Ni Base Research Articles

ANTIMICROBIAL, ANTIOXIDANT AND CYTOTOXICITY STUDY OF Cu(II), Zn(II), Ni(II), AND Zr(IV) COMPLEXES CONTAINING O, N DONOR SCHIFF BASE LIGAND

Objective: The aim of the research is to synthesize and characterize Cu(II), Zn(II), Ni(II), and Zr(IV) complexes with a Schiff base ligand, and evaluate their antibacterial and antioxidant properties. Methods: The ligand was synthesized by refluxing salicylaldehyde with o-phenylenediamine in ethanol, forming a yellow-orange product. The complexation reaction involved stirring ethanolic solutions of Zn(II), Cu(II), Ni(II), or Zr(IV) salts with a Schiff base ligand. Thermal decomposition of Zn(II), Cu(II), Ni(II), and Zr(IV) complexes was analyzed under nitrogen, heating at 30 °C/min, measuring weight loss from ambient temperature to 800 °C. The antibacterial activity, antioxidant properties, and cytotoxicity of the synthesized compounds wereexamined using reported methods. Results: Cu(II), Zn(II), Ni(II), and Zr(IV) complexes with a Schiff base ligand were synthesized. Analyzed through Fourier-transform infrared spectroscopy (FTIR), Ultraviolet-visible (UV-vis) and physiochemical tests and confirmed the structures. Magnetic susceptibility and electronic spectra suggested geometries, supported by thermogravimetric data. Antibacterial tests revealed complexes had higher activity than ligands, and also showed antioxidant properties. Conclusion: Cu(II), Zn(II), Ni(II), and Zr(IV) Schiff base complexes were synthesized, showing tetrahedral or square planar geometries. They exhibited thermal stability and strong antibacterial activity, outperforming the ligand alone.

Novel Ni(II) and Zn(II) Schiff base metal chelates as promising DNA binder, Antioxidant and Antifungal agents

<p>Schiff base ligands and their 3d-metal chelates have gained significant attention due to various applications in various scientific platforms. Due to their chelating propensity, they possess a wide range of biological, biochemical, catalytic, clinical, dying, and pharmacological properties.<strong> </strong>Here, in present studies,<strong> </strong>two novel Ni(II) and Zn(II) transition metal chelates have been synthesized by condensing their metal salts with Schiff base ligand 4-chloro-2-(2,5-dimethoxybenzylideneamino)-5-nitrophenol<strong> </strong>originated from 2,5-dimethoxybenzaldehyde and 2-amino-4-chloro-5-nitrophenol. The synthesized Schiff base ligand and its metal chelates have been Spectro-chemically examined by FT-IR, UV-Vis absorption spectroscopy, Mass Spectrometry, <sup>1</sup>HNMR, Thermogravimetric analysis (TGA) and Powdered-XRD. These compounds are biologically reactive and exhibit antifungal, antioxidant, and DNA-binding activity. The Ni(II) metal chelate gives better biological activity than the Zn(II) metal chelate and parent Schiff base ligand.</p>

Effect of alloy 625 buffer layer on corrosion resistance of nickel base hardfacing

Nickel base hardfacing alloys serve to mitigate corrosion losses at elevated temperatures. Efficacy of Nickel base hardfacing alloys can be compromised when applied onto Fe base substrates due to iron dilution in hardfacing. The degree of Fe dilution can be reduced by using advanced deposition methods and optimized deposition parameters. Gas Tungsten Arc Welding (GTAW) method is commonly employed for its cost-effectiveness and versatility, but it tends to induce higher Fe dilution due to increased heat input. This study aims to reduce the degree of Fe dilution and enhance corrosion resistance by introducing a nickel base buffer layer (alloy 625) between the nickel base hardfacing alloy and AISI 316L stainless steel substrate. For comparative purposes, Ni base hardfacing alloy was deposited on the substrate without any buffer layer. Hardfacing depositions were prepared using manual GTAW process. Process parameters namely, deposition current, voltage, travelling speed, pre-heating temperature, and cooling method were kept constant. Samples underwent aging at 1123 K for 4 h, followed by microstructural examination via optical and scanning electron microscopes. Iron (Fe) dilution quantification was performed using energy dispersive spectroscopy (EDS). The EDS analysis showed that the use of buffer layer between the hardfaced deposit and the substrate decreased the degree of Fe dilution in the hardfaced deposit. X-Ray diffraction (XRD) analysis was performed to identify various phases formed in the hardfaced deposit. Potentiodynamic polarization test was performed to assess the corrosion resistance of hardfaced deposit in 3.5 wt% NaCl solution. Results show significant improvement in corrosion resistance of hardfacings deposited sample with buffer layer as compared to those without buffer layer. Aging treatment further enhanced corrosion resistance. The corrosion resistance data is correlated with the microstructure and phases formed in various samples.

