Synthesis, structural and corrosion inhibition studies on Mn(II), Cu(II) and Zn(II) complexes with a Schiff base derived from 2-hydroxypropiophenone

Bishydrazone ligand and its Zn-complex: synthesis, characterization and estimation of scalability inhibition mitigation effectiveness for API 5L X70 carbon steel in 3.5% NaCl solutions

Bishydrazone ligand, 2,2'-thiobis(N'-((E)-thiophen-2-ylmethylene) acetohydrazide), H2TTAH and its Zn- complex were prepared and characterized through elemental analysis and various spectroscopic performances as well as (IR, 1H and 13C NMR, mass and (UV-Vis) measurements. The synthesized complex exhibited the molecular formula [Zn2(H2TTAH)(OH)4(C5H5N)3C2H5OH] (Zn-H2TTAH). To assess their potential as anti-corrosion materials, the synthesized particles were assessed for their effectiveness for API 5L X70 C-steel corrosion in a 3.5% NaCl solution using electrochemical methods such as potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS). Additionally, X-ray photoelectron spectroscopy (XPS) was employed to examine the steel surface treated with the tested inhibitors, confirming the establishment of an adsorbed protecting layer. The results obtained from the PP plots indicated that both H2TTAH and Zn-H2TTAH act as mixed-type inhibitors. At a maximum concentration of 1 × 10-4 M, H2TTAH and Zn-H2TTAH exhibited inhibition efficiencies of 93.4% and 96.1%, respectively. The adsorption of these inhibitors on the steel surface followed the Langmuir adsorption isotherm, and it was determined to be chemisorption. DFT calculations were achieved to regulate the electron donation ability of H2TTAH and Zn-H2TTAH molecules. Additionally, Monte Carlo (MC) simulations were conducted to validate the adsorption configurations on the steel surface and gain insight into the corrosion inhibition mechanism facilitated by these molecules.

Synthesis, characterization, molecular docking, and antimicrobial activities of dinuclear nickel(ii), palladium(ii), and platinum(iv) complexes

New nickel(ii), palladium(ii), and platinum(iv) complexes were synthesized by reacting the metal ions with benzidinedioxime in a 1 : 1 mole ratio. The CHN elemental analysis, spectroscopic analyses, and powder X-ray diffraction (PXRD) results showed that two Ni(ii) and two Pd(ii) ions coordinated to two benzidinedioxime ligands via the nitrogen atoms of both oxime groups and the two azomethine nitrogen atoms. In the case of the dinuclear platinum(iv) complex, however, each Pt(iv) is coordinated with the two oxygen atoms of the oxime group and the two azomethine nitrogen atoms of the ligand. Both elemental analyses and PXRD indicated that the complex ions of Ni(ii) and Pt(iv) have distorted octahedral geometry, whereas Pd(ii) has a square planar geometry. Molecular docking studies showed that the nickel(ii) complex is the most potent dual DHPS/DHFR bacterial inhibitor. The receptor of the DHPS enzyme (3ZTE) showed the best interaction with the nickel(ii) complex when compared to a receptor of the DHFR enzyme (3FRB). All the synthesized complexes and ligand exhibited significant results against PS. Aeruginous than their corresponding SMX-TMP drug. Among the three synthesized complexes, the nickel(ii) complex possessed the highest antimicrobial activities against tested microorganisms.

Synthesis, spectral characterization, computational studies, antifungal, DNA interaction, antioxidant and fluorescence property of novel Schiff base ligand and its metal chelates

Cobalt, Copper, Nickel and Zinc coordinated metal complexes were synthesized by novel thiazole Schiff base ligand 2-ethoxy-4-((5-methylthiazol-2-ylimino)methyl) phenol derived from 3-ethoxy-4-hydroxybenzaldehyde and 2-amino- 5-methylthiazol. The synthesized compounds were spectrochemically characterized by elemental analysis, molar conductance, FT-IR, UV-Vis, Mass spectral analysis, Powdered-XRD and cyclic voltammetry. The thermal stability of synthesized complexes were investigated by using thermogravimetric analysis (TGA). Theoretical computational study were performed for all the synthesized compounds utilizing the DFT/B3LYP method at the 6-31G basic set for Schiff base ligand whereas LANL2DZ basis set for metal complexes. Molecular Electrostatic Potential (MEP), HOMO-LUMO, Mulliken charges and global reactivity descriptors, including chemical potential (μ), global softness (S), chemical hardness (η), and electrophilicity index (ω) were measured and correlated with antimicrobial activity. The synthesized thiazole Schiff base ligand and its coordinated metal complexes shows good antifungal agreement against Fusarium Oxysporum and Aspergillus Niger species. These compounds also exhibit DNA binding, DNA cleaving and antioxidant activity. All the synthesized molecules indicate potential fluorescence property.

