Mixed-type Inhibitor Research Articles

Electrochemical and DFT insights into 2-amino-4-(4-hydroxy-3-methoxyphenyl)-7-methyl-4H-chromene-3-carbonitrile: an innovative strategy for antibacterial activity and corrosion protection of carbon steel.

This study explored the potential of a newly synthesized derivative, 2-amino-4-(4-hydroxy-3-methoxyphenyl)-7-methyl-4H-chromene-3-carbonitrile (AHMCC), as a broad-spectrum antibacterial agent and a corrosion inhibitor for carbon steel (C.STL) in 0.5 M HCl solution. AHMCC demonstrated remarkable antibacterial efficacy against Gram-negative (Escherichia coli, Klebsiella pneumoniae) and Gram-positive (Bacillus subtilis, Staphylococcus aureus) bacteria, as evidenced by agar plate tests and cell viability assays. In the corrosion inhibition studies, AHMCC exhibited mixed-type inhibitor behavior as revealed by potentiodynamic polarization (PDP) measurements. The inhibition efficiency increased with rising AHMCC concentration, confirmed by a significant enhancement in charge transfer resistance (R ct) observed in electrochemical impedance spectroscopy (EIS) analysis. Electrochemical frequency modulation (EFM) data with obtained CF2 and CF3 values further corroborated these findings. Langmuir isotherm modeling suggested AHMCC molecules followed a monolayer adsorption pattern on the C.STL surface. UV-visible spectroscopy indicated the formation of a protective layer through chemical interaction between AHMCC and the metal surface. Atomic force microscopy (AFM) provided visual confirmation of this protective film shielding the C.STL from the corrosive environment. Additionally, theoretical calculations supported the proposed adsorption mechanism of AHMCC molecules onto the C.STL surface.

Corrosion inhibition ability of L-tryptophan and 5-hydroxy-L-tryptophan for mild steel: a combination of experimental and theoretical methods.

An investigation into the corrosion inhibition properties of L-tryptophan (TP) and 5-hydroxy-L-tryptophan (5-OH-TP) for mild steel in a 1.0 M HCl acidic medium was conducted using experimental and theoretical methods. Results obtained from polarization curve measurements reveal that TP and 5-OH-TP are effective mixed-type inhibitors, exhibiting the highest inhibition efficiencies of 91.22% and 94.05%, respectively, at a temperature of 293 K and a concentration of 10-2 M. However, their inhibition efficiencies gradually decline with increasing temperature, reaching the lowest values of 70.65% for TP and 73.55% for 5-OH-TP at a concentration of 10-4 M and a temperature of 323 K. The adsorption of TP and 5-OH-TP on the steel surface follows the Langmuir isotherm, suggesting monolayer adsorption. Electrochemical impedance spectroscopy analysis indicates that the adsorbed inhibitors form a protective film, effectively shielding the steel from corrosive agents in the solution. Notably, 5-OH-TP consistently exhibits superior inhibition efficiency compared to TP, attributed to the presence of polar OH groups that facilitate stronger bonding of the inhibitor molecule with the metal surface. Quantum chemical parameters and molecular dynamics simulations further confirm the superior corrosion inhibition ability of 5-OH-TP over TP in acidic environments. In particular, the binding energies of protonated TP at the N3 position and 5-OH-TP at the N4 position are 556.40 and 579.27 kJ mol-1, respectively.

A combination of experimental and theoretical methods in evaluating triazole derivatives' mild steel corrosion inhibition ability in an acidic solution.

A comprehensive study was conducted, both experimentally and theoretically, to evaluate the corrosion inhibition ability of 4-amino-5-phenyl-4H-1,2,4-triazole-3-thiol (AT) and 4-amino-5-(pyridine-4-yl)-4H-1,2,4-triazole-3-thiol (AP) on mild steel. The findings show that AT and AP are potential mixed-type inhibitors in hydrochloric acid solution. At 293 K and a concentration of 5 × 10-3 M, AT and AP have efficiencies of 93.33% and 97.33%. When the temperature rises to 323 K, their efficiencies drop to 87.27% and 90.82%. The adsorption behavior of AT and AP on the steel surface conforms to the Langmuir adsorption isotherm. A key finding is the superior inhibition performance of AP over AT, attributed to its higher nitrogen heteroatom content, which enhances the interaction with the mild steel surface. Molecular dynamics simulations and quantum chemical calculations reveal that AP exhibits a notably higher binding energy (pAP-N20: 847.17 kJ mol-1) compared to AT (pAT-S18: 847.17 kJ mol-1). This study established a correlation between molecular structure, adsorption behavior, and corrosion inhibition efficiency, providing new insights into the design of effective corrosion inhibitors for industrial applications.