DNA interaction, biological, and structural identification studies of bivalent nano‐sized Nickel, Palladium, and Platinum chelates of 2‐(((Z)‐6‐chloro‐3‐((E)‐([2‐hydroxyphenyl]imino)methyl)‐4H‐chromen‐4‐ylidene)amino)phenol Schiff base ligand

New nano‐sized Ni(II), Pd(II), and Pt(II) Schiff base chelates of 2‐(((Z)‐6‐chloro‐3‐((E)‐([2‐hydroxyphenyl]imino)methyl)‐4H‐chromen‐4‐ylidene)amino)phenol were designed and manufactured. The structural characterization of these isolated compounds was accomplished through spectral measurements, thermal and elemental analyses, and magnetic moment and conductivity determinations. The nano‐sized metal(II) complexes molar conductance indicated that they exhibited non‐electrolytic behavior. The UV–Vis spectral data and magnetic moment provided evidence for producing octahedral geometries in the nano‐sized complexes of Ni(II), Pd(II), and Pt(II). Metal chelates' thermal characteristics and decomposition kinetics were examined through Coats‐Redfern technique. The kinetic aspects, including pre‐exponential factor (A), the entropy of activation (ΔS), and activation energy (E) were enumerated. The X‐ray diffraction (XRD) calculations results of the trivalent metal complexes showed that sharp and intense diffraction peaks signify their crystalline properties with nanoscale particle size, and another proof was obtained from the images of SEM, TEM, EDX, and AFM also homogeneous distribution over the complex surface was confirmed. Molecular modeling techniques were adopted to optimize the metal complexes geometry. The viscosity and UV–Vis absorption determinations were utilized to assess the calf thymus DNA (CT‐DNA) interaction with the nano‐sized metal(II) chelates. The acquired data revealed that the complexes exhibit a non‐intercalative or incomplete binding pattern when interacting with DNA. The calculated DNA‐complexes binding constants are 3.93 ± 0.02 × 10,4 1.67 ± 0.3 × 105 and 2.88 ± 0.03 × 105 M−1, for nano‐sized Ni(II), Pd(II) and Pt(II) Schiff base chelates, successively. Both Gram‐negative (Escherichia coli and Pseudomonas aeruginosa) and Gram‐positive (Bacillus subtilis and Streptococcus pneumoniae) micro‐organisms were tested against H2L Schiff base ligand and its nano‐sized metal(II) complexes. Candida albicans and Aspergillus fumigatus were tested for antifungal activity, revealing that most complexes had activity lower than H2L ligand, while the complex of Ni(II) exhibited no discernible antifungal activities. Furthermore, the manufactured complexes underwent testing for their in‐vitro anticancer and antibacterial effectiveness. Furthermore, the complexes antioxidant activity was appraised through DPPH and ABTS inhibition tests, revealing distinct scavenging abilities on DPPH radicals. The complexes were ordered according to their scavenging capacity as follows: Ni(II) complex > Pd(II) complex > Pt(II) complex. Finally, the study of cell cycle arrest by the Ni(II), Pd(II), and Pt(II) complexes on HEPG2 has also been performed through flow cell cytometry.