Innovation of Imine Metal Chelates as Corrosion Inhibitors at Different Media: A Collective Study

The corrosion inhibition of transition metal chelates derived from Schiff base ligands was tested for (mild, copper, stainless, aluminum and carbon) steel in various concentrations of (HCl, HNO₃ and H₂SO₄) acidic medium at 25 °C through (weight loss, potentiodynamic polarization, polarization curves, electrochemical impedance spectroscopy (EIS) and open circuit potential measurements (OCP)) techniques. The studied compounds were identified with various spectral, analytical and physico-chemical techniques. It was observed that the investigated compounds had a significant inhibitory impact on the corrosion of diverse steels in the medium investigated. The analysis shows that increasing the dose of the studied complexes improves the corresponding inhibitory efficiency values. Negative results of Gibb’s free adsorption energy (ΔGads0) prove the suppression process’s spontaneous and physical adsorption, which contradicts the Langmuir adsorption isotherm. As a result of this insight, a novel bridge between nuclearity driven coordinated inorganic chemistry and materials, as well as corrosion control, has been built. This review provides an overview of the use of Schiff bases and associated transition metals as potential corrosion inhibitors, including the factors that influence their application.

Effective corrosion inhibition of mild steel in hydrochloric acid by newly synthesized Schiff base nano Co(ii) and Cr(iii) complexes: spectral, thermal, electrochemical and DFT (FMO, NBO) studies

Two new cobalt(ii) and chromium(iii) complexes were synthesized and characterized by FT-IR, ¹HNMR, UV, elemental analysis, TGA, conductivity, XRD, SEM, and magnetic susceptibility measurements. Structural analysis revealed a bi-dentate chelation and octahedral geometry for the synthesized complexes. The optical band gap of the Co(ii)-L and Cr(iii)-L complexes was found to be 3.00 and 3.25 eV, respectively revealing semiconducting properties. The X-ray diffraction patterns showed nano-crystalline particles for the obtained complexes. In addition, the synthesized metal complexes were examined as corrosion inhibitors for mild steel in HCl solution. The electrochemical investigations showed a maximum inhibition efficiency of 96.60% for Co(ii)-L and 95.45% for Cr(iii)-L where both complexes acted as mixed-type inhibitors. Frontier Molecular orbital (FMO) and Natural bond orbital (NBO) computations showed good tendency of the ligand to donate electrons to the metal through nitrogen atoms while the resultant complexes tended to donate electrons to mild steel more effectively through oxygen atoms and phenyl groups. A comparison between experimental and theoretical findings was considered through the discussion.

Two Co(ii) and Cr(iii) complexes were synthesized, characterized and examined as corrosion inhibitors. The electrochemical data showed high inhibition efficiencies with mixed-type behavior. FMO and NBO were considered for the computational analysis.

Inhibitory Potential of New Phenolic Hydrazide-Hydrazones with a Decoy Substrate Fragment towards Laccase from a Phytopathogenic Fungus: SAR and Molecular Docking Studies

Laccase from pathogenic fungi participates in both the delignification and neutralization of phytoantibiotics. Furthermore, it interferes with the hormone signaling in plants and catalyzes melanization. Infections of these pathogens contribute to loss in forestry, agriculture, and horticulture. As there is still a need to expand knowledge on efficient defense strategies against phytopathogenic fungi, the present study aimed to reveal more information on the molecular mechanisms of laccase inhibition with natural and natural-like carboxylic acid semi-synthetic derivatives. A set of hydrazide-hydrazones derived from carboxylic acids, generally including electron-rich arene units that serve as a decoy substrate, was synthesized and tested with laccase from Trametes versicolor. The classic synthesis of the title inhibitors proceeded with good to almost quantitative yield. Ninety percent of the tested molecules were active in the range of K_I = 8–233 µM and showed different types of action. Such magnitude of inhibition constants qualified the hydrazide-hydrazones as strong laccase inhibitors. Molecular docking studies supporting the experimental data explained the selected derivatives’ interactions with the enzyme. The results are promising in developing new potential antifungal agents mitigating the damage scale in the plant cultivation, gardening, and horticulture sectors.

A Review of Recent Advances in the Inhibition of Sweet Corrosion

This review paper discusses the research work published in the last decade on the use of organic compounds and natural products as corrosion inhibitors for steel in CO₂ and CO₂ /H₂ S coexisting environments. The carbon and mild steel samples tested are mostly immersed in CO₂ -saturated NaCl/brine solutions or simulated oilfield waters. The influence of temperature, immersion time, CO₂ partial pressure, pre-corrosion, flow rate/rotation speed, and the synergistic effect of other compounds on the corrosion inhibition effectiveness of organic compounds and natural products is presented. Primarily, weight loss and electrochemical techniques were used to evaluate the corrosion inhibition effectiveness of these compounds.

The crystal structure of bis(N-(amino(pyridin-2-yl)methylene)-5-chloro-2-hydroxybenzohydrazonato-κ3 N,N′,O)zinc(II) – methanol (2/5), C57H60Cl2N16O13Zn2

C57H60Cl2N16O13Zn2, monoclinic, P21 (no. 4), a = 11.0273(2) Å, b = 22.1495(3) Å, c = 13.3766(2) Å, β = 107.000(1)°, V = 3124.46(9) Å3, Z = 2, R gt(F) = 0.0316, wR ref(F 2) = 0.0806, T = 296(2) K [1–3].