The inhibition effect of 1, 3-diazole glyoxaline on corrosion of API 5L X52 pipeline steel in oilfield produced water under sweet corrosive conditions

Corrosion induced by aqueous environments containing carbon dioxide (CO2) is a well-documented issue in the oil and gas industries, particularly affecting transportation via steel pipelines. Operational conditions during transportation, including temperature, flow rate, and solution chemistry, significantly influence the corrosion inhibition mechanism. In this study, the corrosion inhibition behavior of API 5L X52 steel in a 3.5 wt% NaCl brine solution saturated with carbon dioxide was investigated using 1, 3-diazole glyoxaline (DG) as an organic inhibitor. Both gravimetric and electrochemical methods were employed to assess corrosion rates and inhibitor efficiency across various temperatures, inhibitor concentrations, and rotational speeds. The outcomes showed that inhibition efficiency increased with inhibitor concentration and temperature. From weight loss measurements, the maximum inhibition efficiency was 98.58 % at 3 × 10−4 M of DG and 60 °C. The polarization investigations showed a reduction in the anodic and cathodic curves in the presence of the inhibitor. This suggested a mixed-type inhibition mechanism. The electrochemical impedance spectroscopy results showed an improvement in charge transfer resistance due to the formation of a protective layer on the metal surface. In addition, AFM, SEM, contact angle, hardness, and roughness measurements proved the enhancement in surface morphology due to the presence of DG.

Mannich reaction mediated derivatization of chromones and their biological evaluations as putative multipotent ligands for the treatment of Alzheimer's disease.

Alzheimer's disease (AD) is a complex neurological disorder and multiple pathways are associated with its pathology. Currently available single-targeting drugs are found to be ineffective for the treatment of AD, and most of these drugs provide symptomatic relief. The multi-target directed ligand strategy is proposed as an effective approach for the treatment of AD. Herein, we report the design and synthesis of a series of 2-phenyl substituted chromone derivatives and their evaluation against AChE, MAO-B, and β amyloid self-aggregation inhibition. In the series, NS-4 and NS-13 were identified as the potent leads against all the specified targets. NS-4 and NS-13 exhibited balanced multipotent activities against AChE with IC50 values of 3.09 μM, and 0.625 μM and against MAO-B with IC50 values of 19.64 μM and 12.31 μM, respectively. These compounds also displayed 28.5% and 32.2% self-aggregation inhibition potential against Aβ1-42, respectively. All the compounds were found to be selective for AChE over BuChE. Additionally, NS-4 also exhibited potent BuChE inhibition with an IC50 value of 1.95 μM. Moreover, NS-4 and NS-13 reduced intracellular ROS levels up to 65% against SH-SY5Y cells at 25 μM concentration. The lead compounds were found to be neuroprotective and exhibited no cytotoxicity even at 25 μM concentration. In enzyme kinetic inhibition studies, these compounds showed mixed-type inhibition to AChE. In the computational studies, binding interactions, and orientations of the ligands at the active site of the enzymes were analyzed and these lead compounds were found to be thermodynamically stable inside the active cavity for up to 100 ns.

Synthesis of 5-benzyl-5-((5-nitropyridin-3yl)methyl)-1,3,5-dithiazinan-5-ium through one-pot reactions, characterization and study as a corrosion retardant in high salinity oil fields.