Effect of laser remelting on internal defects and properties of Ni-based coatings reinforced by multi-channel WC in situ

In order to investigate the effect of laser remelting on the properties of hot work die steel, WC reinforced Ni base remelting layer was prepared on H13 steel surface. Optical metallography microscope, X-ray diffractometer and scanning electron microscope were used to analyze the macroscopic defects, phase evolution and microstructure of the coating before and after laser remelting. Microhardness tester and friction and wear tester were used to test the microhardness and wear resistance of the remelted layer, and compared with the coating without remelting. The results show that the inner porosity of the coating decreases with the increase of laser power. With the dissolution of WC/W2C ceramic particles and the uniform distribution of W element, the distribution of reinforcement particles in the coating becomes more and more uniform. When the laser power reaches 1500 W, the WC/W2C ceramic particles inside the coating basically disappear, the porosity is reduced to the lowest, the coating uniformity is the best, and the microhardness and wear resistance are the highest.

An XPS and TEM study of the composition and structure of native oxides on the inner surface of as-received Ni base alloy steam generator tubes

Ni based alloys steam generator (SG) tubes in pressurized water reactors may suffer generalized corrosion and Ni release in primary water. The processes of corrosion and oxidation are strongly dependent on the surface properties. In particular, the chemical composition and structure of the native oxide films present at the surface of the SG tubes are crucial and improving the passive properties of the surface could contribute to reduce the corrosion damage and Ni release. The native oxides on the inner surface of two as-received Ni base alloy SG tubes were investigated using two main techniques, namely X-ray photoemission spectroscopy and transmission electron microscopy. The chemical elements present in the native film for the two tubes were identified and the structure and composition of the native film at the nanoscale was determined. A duplex oxide structure was identified for both samples, but with differences in the chemical composition of the inner and outer oxide layer. Chemical heterogeneities such as alumina, Ti oxides and Cr oxides were also detected; they are considered to play a role in the evolution of the surface exposed to primary water. The two techniques used allowed a multi-scale description of the surface and led to complementary results.

Synthesis, Characterization and Breast Anti-cancer Activity of Iron(II), Cobalt(II), Nickel(II) and Copper(II) Complexes with a Hexadentate Schiff Base Ligand Derived from 2,5-Dihydroxy-1,4-benzoquinone with 5-Amino-2-methylphenol

The complexes of Fe(II), Co(II), Ni(II), and Cu(II) Schiff base ligand derived from 2,5-dihydroxy-1,4-benzoquinone and 5-amino-2-methylphenol were synthesized. The ligand was synthesized by the reaction between the mentioned ketone and amine in 1:2 molar ratio, respectively. The four metal complexes were synthesized by refluxing the ligand with the related metal(II) chloride salts. The synthesized compounds were characterized using FTIR spectroscopy, UV-visible, 1H-NMR, conductivity, atomic absorption, magnetic susceptibility, and thermogravimetric analysis. According to the results, the chelation between metals and ligand occurs with the imine groups and the deprotonated hydroxyl groups of 2,5-dihydroxy-1,4-benzoquinone and 5-amino-2-methylphenol in the ligand. The conductivity test of the four complexes shows the non-electrolytic nature of them. The magnetic susceptibility values of Fe(II), Co(II), Ni(II), and Cu(II) complexes are 4.20, 4.11, 2.97, and 2.34 B.M, respectively. The thermogravimetric and atomic absorption analyses suggest the general chemical formula for the complexes is [M2(L)(H2O)6]. In addition, the ligand and one of its metal complexes (Co(II) complex) were examined against breast cancer cells, and they gave the IC50 of 101.24 and 129.2 µg/mL, respectively. This result suggests that Co(II) complex is a better anti-cancer agent in comparison with the ligand.

