diazepane. This complex crystallizes in the Pmcn orthorhombic unit cell with parameters a = 9.173(2) Å, b = 11.691(2) Å, c = 17.015(2) Å, V = 1824.9(5) Å3, and Z = 4. It possesses a mononuclear structure in which the central NiII atom is coordinated by four N atoms from two 1,4-diazepane ligands in a distorted square-planar geometry. In the crystal, the anions [SO4]2−, the cations [NiL2]2+, and the water molecules are held together by H-bonding to form a 2D supramolecular structure. Differential scanning calorimetry (DSC) results showed that this compound undergoes a reversible order–disorder phase transition at 486 K with a hysteresis of 32 K. In addition, electrical conductivity measurements showed that the complex has a conductivity value of 4.15 10−4 Ω−1cm−1 at 390 K. The Density Functional Theory (DFT) study results qualitatively supported the experimental data obtained by X-ray diffraction and thermogravimetric analysis (TGA).

Spotlight on Zinc: Exploring the Visible Light Responsiveness of Zinc Complexes.

Group 12 element zinc(II)-based d10 complexes have long been known for their inherent colorlessness, which has limited their applications in visible light-driven photophysical and photochemical applications, despite the attractiveness of inexpensive and low-toxicity zinc metal. Based on precedents with nickel(0) and copper(I) complexes, which also adopt the d10 electronic configuration, achieving a visible light response from zinc(II) complexes seems feasible; however, investigations and proactive design strategies specifically tailored to zinc remain lacking. In this context, the present invited concept paper highlights zinc's potential for visible light responsiveness and evaluates how molecular designs can achieve this capability. After delineating the differences between zinc and other d10 metal centers, we review recent developments in zinc complexes that exhibit visible light absorption and compare these complexes with previously reported colorless complexes to identify key distinctions. This study provides critical insights into the molecular design guidelines that are pivotal for harnessing the emerging potential of zinc for visible light responses.

Six-coordinated complexes of Co(II), Ni(II) and Cu(II) chlorides with N-propargylimidazoles: Synthesis, structure, antimicrobial activity, AIM analysis and molecular docking

New six-coordinated N-propargylimidazole complexes with cobalt(II), nickel(II) and copper(II) chlorides, [M(N-propargylimidazole)4Cl2], were obtained in good yields by the reaction of N-propargylimidazole with corresponding metal chlorides. Molecular and crystal structures of compounds 1–3 were studied by X-ray analysis. Numerous non-covalent interactions including halogen bonds and π-stacking forms in the crystal were analyzed in the framework of quantum theory Atom in molecules. An evaluation of the antimicrobial activity of N-propargylimidazole complexes with Co(II), Ni(II) and Cu(II) chlorides in relation to E. durans, B. subtilis and E. coli showed that the complexes of nickel exhibit antimicrobial activity comparable to gentamicin in relation to E. coli. To explore the inhibitory activity mechanism the molecular docking was carry out.

Exploring Raloxifene-Based Metallodrugs: A Versatile Vector Combined with Platinum(II), Palladium(II) and Nickel(II) Dichlorides and Carborates against Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) poses challenges in therapy due to the absence of target expression such as estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). Frequently, the treatment of TNBC involves the combination of several therapeutics. However, an enhanced therapeutic effect can be also achieved within a single molecule. The efficacy of raloxifene can be improved by designing a raloxifene-based hybrid drug bearing a 2,2'-bipyridine moiety (2). Integration of platinum(II), palladium(II), and nickel(II) complexes into this structure dramatically changed the cytotoxicity. The platinum(II) dichloride complex 3 did not demonstrate any activity, while palladium(II) and nickel(II) dichloride complexes 4 and 5 exhibited various cytotoxic behavior towards different types of hormone-receptor positive (HR+) cancer and TNBC cell lines. The replacement of the two chlorido ligands in 3-5 with a dicarbollide (carborate) ion [C2B9H11]2- resulted in reduced activity of compounds 6, 7, and 8. However, the palladacarborane complex 7 demonstrated higher selectivity towards TNBC. Furthermore, the mechanism of action was shifted from cytotoxic to explicitly cytostatic with detectable proliferation arrest and accelerated aging, characterized by senescence-associated phenotype of TNBC cells. This study provides valuable insights into the development of hybrid therapeutics against TNBC.

Monodentate Phosphinoamine Nickel Complex Supported on a Metal-Organic Framework for High-Performance Ethylene Dimerization.

Ethylene dimerization is an efficient industrial chemical process to produce 1-butene, with demanding selectivity and activity requirements on new catalytic systems. Herein, a series of monodentate phosphinoamine-nickel complexes immobilized on UiO-66 are described for ethylene dimerization. These catalysts display extensive molecular tunability of the ligand similar to organometallic catalysis, while maintaining the high stability attributed to the metal-organic framework (MOF)scaffold. The highly flexible postsynthetic modification method enables this study to prepare MOFs functionalized with five different substituted phosphines and 3 N-containing ligands and identify the optimal catalyst UiO-66-L5-NiCl2 with isopropyl substituted nickel mono-phosphinoamine complex. This catalyst shows a remarkable activity and selectivity with a TOF of 29000 (molethyl/molNi/h) and 99% selectivity for 1-butene under ethylene pressure of 15bar. The catalyst is also applicable for continuous production in the packed column micro-reactor with a TON of 72000 (molethyl/molNi). The mechanistic insight for the ethylene oligomerization has been examined by density functional theory (DFT) calculations. The calculated energy profiles for homogeneous complexes and truncated MOF models reveal varying rate-determining step as β-hydrogen elimination and migratory insertion, respectively. The activation barrier of UiO-66-L5-NiCl2 is lower than other systems, possibly due to the restriction effect caused by clusters and ligands. A comprehensive analysis of the structural parameters of catalysts shows that the cone angle as steric descriptor and butene desorption energy as thermodynamic descriptor can be applied to estimate the reactivity turnover frequency (TOF) with the optimum for UiO-66-L5-NiCl2. This work represents the systematic optimization of ligand effect through combination of experimental and theoretical data and presents a proof-of-concept for ethylene dimerization catalyst through simple heterogenization of organometallic catalyst on MOF.

Physicochemical studies on prepration, structure and bonding of Ni(II) complexes with N,O and S containing ligands

Transition metal complexes of Nickel (II) with nitrogen, Oxygen, and sulphur doners such as thiocarbohydrazido, thio-cyanato, thiosemicarbazido and water are characterized based on structural, magnetic, and spectral data. These complexes have been thoroughly investigated using the physicochemical method. The present work deals mainly with the study of preparation, bonding, and structures with magnetic and spectral properties in Nickel (II) complexes. The bonding is based on the valence bond theory. The magnetic susceptibility of these complexes is observed using Gau balance methods and spectral properties are based on NMR Spectro metre. Keywords:- Nitrogen, Sulphur, complexes, Nickel chloride, Magnetic properties, Structure. Spectral.