This study included the preparation of a new heterocyclic compound namely 5-benzyl-5-((5-nitropyridin-3-yl) methyl)-1,3,5-dithiazinan-5-ium (BNPD) by a simple powerful method and an environmentally acceptable. The BNPD compound contains O, N, and S heteroatoms that have been inserted into the chemical structure by one step consisting of several transformations. The BNPD structure has been characterized using several techniques like FT-IR, 1H-NMR, 13C-NMR, and G-C mass. The prepared molecule has been studied as an inhibitor of carbon steel corrosion (N-80), which is generally used in oil fields. The BNPD effectiveness has been studied as an anti-corrosive material in saline water that accompanies the extraction of crude oil. Saline water contains dissolved solids estimated at 239581mg/l, conductivity 254.23 ms/cm, and pH 6.1. The retardant has been evaluated by electrochemical impedance spectroscopy technique (EIS), potentiodynamic polarization technique (PP), scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM/EDX), and weight loss method (WL) at 308K(±1). It was noted that inhibition efficiency increases with increasing BNPD concentration. The results of potentiodynamic polarization showed that the studied inhibitor molecules act as a mixed-type inhibitor, while the results of weight loss showed that these molecules adsorbed on the carbon steel surface through physical and chemical adsorption simultaneously. The results of the SEM/EDX indicated that slight corrosion occurred at the inhibitor was added, where the EDX spectrum of N-80 at 80 mg.dm-3 of inhibitor was noticed approximately similar to the polished carbon steel spectrum. Furthermore, the electronic and physic-chemical characteristics of BNPD have been calculated like EHOMO, ELUMO, energy gap, total energy, lipophilicity coefficient, molecule surface area, molecular volume, molecular polarizability, molar refractivity, dipole moment, solvation energy, theoretical inhibition efficiency, and electrostatic potential surfaces. The BNPD compound has shown wonderful results in corrosion inhibiting, where its efficiency optimum reached 91.14%, 93.60%, and 93.46% for WL, EIS, and PP techniques, respectively. Either theoretical efficiency reached 90.25%.

Rhodanine-based 4-(furan-2-yl)benzoic acids as inhibitors of xanthine oxidase

A series of rhodanine derivatives bearing 4-(furan-2-yl)benzoic acid moiety were synthesized and studied as inhibitors of xanthine oxidase. This enzyme is a known target for allopurinol and febuxostat used in the treatment of hyperuricemia, gout, and other diseases. The synthesized compounds with different substituents in position 3 of the rhodanine ring showed in vitro inhibitory activities towards xanthine oxidase in a low micromolar concentration range. The 4-(furan-2-yl)benzoic acid derivative with a fragment of N-unsubstituted rhodanine was found to have the lowest IC50 value which does not depend on the presence of albumin or Tween-80 under the assay conditions. According to kinetic data, the rhodanine-based 4-(furan-2-yl)benzoic acid was a mixed-type inhibitor with the same affinity for the free enzyme and the enzyme-substrate complex. Molecular docking and molecular dynamic studies were performed to elucidate the binding mode of this compound in the active site of xanthine oxidase

A comparison of the corrosion inhibition on 1060 aluminum in HCl solution between water and alcoholic extracts of Mikania micrantha

A detailed comparison of the corrosion inhibitory effect of water extract of Mikania micrantha (MME (H2O)) and 40% ethanol extract (MME (40% C2H5OH)) was conducted on 1060 aluminum in 1.0 M HCl by gravimetric, electrochemical and surface analysis techniques. The results show that two extracts have excellent inhibition performance, MME (H2O) (97.0%) surpasses MME (40% C2H5OH) (93.6%) in terms of maximum inhibition efficiency. MME (H2O) is a mixed-type inhibitor, whereas MME (40% C2H5OH) is mainly a cathodic inhibitor. Salicylic acid, isochlorogenic acid C, sucrose, succinic acid, valine and guanine in MME contribute on the inhibitive action.

Synergistic effect of metal cation and 1-dimethylamino-2-propanol on copper corrosion protection in alkaline solution

BackgroundCopper (Cu) has versatile applications in microelectronic industry and its corrosion protection in the manufacturing process is an important reliability issue. MethodsIn this study, mixed type corrosion inhibitor is formulated by complexation of metal cation (Ni2+) and tertiary amine (1-dimethylamino-2-propanol), and its synergistic effect on the corrosion protection of Cu in alkaline solution is systematically investigated. Electrochemical, microstructural, and chemical state analyses of the Cu surfaces with and without the inhibitor protection are performed to realize the protection efficacy of the mixed type inhibitor against corrosion. Significant findingsThe results show that the polarization resistance of the Cu surface is increased with the introduction of mixed type inhibitor (Ni2+-1-dimethylamino-2-propanol), achieving a higher inhibition efficiency of 48 % compared to the cation-free inhibitor (1-dimethylamino-2-propanol) of 25 %. The higher inhibition efficiency is attributed to the stronger adsorption capability of mixed type inhibitor on the Cu surface as confirmed by the X-ray photoelectron spectroscopy analysis and quantum chemical calculations.