High Energy Density Welding of IN792 Ds Superalloy

Ni base superalloys are commonly employed in the industrial fields of aerospace, automotive and energy production due to their excellent mechanical properties and corrosion resistance at high temperature. Superficial defects and cracks may occur during both manufacturing process of components and their service life. High energy density welding techniques, electron beam (EBW) and laser beam (LBW) welding, can be used to create efficient repairs. Joints, obtained by EBW and LBW of IN792 directionally solidified (DS) superalloy, have been investigated to determine the presence of defects, and evaluate the mechanical properties related to specific microstructural features. The results showed that a pre-heating temperature (PHT) higher than 200 °C is always necessary to prevent the formation of hot cracks in the molten zone (MZ) and heat affected zone (HAZ). The process parameters have been optimized to get a good quality of the seams (lack of macro-defects, a good penetration depth and width). Some preliminary test of post-welding heat treatments (PWHTs) have been investigated to homogenize as far as possible the microstructure and the mechanical properties across the seams. The results obtained by the two techniques, EBW and LBW, have been compared and discussed.

Effect of Grain Size on the Heat-Affected Zone (HAZ) Cracking Susceptibility in Ni Base XH67 Superalloy

Effect of Grain Size on the Heat-Affected Zone (HAZ) Cracking Susceptibility in Ni Base XH67 Superalloy

Analysis of the high cracking resistance of a Co Ni superalloy during laser additive manufacturing

A newly developed CoNi-based superalloy is demonstrated to be tolerant of a wide range of laser powder bed fusion print conditions, with limited defect content and high relative densities. These promising traits motivated investigation of the structural uniformity in samples printed at the upper end of the scan velocity processing window (>▪). A new misorientation metric, starting reference orientation deviation (SROD), was calculated from ▪-scale 3D microstructure information to examine structure evolution during epitaxial growth of columnar grains. Misorientations of >20° were observed within the large columnar grains that grew through multiple build layers. The SROD observations highlight the CoNi superalloy's ability to plastically deform to high levels, as evidenced by misorientation gradients, across the range of temperatures experienced in laser additive manufacturing. Misorientation gradients within the columnar grain structure are high relative to Ni base superalloys, allowing for strengthening with high volume fractions of L12 precipitates.

Effect of sintering parameters on phase evolution, microstructural development and mechanical behavior of Ni46Al12Co18Cr8Fe12Mo4 high entropy alloy synthesized via mechanical alloying and spark plasma sintering

The aim of this research work was to study phase evolution, microstructural development and resulting mechanical properties in Ni46Al12Co18Cr8Fe12Mo4, at. % high entropy alloys (HEAs) synthesized via spark plasma sintering (SPS) of 50 hr mechanically alloyed (MAed) powder with varied sintering parameters. Detailed microstructural analysis of the consolidated samples revealed that sintering at 1100 °C resulted in improved densification, i.e. up to 99% and enhanced grain growth compared to the samples sintered at lower temperatures. Phase analysis of the sintered HEAs envisaged formation of face centered cubic (FCC) structured single-phase solid solution with minor amount of brittle sigma (σ) phases. Phase diagram generated from Thermo-Calc shows that volume fraction of the σ phases decreases continuously with temperature and further they dissolve at 1180 °C, which is in close agreement with experimental results of differential thermal analysis (DTA) performed on the sintered samples. Moreover, microhardness of the consolidated HEAs decreased gradually with increase in sintering temperature, ascribed to lower volume fraction of the brittle σ phases at higher temperature. Further, nanoindentation test was conducted to estimate the hardness of the individual phases and it was found that nanohardness of σ phase is approximately 1.7 times higher than that of the solid solution phase. The HEA sintered at 1100 °C showed an excellent strength-ductility synergy, with a compressive yield strength of 1121 ± 21 MPa and the elongation to failure up to 20 ± 1%, attributed to the presence of ductile FCC phase with minor amount of brittle σ phase. The present study demonstrates the potential of SPS technique to synthesize Ni base HEA with excellent thermal stability and superior mechanical properties for structural applications.

