Mixed-type Inhibitor Research Articles

Innovative 8-hydroxyquinoline derivatives as corrosion inhibitors for mild steel in hydrochloric acid: a quantum chemical and experimental study

ABSTRACT This study explores the inhibitory action of two novel organic compounds, namely diethyl 1-((8hydroxyquinolin-5-yl)methyl)−2,6-dimethyl-4-(p-tolyl)−1,4-dihydropyridine-3,5-dicarboxylate (PR1) and diethyl 1-((8-hydroxyquinoline-5-yl) methyl)−2,6-dimethyl-4-(4-nitrophenyl)−1,4dihydropyridine-3,5-dicarboxylate (PR2), on mild steel (MS) corrosion in 1M HCl. Using a combination of quantum chemical and experimental methodologies, the study evaluates the performance of these inhibitors through electrochemical techniques, including potentiodynamic polarisation (PDP) and electrochemical impedance spectroscopy (EIS), complemented by surface analysis via scanning electron microscopy (SEM) and X-ray electron microscopy (EDX). Key findings reveal that both PR1 and PR2 exhibit a significant rise in protection performance with concentration, reaching an impressive peak of 95.3% at 10−3 M for PR2. The inhibitors demonstrate mixed-type inhibition properties and adhere to the Langmuir adsorption isotherm. Detailed surface analysis confirms the creation of a defensive film on the metal surface, correlating with the observed electrochemical results.

Exploring the performance of Coriandrum sativum extract as an effective corrosion inhibitor for mild steel in a [formula omitted] medium, and its sustainable application in the eco-friendly removal of heavy metals

This research investigated the performance of coriander seeds, for the first time, in two critical phenomena: wastewater treatment and corrosion inhibition in acidic environments. On one hand, the aqueous extracts from Coriandrum sativum seeds (CE) were evaluated for mild steel corrosion inhibition in a 2.0 M phosphoric acid medium using several techniques such as phytochemical analysis (GC-MS), potentiodynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy (SEM-EDAX) and theoretical analyses, including DFT calculations and Molecular Dynamic Simulations, further elucidated the major chemical components. First, the phytochemical analysis has proved that CE contains heteroatoms. Second, the electrochemical results indicate that CE behaves as a mixed type inhibitor and the corrosion reaction is controlled by charge transfer process. Finally, The theoretical calculations confirmed that the active compounds of CE can be adsorbed on the Fe (1 1 0) surface through physical patterns and by sharing charges with iron to form coordinate bonds. The acquired results have shown a strong correlation between corrosion inhibition efficiency that was about 93 %, SEM-EDAX and DFT parameters. On the other hand, the study examined coriander seeds (CS) in powder form as a removal of copper ions in aqueous solutions through Atomic Absorption Spectroscopy and Inductively Coupled Plasma analysis. The parametric study was effectuated by establishing the effect of contact time, adsorbent mass, solution pH and stirring speed. The removal rate was about 79 %. Regeneration studies showed that CS could be reused for five cycles without significant loss of effectiveness. SEM-EDAX analysis has proved the studied process.

Exploring synergistic inhibitory mechanisms of flavonoid mixtures on α-glucosidase by experimental analysis and molecular dynamics simulation

The study was the first to evaluate the synergistic interaction of luteolin + quercetin, luteolin + 3-O-methylquercetin, and quercetin + 3-O-methylquercetin mixtures on α-glucosidase and the binding mechanisms were explored using both experimental and theoretical approaches. The results showed that three flavonoid mixtures exhibited a mixed type of inhibition and demonstrated the most potent synergistic effects on α-glucosidase inhibition at 6:4 ratio, with interaction index (γ) of 0.85, 0.78 and 0.73, respectively. The three mixtures had a great influence on α-glucosidase secondary structures. Molecular simulation further demonstrated that three flavonoid mixtures formed hydrophobic interactions and hydrogen bonds with amino acid residues at different sites of α-glucosidase. Collectively, luteolin + quercetin, luteolin + 3-O-methylquercetin and quercetin + 3-O-methylquercetin were found to inhibit α-glucosidase in a synergistic manner and can be potentially used for the development of hypoglycemic food products.