A sustainable approach exploiting Chrysanthemum Coronarium flowers distillation waste as a corrosion suppressor for low carbon steel in monoprotic acid medium through electrochemical and computational evaluations

This study focuses on evaluating a biowaste generated amid the hydrodistillation process of Chrysanthemum Coronarium Flower compounds as a sustainable inhibitor for the corrosion of carbon steel in the hydrochloric medium. Total phenolic and flavonoid contents, phytochemical screening protocols as well as Fourier Transform Infrared (FT-IR) analysis were implemented to examine the phytochemical diversity of the Chrysanthemum Coronarium flowers extract (CCFE). Electrochemical impedance spectroscopy (EIS) as well as Tafel extrapolation techniques were adopted for examining the corrosion suppression efficiency of the liquid waste as a corrosion inhibitor at 293 K. The findings indicated that the CCFE displayed strong corrosion suppression properties on the metal, achieving an impressive efficiency of 82 %. Following a mixed-type inhibition mechanism. Temperature influence in the presence of the CCFE was assessed at a 293–313 K domain, and the combined impact of KI and the CCFE inhibitor was investigated to determine their synergistic effects. Furthermore, an in-depth analysis of the surface morphology of metal was carried out using SEM-EDX analysis to investigate the electrochemical behavior and comprehend alterations occurring on the surface as a result of the CCFE introduction. Moreover, computational analysis through Density Functional Theory (DFT) and Molecular Dynamic simulations (MD) were performed to gain a more comprehensive understanding of the mechanism of electronic adsorption occurring at specific active sites in the presence of the Chrysanthemum Coronarium Flowers compounds.

Evaluation of corrosion inhibition efficiency of chitosan oligosaccharide-derived quaternary ammonium vanillyl aldehyde oligosaccharide derivative for CO2 corrosion control

This study presents the synthesis of a non-toxic, water-soluble chitosan oligosaccharide derivative, quaternary ammonium vanillyl aldehyde oligosaccharide (GCOS), using chitosan oligosaccharide, vanillin, and 2,3-epoxypropyltrimethylammonium chloride as precursors, aimed at serving as a novel eco-friendly corrosion inhibitor. The successful synthesis of the derivative was confirmed through Fourier Transform Infrared Spectroscopy (FTIR) and Proton Nuclear Magnetic Resonance (1H NMR) analysis. The corrosion inhibition properties of GCOS on 20# carbon steel were investigated in a 60 °C CO2-saturated 3.0 wt% NaCl solution employing an array of methods including weight loss measurements, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), electrochemical characterization, and molecular dynamics simulation. Additionally, the synergistic effect of protonated GCOS with halide ion Cl- on corrosion inhibition was analyzed at the molecular level. The results indicated an enhancement in inhibition efficiency with increasing concentrations of the inhibitor. Weight loss measurements showed a maximum inhibition efficiency of 90.9% at 200 ppm of GCOS after 3 days. The adsorption of GCOS on the carbon steel surface was found to follow the Langmuir adsorption isotherm, predominantly through chemisorption. Potentiodynamic polarization measurements classified GCOS as a mixed-type inhibitor, affecting both anodic and cathodic reactions by blocking the active corrosion sites. SEM and AFM analyses confirmed the formation of a protective inhibitor film on the metal surface. Furthermore, molecular dynamics simulations elucidated the synergistic corrosion inhibition effect between the protonated GCOS molecules and Cl- ions in the acidic solution.