The Stress-Controlled Low Cycle Fatigue Properties of HK40 and HP40 Heat-Resistant Fe–Ni Base Alloys

The Stress-Controlled Low Cycle Fatigue Properties of HK40 and HP40 Heat-Resistant Fe–Ni Base Alloys

Diffusion bonding of FGH98 superalloy and DD5 single crystal using pure Ni interlayer

In this study, the FGH98 superalloy and DD5 single crystal were diffusion bonded using pure Ni interlayer under the pressure of 4 MPa. The elemental interdiffusion of Ni interlayer and base materials induced Ni3Al phases (γ’) reinforced Ni-based solid solution (γ) bonding seam (Ni layer zone), achieving the reliable joining of FGH98 and DD5. With the increase of diffusion bonding temperature, the elemental interdiffusion was promoted significantly, which was beneficial to the formation of γ’ phase in the joint. Due to the formation and enlargement of γ’ phase, the hardness of the Ni layer zone and the joint shear strength raised. The high diffusion bonding temperature (1160 ℃) resulted in γ’ phase bulk in the Ni layer zone, and the maximum joint strength of 630 MPa was achieved. However, the fracture of the joint obtained at 1160 ℃ was located in the Ni layer zone.

Development of High-Entropy Alloy (HEA) Anode for Carbon-Free and Electrochemically-Stable Operation of SOFC on Hydrocarbon Fuels

State of the art SOFCs, consisting of Ni base anode, experience excessive localized endothermic cooling and carbon deposition during internal reforming of hydrocarbon fuels. To mitigate the above issues, we developed high-entropy alloy (HEA) anode consisting of optimized mixture of Cu, Ni, Co, Fe and Mn transition metals. Alloys were synthesized using co-precipitation technique and experimentally evaluated for internal reforming and electrochemical activity under SOFC operating conditions. As-synthesized HEA catalysts were also characterized by techniques including N2 adsorption/desorption analysis, SEM, XRD, TPR, TPO and TPD. Compared with standard Ni/YSZ and Ni/GDC anodes, HEA anode containing gadolinium-doped ceria (GDC) showed controlled reforming of methane. Raman spectroscopy and SEM microscopy confirmed the absence of carbon on the HEA/GDC anode.

Crystallographic, antibacterial, and in silico studies of Ni(II) and Cu(II) Schiff base complexes derived from 2-acetylpyridine

Two Schiff base complexes, namely Ni(L1)(NCS)2 (2) and Cu(L1)(NCS).SCN (3) (where L1 = [N,N′-bis(1-(pyridin-2-yl)ethylidene)propane-1,3-diamine]) have been synthesized through condensation of L1 with metal acetates using a 2:1 ratio, in the presence of sodium thiocyanate, NaSCN. The complexes were characterized by elemental analysis, IR, UV–Vis, magnetic moment, as well as molar conductivity. The crystal structures of complexes 2 and 3 were successfully characterized by single crystal X-ray crystallography. The Ni atom in 2 is in a distorted octahedral environment while the Cu atom in 3 is in an environment lying between square pyramidal and trigonal bipyramidal; in both complexes the NCS− is acting as terminal ligand. Both complexes were paramagnetic. Density functional theory (DFT) calculations were performed at the B3LYP/LanL2DZ level of theory to explore the quantum chemical properties of the ligand and its metal complexes. The calculations proceed with the 3D crystal structure characterization of the complexes, and the correlation between theoretical and experimental results were discussed. NBO analysis was used to determine the strength of donor–acceptor interactions in metal complexes. The antibacterial activity of the synthesized compounds was screened in vitro against two strains of Gram-positive (Staphylococcus (S.) aureus, Staphylococcus (S.) haemolyticus) and three strains of Gram-negative (Shigella (S.) sonnei, Salmonella (S.) typhimurium, Enterobacter (E.) aerogenes) bacteria, and showed no activity. The binding affinity of the synthesized complexes in the binding site of S. aureus tyrosyl-tRNA was investigated using molecular docking, and the outcomes showed a good agreement with experimental results.