Electrochemical, gravimetric and surface studies of Phalaris canariensis oil extract as corrosion inhibitor for 316 L type stainless steel in H2O-LiCl mixtures

The corrosion inhibition action of Phalaris canariensis extract on 316 L stainless steel in the H2O-35 (wt%) LiCl mixture at different temperatures has been evaluated with the aid of weight loss, potentiodynamic polarization curves, linear polarization resistance and electrochemical impedance spectroscopy tests. These studies were complemented by Fourier Transformed Infrared spectroscopy, FTIR, gas/mass chromatography analytical techniques and detailed scanning electronic microscopy studies. Results have indicated that Phalaris canariensis extract is an efficient inhibitor, with an efficiency that increases with its concentration, but it decreases as the temperature increases. Phalaris canariensis extract is physically adsorbed onto stainless steel according to a Temkin type of adsorption isotherm. Phalaris canariensis extract affected both anodic and cathodic electrochemical reactions with a stronger effect on the anodic ones, acting, thus, as a mixed type of inhibitor. Main compounds contained in the Phalaris canariensis extract were palmitic and oleic acids, responsible for its inhibitory properties.

Electrochemical, surface, and theoretical investigations of palm kernel shell extract as an effective inhibitor for carbon-steel corrosion in 1M HCl solution.

Herein, we employed palm kernel shell extract (PKSE) as an eco-friendly inhibitor for carbon steel in acidic-induced corrosion. The corrosion inhibition of PKSE on carbon steel in 1M HCI solution was investigated by electrochemical impedance spectroscopy, weight loss, and potentiodynamic polarization measurements. The surface was characterized by scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy. Moreover, the elastic modulus and hardness tests were conducted. Weight loss measurements revealed that the optimum concentration of inhibitors is 500ppm with 95.3% inhibition efficiency in 1M HCl solution. Electrochemical results showed that the inhibitor could exhibit excellent corrosion inhibition performance and displayed mixed-type inhibition. The electrochemical impedance spectroscopy analysis shows that the inhibition performance increases by increasing the concentration of PKSE. The surface studies ensure the PKSE effectiveness in carbon steel surface damage reduction. Also, the adsorption of PKSE molecules on the carbon steel surface occurs according to the Langmuir isotherm model. The primary goal of this investigation was the utilization of palm kernel shell extract as corrosion inhibitor for 1018 low carbon steel in 1M HCl solution, which highlights its novelty. The present results will be helpful to uncover the versatile importance of palm kernel shell compounds in the corrosion inhibition process.

Synergistic inhibition effect of diolefinic dye and silver nanoparticles for carbon steel corrosion in hydrochloric acid solution

The current work looks at the inhibitory effects of a diolefinic dye, namely 1,4-bis((E)-2-(3-methyl-2,3-dihydrobenzo[d]thiazol-2-yl) vinyl) benzene iodide salt, in relation to CS corrosion mitigation in hydrochloric acid (HCl) environment. This study uses a variety of experimental methodologies, including weight loss (WL) analysis, electrochemical tests, and theoretical considerations. The synergistic effect of diolefinic dye and AgNPs on the corrosion inhibition of CS in 1 M HCl was investigated. The inhibition efficiency (IE) displays a notable enhancement as the concentration of the dye is elevated and as the temperature raises the IE increases. The diolefinic dye exhibited % IE of 83% even at low concentration (1 × 10–4 M) whereas 90% in the presence of (2.26 × 10–10) AgNPs. Tafel graphs demonstrate that the dye follows a mixed type inhibitor. The adsorption of the dye on CS surface follows Langmuir model. Moreover, the influence of temperature and the activation parameters disclose that diolefinic dye is chemisorbed on the CS surface. The synergistic coefficient of the diolefinic dye and AgNPs under various concentration conditions was greater than unity. The surface morphology of CS sheets was confirmed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Density Functional Theory (DFT) calculations provide theoretical support for the inhibitory effects of the examined dye. Notably, there is a high agreement between the findings of practical studies and theoretical expectations.