Novel N-heterocyclic Schiff base based on Isatin derivative as a sustainable, eco-friendly, and highly efficiency corrosion inhibitor for carbon steel in sulfuric acid medium: Electrochemical and Computational investigation

The present study aimed to synthesize and investigate the inhibitory effects of two novel Schiff bases namely: (Z)− 1-(5-nitro-2-oxoindolin-3-ylidene) semicarbazide (NOSC) and Z)− 1-(5-nitro-2-oxoindolin-3-ylidene) thiosemicarbazide (NOTSC) for carbon steel (CS) corrosion in 0.5 M H2SO4 medium. Through chemical and electrochemical investigations, the efficiency of NOSC and NOTSC's corrosion inhibition was ascertained experimentally at 298 K. It is noteworthy that the inhibitory efficacy of NOTSC and NOSC reached 93.4% and 91.6%, respectively, at a concentration of 10−3 M. Studies using potentiodynamic polarization revealed that NOTSC and NOSC functioned as mixed-type inhibitors. A depressed capacitive loop with varying concentrations is the primary way that the Nyquist plot of impedance is represented. The transportation of corrosive ions to the metal substrate is impeded by the adsorption of both NOSC and NOTSC, as determined by the Langmuir isotherm. Apart from the chemical and electrochemical investigations, additional insights were gained into the inhibitory mechanism by the application of density functional theory (DFT), molecular dynamics simulation (MDS), and an understanding of the molecular structure of NOTSC and NOSC. A robust correlation was discovered between the theoretical and experimental results through the application of DFT/MDS computational study.

Inhibition potential against acetylcholinesterase of commercial and extracts of capsaicin and dihydrocapsaicin by in vitro and in silico studies

The present research investigates the amount of capsaicin and dihydrocapsaicin in three parts of chili extracts (pericarp, seeds, and placenta). Moreover, inhibition potential of capsaicin and dihydrocapsaicin, and chili extracts against AChE were also investigated in vitro and in silico study. The results show that placenta extract had more capsaicin (3818.72 mg/kg DW) and dihydrocapsaicin (2788.37 mg/kg DW) than other extracts. The inhibition potential of dihydrocapsaicin against AChE was higher than that of capsaicin and chili extracts. Which corresponded to the Ki value of dihydrocapsaicin (0.85 mM) higher inhibition potential than that of capsaicin (1.20 mM). The stronger interaction of dihydrocapsaicin than capsaicin at the active site of AChE was also supported by the binding affinity value (−7.8 kcal/mol for dihydrocapsaicin and −7.3 kcal/mol for capsaicin). However, the inhibition modes of dihydrocapsaicin and capsaicin were mixed-type inhibition against AChE. Besides, dihydrocapsaicin and capsaicin were surrounded by aromatic amino acids in the active site of AChE, which caused an increase in fluorescence intensity (FI). A similar increase in FI was also observed in the chili extracts (pericarp, seeds, and placenta). Our results show that capsaicinoids (capsaicin and dihydrocapsaicin) from chili extracts are natural inhibitors of AChE and may be applied to therapeutic Alzheimer's disease.

Ferrous metal corrosion studies in presence of eco-friendly acacia melanoxylon leaves extract in 1M HCl condition

Mild steels are the most widely used type of ferrous metal, but when exposed to corrosive media, they are susceptible to rusting. Recently, researchers have focused on employing environmentally sustainable corrosion inhibitors extracted from plant leaves to protect steel materials against corrosion in acidic regions. This research aims to investigate the prevention of corrosion and surface adsorption strategies of crude acacia melanoxylon extract (AMLE) on mild steel in a 1M HCl environment. AMLE is an exceptionally effective mild steel corrosion inhibitor that has the advantage of being eco-friendly, which was examined using chemical and electrochemical techniques. The mass loss method was used in the study to assess how well the inhibitor performed at various temperatures and doses in a 1M HCl solution. EIS and polarisation experiments were utilized to conduct electrochemical evaluations. The mild steel surface study was projected using the SEM and Contact angle studies and the interaction of active components was elaborated through theoretical quantum chemical techniques. The extract of AMLE contains a large number of phytochemical components that reduce the MS corrosion rate in an acidic solution. At a concentration of 1g/L inhibitor, the highest inhibition effectiveness of 99.35% was attained. Further polarization experimental results noticed that AMLE components function as a mixed-type inhibitor.

Corrosion Prevention of Copper in 2.0 M Sulfamic Acid Using Novel Plant Extract: Chemical, Electrochemical, and Theoretical Studies.