Bifunctional Lewis acid-base nanocatalysts with dual active sites for strengthened coupling of alcohol conversion and H2 evolution

The synergistic of organic transformation with H2 production in one redox cycle is highly desirable to achieve the full use of photogenerated holes and electrons but challenging. Herein, Lewis acid-base nanocatalysts in which Ni decorated defective ZnIn2S4 (denoted as Ni/VZIS) has been prepared through photodeposition with Zn defective ZnIn2S4 nanosheets as precursor. The Zn vacancies favors the selective deposition of Ni, enabling the co-exposure of Lewis acid Ni and Lewis base S adjacent dual active sites. In-situ FTIR results reveal the coexistence of Ni and Zn vacancy on ZnIn2S4 favored the chemisorption of benzyl alcohol. The electron-deficient Ni Lewis acid (LA) site and electron-rich S Lewis base (LB) site can act as benzyl alcohol conversion and H2 evolution sites, respectively, thus facilitating the full use of photoinduced electrons and holes. The spectroscopy and photoelectrochemical studies demonstrate the transfer and separation of photogenerated carries are also facilitated in the nanohybrids. As such, the Ni/VZIS photocatalyst show outstanding performance of photocatalytic conversion benzyl alcohol (BA) into benzaldehyde (BAD) and H2, with the optimal H2 generation rate of 81.9 μmol h−1, accompanying benzaldehyde generation rate of 73.7 μmol h−1. This work provides a profound insight into the designing of multi-functionalized nanohybrids for the full use of photoexcited electrons-holes pairs.

Making a coherent L12-nano-precipitates-reinforced Ni-based alloy ultrastrong and ductile by constructing dual heterogeneous structures

It is known that inhibiting rapid decline of strain hardening is crucial in enhancing uniform ductility under uniaxial tension stress for metallic materials with high yield stress. In this study, a high-mechanical-response Ni-based alloy was introduced by fabricating a dual-heterogeneous structure allowing to provide improved strain-hardening capability at both ambient and cryogenic temperatures. Especially at cryogenic temperature, an exceptional strength-ductility synergy with yield strength of 1.85 GPa and ductility of 24% can be achieved, accompanied by a distinctive five-stage strain-hardening response. In such a case, deformation twinning behavior was activated successfully to assist the strain hardening in the Ni base alloy although precipitation-hardening effect was available. Our work sheds light on the strain hardening effect assisted by twinning previously unexpected in coherent precipitation-hardened Ni base alloys, and hence represents a promising route for improving uniform ductility of Ni base alloys with high yield strength.

Gamma ray irradiated binuclear and mononuclear transition metal complexes with polydentate ligand: Template synthesis, spectral, XRD, morphology, solid electrical conductivity and antimicrobial activity

In this work, new binuclear Fe(III), Ni(II) and mononuclear Cu(II) Schiff base complexes that obtained via template condensation of Fe(III), Ni(II) and Cu(II) chlorides with N1-(3-aminopropyl) propane-1,3-diamine and 1,3-diphenylpropane-1,3‑dione (1B, 2B, 3B), respectively were prepared and well investigated. The structure of the complexes was elucidated by means of microanalyses, various spectroscopic techniques (FT–IR, UV/Vis, X–ray diffraction), thermal (TG/DTG), molar conductivity and magnetic moment measurements, Fe(III), Ni(II) complexes have an octahedral structure, while Cu(II) complex adopts distorted square pyramidal geometry. To study γ– irradiation induced modifications, powder sample of these complexes was exposed to high energetic γ–ray irradiation at a dose of 20 kGy, (hereafter referred to as 1A, 2A, 3A, respectively). Physico-chemical properties of irradiated samples were also investigated by the aforementioned tools. The results revealed no remarkable change in the molar conductivity values and little shift of the peak position and the intensity for FT–IR and electronic spectra as a result of the distortion of lattice planes. Also, TG/DTG studies revealed decreasing in the thermal stability for all irradiated samples. From the powder XRD data for non-irradiated and γ–irradiated Ni(II) (2B, 2A) and Cu(II) (3B, 3A) complexes, average crystallite size (D) and dislocation density (δ) were calculated, the γ–irradiation resulted in decrease in the crystallite size for Ni(II) (2A) complex. The irradiated (3A) showed changes in the surface morphology compared to its non-irradiated one. The solid state electrical conductivity of non-irradiated and γ–irradiated Ni(II) complexes have been investigated. Furthermore, the non-irradiated samples (1B, 3B) and their γ–irradiated (1A, 3A) were assayed for their antibacterial property against Gram–positive as Staphylococcus aureus, Gram– negative as Escherichia coli and antifungal property against fungi as Candida albicans.