Synthesis, structural characterization, thermal analysis and anticorrosion properties of novel AZO-based imidazo[1,2-a]pyridine derivatives: Experimental study and theoretical approaches

In this study, innovative AZO-based imidazo[1,2-a]pyridine derivatives were synthesized using simple and efficient synthetic approach enabling large-scale production. Thermal analysis highlights their suitability for potential applications requiring resistance to moderate temperatures. These compounds were investigated as corrosion inhibitors for MS in a 1 M HCl-medium. Corrosion inhibition studies, including weight loss, PotentioDynamic polarization and electrochemical impedance spectroscopy methods, revealed that AZOs exhibited maximum corrosion inhibition efficiencies reaching 96.13 % and 94.07 %, respectively, at a concentration of 10−3 M and a temperature of 298 K, with both compounds acting as mixed-type inhibitors. The study also delved into the influence of temperature and immersion time on inhibitory performance, revealing stable inhibition within the temperature range of 298–328 K. The calculated standard free energy of adsorption was −42.06 and −40.62 kJ/mol for AZO 1 and AZO 2, respectively, suggesting mixed-type adsorption, with adsorption behavior following the Langmuir isotherm. Morphological analysis through SEM and AFM, showed a reduction in surface roughness in the presence of the inhibitors, while water contact angle measurements indicated a significant increase in surface hydrophobicity. UV–visible and FT-IR analyses confirmed the interaction of AZOs with the MS surface, suggesting the formation of a protective layer composed of adsorbed AZO molecules. Furthermore, computational investigations employing DFT, Monte Carlo, and Molecular Dynamic simulation revealed the formation of coordinate bonds between the studied inhibitors and the metal surface, confirming adsorption on the metallic surface. These findings align well with experimental outcomes, and a possible corrosion inhibition mechanism process was discussed.

Design, synthesis and enzymatic inhibition evaluation of novel 4-hydroxy Pd–C-Ⅲ derivatives as α-glucosidase and PTP1B dual-target inhibitors

A library of 4-Hydroxy Pd–C-Ⅲ derivatives (5a-5p and 8a-8h) as α-glucosidase inhibitors was prepared and the activity of these compounds against α-glucosidase was evaluated. The outcomes displayed that most of the derivatives had moderate to potent α-glucosidase inhibition with IC50 values ranging from 66.3 ± 2.4 to 299.7 ± 6.0 μM. Amongst these compounds, 8a had the strongest α-glucosidase inhibition than others with an IC50 value of 66.3 ± 2.4 μM. Therefore, 8a was chosen to detect the inhibitory activities on PTP1B and α-amylase, the results revealed that 8a had the potential to be PTP1B (IC50 = 47.0 ± 0.5 μM) and α-amylase (IC50 = 30.62 ± 2.13 μM) inhibitor. Additionally, the enzyme kinetic study displayed that 8a was a mixed-type inhibitor. Moreover, the results of the spectroscopy experiments proved that 8a could quench the fluorescence intensity of α-glucosidase in a dose-dependent manner, destroy the secondary structure of α-glucosidase and change the conformation of the enzyme. Significantly, the investigation of cellular thermal shift assay exhibited that 8a could target the PTP1B protein, and the in vitro cytotoxicity discovered compound 8a had no significant toxicity to normal HEK-293 cells. Additionally, the results of molecular docking found that 8a could both bind the active sites of the α-glucosidase and PTP1B. Importantly, the in vivo sucrose-loading test displayed 8a had potential to reduce the postprandial blood glucose. All results proved that compound 8a had great potential as a dual-target inhibitor in treating Type 2 diabetes mellitus.