Copper corrosion was suppressed when a lupine extract was immersed in a 2 M sulfamic acid (H2NSO3H) solution. Numerous methods, including mass loss (ML), dynamic potential polarization (PL), and electrochemical impedance (EIS), were employed in these experiments, in addition to theoretical computations such as density functional theory (DFT), Fukui function, and Monte Carlo simulations. Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) were used to analyze the Cu surface's composition and determine its form. Mass loss (ML) was used to examine the inhibition rate of copper corrosion in sulfamic acid at 25 °C in the presence of lupine extract. After examining how it behaved throughout the adsorption process on copper, it was discovered that it follows the Langmuir isotherm and chemical adsorption. An analysis of the PL curves indicates that the lupine extract is a mixed-type inhibitor. It was shown that the inhibitory efficiency increased to 84.2% with increasing lupine concentration. Additionally, as the data show, the efficiency of inhibitors is diminished by increasing temperatures. Theoretical calculations and experimental data were compared using Monte Carlo simulation (MC) and density functional theory (DFT).

Discovery of Hydrazone Scaffolds as Potent and Selective Multitarget‐Directed Ligands for the Treatment of Neurodegenerative Disorders

AbstractIn the current work, new and diverse hydrazone derivatives were designed and synthesized through a facile and multistep synthetic approach. The chemical structures were elucidated by various spectroscopic techniques. In vitro bioactivity analysis demonstrated selective and potent inhibitory potential of hydrazone derivatives against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes. (E)‐3‐chloro‐N′‐(1‐phenylethylidene) benzohydrazide remarkably emerged as a lead candidate exhibiting potent and selective inhibition of AChE with an IC50 value of 0.63±0.01 μM whereas (E)‐3‐chloro‐N′‐(1‐(thiophen‐2‐yl)ethylidene)benzohydrazide delivered the strong potency and selective inhibition towards monoamine oxidase A with an IC50 value of 0.89±0.04 μM. Moreover, (E)‐3‐chloro‐N′‐(1‐(4‐methylthiophen‐2‐yl)ethylidene)benzohydrazide (IC50=2.06±0.01 μM) and (E)‐3‐chloro‐N′‐(1‐(5‐chlorothiophen‐2‐yl)ethylidene)benzohydrazide (IC50=2.06±0.05 μM) were identified as lead inhibitors of monoamine oxidase B. Molecular docking studies of potent and selective inhibitors exhibited various important interactions with amino acid residues in the active pocket of both enzymes, thus strengthening our in vitro results. The kinetics analysis of the most potent compound against AChE revealed non‐competitive mode of inhibition, whereas against monoamine oxidase (A & B), the corresponding lead inhibitors exhibited mixed type of inhibition. Molecular dynamics simulations were also performed to investigate the energetically stable complex formation ability of potent compounds with the target protein. Finally, the results of in silico pharmacokinetic properties showed that the potent compounds have promising pharmacological effects that follow all the parameters of drug‐likeness and could serve as effective drug candidates for future investigations.

Optimization of the corrosion inhibition performance of novel oxadiazole thione-based Schiff base for mild steel in HCl media using Doehlert experimental design

This study aimed to evaluate the effectiveness of 3-((dicyclohexylamino) methyl)-5-(4-((3, 4-dimethoxybenzylidene) amino) phenyl)-1, 3, 4-oxadiazole-2(3H)-thione (DMOT) in inhibiting the deterioration of mild steel in a 1 M HCl solution. Weight loss and electrochemical measurements were used to assess the inhibition performance and synthesis of DMOT. The characterization of DMOT was conducted through NMR and FTIR measurements, while SEM and AFM were used in the surface analysis. DFT calculations were used to investigate the chemical and theoretical properties of DMOT. The results of electrochemical measurements showed that the inhibition efficiency increased as the concentration of the inhibitor increased, with an optimal concentration reaching an inhibition efficiency of 99.17%. Polarization curves revealed that DMOT molecules behaved as a mixed-type inhibitor, with adsorption following the isotherm of Langmuir. The adsorption of DMOT on the corroded metal's surface was verified by SEM and AFM investigations. Using quantum chemical calculations, the quantum chemical properties of the DMOT were evaluated.