The crystal structure of (5-chloro-2-hydroxy-N-(4-methoxy-2-oxidobenzylidene)benzohydrazonato-κ3 N,O,O′)-(pyridine-κ1N)copper(II), C20H16ClCuN3O4

C20H16ClCuN3O4, triclinic, P1̄ (no. 2), a = 7.629(4) Å, b = 8.893(5) Å, c = 14.193(8) Å, α = 88.603(6)°, β = 81.093(6)°, γ = 83.715(6)°, V = 945.6(9) Å3, Z = 2, R gt(F) = 0.0245, wR ref(F 2) = 0.0709, T = 296(2) K.

2-Hydroxy-N'-((Thiophene-2-yl)methylene)benzohydrazide: Ultrasound-Assisted Synthesis and Corrosion Inhibition Study

2-Hydroxy-N'-((thiophene-2-yl)methylene)benzohydrazide (HTMBH) was synthesized by conventional method as well as by ultrasonication (US). The ultrasound-assisted synthesis of HTMBH was found to have good yield and be more eco-friendly compared to the conventional method of synthesis. The synthesized compound HTMBH was characterized by Fourier transform infrared, 1H NMR, and CHN analyses. The corrosion inhibition behavior of HTMBH was investigated using gravimetric and electrochemical methods in 0.5 M H2SO4. The thermodynamic adsorption parameters revealed that HTMBH was adsorbed on the mild steel surface in both ways, physically and chemically, although physisorption is predominant. The study of activation parameters revealed that it is the increase in activation energy that is a prominent factor to lower the corrosion rate in acid medium. Atomic force microscopy analysis is also carried out to investigate the effect of HTMBH on the surface of mild steel surface in acid solution. The contact angle measurement showed decreased affinity of mild steel surface for acid solution containing HTMBH. The results obtained from all of these methods showed good consistency.

Green synthesis and corrosion inhibition study of 2-amino-N′-((thiophen-2-yl)methylene)benzohydrazide

2-Amino-N′-((thiophen-2-yl)methylene)benzohydrazide (ATMBH) was synthesized by a conventional method, as well as by microwave (MW) irradiation.

A selective naked-eye chemosensor derived from 2-methoxybenzylamine and 2,3-dihydroxybenzaldehyde - synthesis, spectral characterization and electrochemistry of its bis-bidentates Schiff bases metal complexes

A new colorimetric receptor HL, acting as a bidentate Schiff base ligand, has been synthesized by condensation of 2-methoxybenzylamine on 2,3-dihydroxybenzaldehyde in a methanolic solution. Interestingly, this chelating agent can selectively detect Cu²⁺, Co²⁺, Fe²⁺ and Fe³⁺ ions with a simple and an easy-to-make, well defined naked-eye visible color changes in two different solvents like acetonitrile and methanol. This bidentate ligand coordinates three metal ions of Co(II), Cu(II) and Fe(II) via nitrogen and oxygen atoms. The molecular structures of the synthesized compounds were elucidated by various physicochemical properties such as the elemental analysis, FT-IR, HNMR, UV-Vis and the Mass spectrometry. The resulting general formulae [M(L)₂·H₂O] (M(II)=Cu, Fe, Co) are proposed as mononuclear complexes. The solvatochromism properties of these compounds were studied with their absorption spectra using different solvents as methanol (MeOH), acetonitrile (AN), tetrahydrofuran (THF), dimethylformamid (DMF), dimethylsulfoxid (DMSO) and dichloromethane (DC). The Electrochemical behavior of copper complex was explored in DMF solutions by cyclic voltammetry (CV) with two working electrodes: glassy carbon (GC) and platinum electrode (Pt). This study reveals that copper complex shows successively two redox systems as Cu^III/II and Cu^II/I. The Fe^III/II and Co^II/I redox systems have also been studied in DMF and DMSO media.

A Novel Schiff Base of 3-acetyl-4-hydroxy-6-methyl-(2H)pyran-2-one and 2,2'-(ethylenedioxy)diethylamine as Potential Corrosion Inhibitor for Mild Steel in Acidic Medium

The corrosion inhibition activity of a newly synthesized Schiff base (SB) from 3-acetyl-4-hydroxy-6-methyl-(2H)-pyran-2-one and 2,2'-(ethylenedioxy)diethylamine was investigated on the corrosion of mild steel in 1 M HCl solution using potentiodynamic polarization and electrochemical impedance spectroscopic techniques. Ultraviolet-visible (UV-vis) and Raman spectroscopic techniques were used to study the chemical interactions between SB and mild steel surface. SB was found to be a relatively good inhibitor of mild steel corrosion in 1 M HCl. The inhibition efficiency increases with increase in concentration of SB. The inhibition activity of SB was ascribed to its adsorption onto mild steel surface, through physisorption and chemisorption, and described by the Langmuir adsorption model. Quantum chemical calculations indicated the presence of atomic sites with potential nucleophilic and electrophilic characteristics with which SB can establish electronic interactions with the charged mild steel surface.