Eco-friendly corrosion inhibition of copper in NaCl media using Perseana americana extract: Insights from quantum and electrochemical studies

Corrosion of copper in saline environments, particularly in 3.5% sodium chloride (NaCl) solutions, poses significant challenges across various industries, leading to substantial economic losses and safety concerns. Traditional corrosion inhibitors, often synthetic and toxic, raise environmental issues that necessitate the exploration of sustainable alternatives. This study investigates the use of Perseana americana extract (PAE) as an eco-friendly inhibitor for copper corrosion, demonstrating an impressive inhibition efficiency of 96.53% at an optimal concentration of 300 mg/L. Electrochemical assessments, including potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS), reveal that PAE functions as a mixed-type inhibitor, significantly reducing the corrosion current density (icorr) from 3.59 × 10⁻⁵ A/cm2 (without inhibitor) to 1.83 × 10⁻⁵ A/cm2 at 100 mg/L, and further to 0.12 × 10⁻⁵ A/cm2 at 300 mg/L. The adsorption behavior of PAE on the copper surface adheres to the Langmuir isotherm model, indicating monolayer adsorption with a Gibbs free energy of adsorption (ΔGads) of −18.84 kJ/mol, suggesting a predominantly physisorption mechanism. Additionally, Monte Carlo simulations confirm strong interactions between PAE molecules and the copper surface, with the highest adsorption energy recorded for phloretin at −3778.338 kcal/mol, highlighting the extract's potential as a green alternative to conventional inhibitors. This research underscores the viability of utilizing natural plant extracts for effective corrosion control, contributing to more sustainable practices in metal protection.

A novel corrosion inhibitor of bis-benzimidazole derivative for mild steel: Synthesis, properties and mechanism investigation

The application of corrosion inhibitor is still one of the effective ways to protect metals under high temperature and high pressure environment. In this paper, we have introduced a synthetic method for a novel bis-benzimidazole derivative, i.e., N, N-bis (-2-heptadecyl-benzimidazole) -1-hexylammonium chloride (HBH), and its solubility was improved by adding a specific surfactant (AEO-5) to form a highly efficient corrosion inhibitor system (HBH-A), and its corrosion inhibition was studied by weight loss, electrochemical measurements, SEM, EDS and XRD. The results showed that HBH-A inhibited the corrosion of N80 carbon steel in the corrosive medium. As the concentration of HBH-A increases, the corrosion inhibition rate exhibits a pattern of rapid initial growth followed by a slower increase. Electrochemical measurements demonstrate that HBH-A behaved as an effective mixed-type corrosion inhibitor, exhibiting a significant enhancement in the corrosion inhibition rate (η) with increasing concentrations of HBH-A. At a HBH-A concentration of 100 mg⋅L-1, the inhibition rate can outstrip 98%. Corrosion surface analysis further confirm that the HBH molecules are indeed adsorbed to form an adsorption film, and the surface exposure of N80 carbon steel was significantly decreased with the action of HBH-A, thus reducing the corrosion rate of N80 carbon steel.

Insights into inhibitory action and interaction of bisdemethoxycurcumin on tyrosinase: Spectroscopic and docking analysis

Bisdemethoxycurcumin (BDMC), a demethoxy derivative of curcumin, has garnered interest for its potential anti-tyrosinase properties, which are crucial for applications in food preservation and cosmetic industries. Despite its recognized bioactive effects, the detailed inhibitory action and interaction of BDMC on tyrosinase and its application in anti-browning processes remain unclear. This study aims to dissect the molecular interactions of BDMC with tyrosinase, elucidate its inhibition mechanism, and assess its efficacy in preventing browning, thereby underpinning its potential as a natural anti-browning agent. Employing a battery of spectroscopic techniques, we characterized the interaction of BDMC with tyrosinase. The anti-browning properties of BDMC were evaluated on fresh-cut apples, and its effect on enzymatic activities related to browning was also investigated. The results indicate that BDMC interacts with tyrosinase in a reversible mixed-type inhibition manner with an IC50 value of 12.5 ± 0.2 μM. Surface Plasmon Resonance (SPR) results indicated that BDMC presented good binding affinity toward tyrosinase. Fluorescence quenching results showed that BDMC could quench the fluorescence of tyrosinase in a static process. Synchronous fluorescence, circular dichroism spectra, and three-dimensional fluorescence results indicated that interaction of BDMC against tyrosinase resulted in changes of tyrosinase on microenvironment and conformation, thus causing decrease of tyrosinase activity. Copper-chelating results presented that BDMC could chelate to copper with stoichiometric ratio of 1: 2. Molecular docking provided intricate details of how BDMC interacted with tyrosinase. Moreover, BDMC exhibited anti-browning capability on fresh cut apples, and could regulate PPO, POD, and APX activities. The comprehensive analysis proposed in this study consolidated the theoretical basis of BDMC as a tyrosinase inhibitor and supported its potential anti-browning application.