Synthesis, Characterization, Powder X-Ray Diffraction Analysis, ESR Study, Thermal Stability of Ni(II) and Fe(III) Schiff Base Ligand Complexes and Potency Study as Antibacterial and Antioxidant Agents

The salen-type Ni(II) and Fe(III) complexes were successfully syntheses by using Schiff base ligand [E]-2,2'-((pentane-1,3-diylbis(azanylylidene))bis(ethan-1-yl-1-ylidene))bis(naphthalen-1-ol) (L1) and its derivatives (L2) and (L3). Due to their chelating properties and ability to coordinate with a wide range of transition metal ions of different oxidation states, they are considered an important family of organic compounds. The structure of the metal complexes was elucidated by different spectral techniques (FT-IR, 1H NMR, mass spectrometry, UV–visible, powder X-ray diffraction, DGA-TGA, and ESR). The powder X-ray diffraction data revealed that Ni(II) complexes are arranged in a triclinic system while Fe(III) complexes are in a monoclinic system with space group P1. TGA-DTA study suggests that the Ni(II) ion does coordinate with the N2O2 Schiff base ligands with coordination number 4. Also, the Fe(III) ion does coordinate with the N2O2 Schiff base ligands with coordination number 6. The Ni(II) complex exhibits the square planar geometry with unpaired electron lying in the dx2-y2 orbital. The EPR spectra of Fe(III) complexes may suggest an octahedral structure around the Fe(III) ion. The antibacterial activity was tested against different pathogens and confirmed that the presence of the –I and –NO2 group with N2O2 donor Schiff bases ligand are responsible for strongly inhibiting bacterial growth of metal complexes. The Ni(II) complexes showed higher potency antioxidant activity, indicating that the Ni (II) complexes exhibited more prominent antioxidant activity than the Fe (III) complexes.

New Ni(II) and Cu(II) Schiff base coordination complexes derived from 5-Bromo-salicylaldehyde and 3-picoyl amine/ethylenediamine: Synthesis, structure, Hirshfeld surface and molecular docking study with SARS-CoV-2 7EFP-main protease

Two co-ordination compounds, one nickel(II) complex [Ni(L1)(Phen)2]ClO4(1) and one copper(II) complex [Cu(L2)] (2), were synthesized using Schiff base ligands derived from the condensation reaction of 5-Bromo-salicylaldehyde with 3-picoyl amine (L1H)(L1H = (E)-4-Bromo-2-(((pyridin-3-ylmethylene)amino) methyl) phenol) and ethylenediamine (L2H2), respectively(L2H2 = 2,2′-((1E,1′E)-(ethane-1,2-diylbis(azaneylylidene))bis(methanelylidene))bis (4-bromophenol)). The newly synthesized complexes were fully characterized, including X-ray crystallography. The crystal structure of both the complexes was determined using Single Crystal structure analysis. The electrochemical properties of (1) were studied using cyclic voltammetry. DFT calculations were done for the newly synthesized co-ordination complexes to have a relevant and reasonably accurate calculation of their molecular and electronic behavior. The Hirshfeld surface (HS) analysis was also performed using the crystallographic data for investigating the nature and quantitative contribution of all possible non-covalent intermolecular interactions within the crystal lattice. To explore potential SARS-CoV-2 drug candidates, both the co-ordination compounds were subjected to molecular docking calculations with the SARS-CoV-2 virus (PDB ID: 7EFP). The molecular docking calculations of Ni(II) complex (1) into the 7EFP-main protease of SARS-CoV-2 virus revealed the binding energy of −11.5 kcal/mol, while Cu(II) complex (2) exhibited the binding energy of −8.5 kcal/mol at the inhibition binding site of the receptor protein.