Inhibition of Xanthine Oxidase by Pyrazolone Derivatives Bearing a 4-(Furan-2-yl)benzoic Acid Moiety

The pyrazolone-based 4-(furan-2-yl)benzoic acids have been synthesized and studied as xanthine oxidase inhibitors. This enzyme is one of the therapeutic targets for the treatment of hyperuricemia and related diseases. The compounds studied have found to exhibit low micromolar IC50 values relative to the enzyme in vitro, depending on substituents in position 3 of the pyrazolone ring. However, the inhibitory effects observed are reduced in the presence of bovine serum albumin or Tween-80. Among the pyrazolone derivatives synthesized, 4-(5-((3-methyl-5-oxo-1-phenyl-1,5-dihydro-4H-pyrazol-4-ylidene)methyl)furan-2-yl)benzoic acid has been found to be the most potent inhibitor of xanthine oxidase. Kinetic results have shown that this compound is a mixed-type inhibitor with higher affinity to the free enzyme than to the enzyme-substrate complex. The results of the molecular docking and molecular dynamics show that the carboxylic group of the inhibitor can form a salt bridge with Arg880 and a hydrogen bond with Thr1010. These interactions can be key factors in the enzyme-inhibitor complex stabilization.

Long chain imidazole derivative as a novel corrosion inhibitor for Q235 steel in 15 % HCl medium under hydrodynamic condition: Experimental and theoretical examinations

The research in the paper focused in the development of ecologically favorable inhibitor via microwave method. The inhibitor namely N-(2-(2-pentadecyl-2,5-dihydro-1H-imidazole-1-yl)ethyl)palmitamide palmitate, a derivative of imidazole (IPP) was synthesized in one single step and screened its inhibitive property in strongly acidic medium (15 % HCl) for protection of Q235 steel at 1500 rpm rotational speed. The study used for exploring the inhibition effect of IPP includes weight loss, Potentiodynamic polarization, and electrochemical impedance spectroscopy. The estimated results confirmed the inhibition data of 97.41 % and 98.70 % at 308K with 200 mg/L/only IPP and IPP + KI/150 mg/L+0.5 mM respectively, and the influence of temperature has little effect over the inhibition property. The weight loss results show that the IPP belongs to a mixed-type corrosion inhibitor. The SEM, EDX, AFM, SKP, and contact angle analysis results showed that the IPP formed a film on the surface of Q235 steel through adsorption, which changed the hydrophilic and hydrophobic properties of the Q235 steel surface. Further XPS study confirmed the adsorption of IPP molecules over the Q235 steel surface.

Exploration of rigid double schiff base with a symmetrical plane as highly effective corrosion inhibitor for mild steel in hydrochloric acid environment: Experimental and theoretical approaches

A rigid double Schiff base with a symmetrical plane, (1E,1′E)-N,N’-(1,4-phenylene)bis(pyrazin-2-yl)ethanimine) (PBPE), has been synthesized and characterized by 1H NMR and FTIR spectroscopies. The corrosion inhibition performance of PBPE for mild steel in 1.0 mol L−1 HCl solution was systematically measured by weight loss method, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization technique, field emission scanning electron microscopy (FE-SEM), energy dispersive spectrometer (EDS), atomic force microscope (AFM), and water contact angle measurement. The inhibition efficiency depends upon the PBPE concentration and the maximum inhibition efficiency by weight loss analysis is 93.10 % at 800 mg L−1 PBPE. The potentiodynamic polarization measurement revealed that PBPE behaves as a mixed-type inhibitor with a predominant anodic reaction. The thermodynamics adsorption analysis showed the adsorption of the PBPE molecules on the surface of mild steel obeys Langmuir adsorption isotherm, with both physisorption and chemisorption. In the corrosion reaction, the activation energy, activation enthalpy, and activation entropy all increased with increasing PBPE concentration. The surface morphology analysis such as SEM-EDS, AFM, and water contact angle further confirmed adsorption on the mild steel surface and resulted in the formation of protective film on the mild steel surface in PBPE solution. The quantum chemical parameters obtained such as global softness, electron transfer fraction, and energy gap together with Fukui indices can explain the good inhibition efficiency. Molecular dynamics simulations discovered that the PBPE molecules in a flat manner are adsorbed on the surface of mild steel, thus giving rise to a more effective adsorption and corrosion inhibition.