The fine structural changes of phenolic hydroxyl groups of cinnamic acid and its derivatives affects their inhibition mechanism and interaction with α-glucosidase

Cinnamic acid (CCA), p-coumaric acid (PCA), and caffeic acid (CA) are natural phenolic compounds and extensively utilized in the food industry. PCA and CA are both derivatives of CCA and share comparable molecular structures. In this study, the inhibitory mechanisms of CCA, PCA, and CA on α-glucosidase was investigated by employing inhibition kinetics and molecular docking analyses. Our results revealed that CCA (IC50 = 6.12 ± 0.056 mM) and CA (IC50 = 2.02 ± 0.083 mM) exhibited mixed-type inhibition, while PCA (IC50 = 3.82 ± 0.095 mM) exhibited non-competitive inhibition. The intermolecular energy values of CCA, PCA, and CA with α-glucosidase were determined to be −7.11, −7.94, and −8.14 kcal/mol, respectively, indicating their binding to α-glucosidase via hydrophobic interactions and hydrogen bonding, among which CA has the greatest binding ability. Fluorescence quenching results and circular dichroism (CD) spectra further confirmed the higher affinity of CA to α-glucosidase than that of CCA and PCA. These outcomes shed light on the importance of molecular structure differences in α-glucosidase inhibition and highlight the potential scope for developing low-glycemic-index functional foods.

Extract of Silybum marianum (L.) Gaertn Leaves as a Novel Green Corrosion Inhibitor for Carbon Steel in Acidic Solution

In this work, leaves of Silybum marianum (L.) Gaertn were extracted by a one-step extraction method using ethanol as a solvent, and the Silybum marianum (L.) Gaertn extract (SMGE) was firstly employed as a green corrosion inhibitor for carbon steel in 0.5 mol/L H2SO4. The corrosion inhibition performance was studied using weight loss and electrochemical methods, and the anti-corrosion mechanism of SMGE is further analyzed through some surface characterizations and theoretical calculations. The results indicate that SMGE can act as a mixed-type corrosion inhibitor and possess superior corrosion inhibition performance for carbon steel in H2SO4 solution, and the optimum corrosion inhibition efficiency reached 93.06% at 800 ppm SMGE combined with 60 ppm KI. The corrosion inhibition efficiency increased with the rising inhibitor concentration. Surface characterizations illustrated that the inhibitor could physico-chemically adsorb on a metal surface, forming a hydrophobic, protective film.

Inhibition mechanism of buckwheat hulls polyphenols on α-amylase and α-glucosidase using kinetics, spectroscopics and molecular docking approaches

The work investigated the activity inhibition of phenolic compounds in buckwheat (Fagopyrum esculentum Moench) hulls (BH) on α-amylase and α-glucosidase, and clarified their possible mechanisms based on kinetics, spectroscopics and molecular docking analysis. The total polyphenols (BHP) from BH using an ultrasound-assisted alcohol extraction method was 210.50 mg GAE/g DW. The study identified a total of 33 polyphenolic compounds in the extracts of BH using UPLC-Q-Exactive Orbitrap/MS, revealing that sixteen of these were novel polyphenolic substances not previously documented in this plant. BHP demonstrated significant inhibitory effects on both α-amylase and α-glucosidase enzymes, with IC50 values recorded at 27.16 μg/mL and 7.00 μg/mL, respectively, suggesting noncompetitive and mixed-type inhibition mechanisms. The fluorescence intensity of the enzymes was effectively quenched by BHP through a combination of dynamic and static quenching mechanisms, driven predominantly by hydrophobic interactions. BHP's interaction with the enzymes resulted in conformational changes that reduced their enzymatic activities. Molecular docking further revealed that six polyphenolic components of BHP had a strong affinity for binding with the active sites nestled in the enzymes' hydrophobic cavities, inhibiting their activity and potentially contributing to a reduction in blood glucose levels. The results could provide perspective for using BHP in the functional components of sugar-controlling foods.

Assessment of the inhibition performance of ZIF-8 on corrosion Mitigation of API 5L X65 steel in 3.5 wt% NaCl: Experimental and theoretical insight

The synthesis and application of ZIF-8 as an effective corrosion inhibitor for the corrosion of API 5L X65 steel in 3.5 wt% NaCl have been studied. The synthesized ZIF-8 was characterized using some surface probe approaches, which include field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR TEM), and X-ray photoelectron spectroscopy (XPS), respectively. The results showed that ZIF-8 exhibited regular hexagonal and orthorhombic-shaped nanoparticles. An approximately 62% yield was achieved. Electrochemical studies such as open circuit potential (OCP), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) were performed. The polarization results show that ZIF-8 is a mixed-type inhibitor, revealing a strong impact on both the anodic and cathodic polarization current values. The EIS studies reveal an increase in the charge transfer resistance upon the introduction of ZIF-8. The existence of a strong protective film adsorbed on X65 steel was recognized via XPS and FT-IR analysis. The highest inhibition efficiency value of 98.1% was recorded at a concentration of 0.120 wt% ZIF-8. Quantum chemical computations in the framework of DFT and molecular dynamic simulation were used to determine the reaction sites on the inhibitor, and as such, in-depth insight into the reaction mechanism was revealed.

Insight into the corrosion inhibition performance of dimethyldiallylammonium chloride acrylamide copolymer for mild steel in acidic solution

Dimethyldiallylammonium chloride acrylamide (DADMAC-AAM) copolymer was firstly applied as a novel corrosion inhibitor for carbon steel in acidic solution. Electrochemical, theoretical and computational methods were performed to illustrate the corrosion inhibition mechanism of DADMAC-AAM. Results of electrochemical tests indicated that DADMAC-AAM effectively slowed down corrosion rate of mild steel in HCl solution as a mixed-type corrosion inhibitor. Its corrosion inhibition efficiency increased with dosage, and the maximum value reached about 92.44 % with adding 100 mg/L. In-situ scanning vibration electrode technique illustrated that the corrosion inhibition performance of DADMAC-AAM increased with immersion time. Metal surface was covered with a dense hydrophobic film due to the physical-chemical adsorption of DADMAC-AAM molecules, and the adsorption behavior obeyed to the Langmuir adsorption isothermal model. Theoretical calculations were carried out to explain the corrosion inhibition mechanism, and the increase of active energy indicated that the strong inhibitive action of DADMAC-AAM molecule could be due to the increase of activation energy barrier of corrosion reaction. Results obtained from computational simulations proved that DMDMAC-AAM molecules adsorbed on metal surface through interactions between N or O and Fe atoms. This adsorption film could retard the invasion of corrosive species, thus protecting metal from corrosion.

Synthesis of new binary trimethoxyphenylfuran pyrimidinones as proficient and sustainable corrosion inhibitors for carbon steel in acidic medium: experimental, surface morphology analysis, and theoretical studies

In this study, synthesis and assessment of the corrosion inhibition of four new binary heterocyclic pyrimidinones on CS in 1.0 M hydrochloric acid solutions at various temperatures (30–50 °C) were investigated. The synthesized molecules were designed and synthesized through Suzuki coupling reaction, the products were identified as 5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-trione (HM-1221), 2-thioxo-5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)dihydropyrimidine-4,6(1H,5H)-dione (HM-1222), 1,3-diethyl-2-thioxo-5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)dihydropyrimidine-4,6(1H,5H)-dione (HM-1223) and 1,3-dimethyl-5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-trione (HM-1224). The experiments include weight loss measurements (WL), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). From the measurements, it can be shown that the inhibition efficiency (η) of these organic derivatives increases with increasing the doses of inhibitors. The highest η recorded from EIS technique were 89.3%, 90.0%, 92.9% and 89.7% at a concentration of 11 × 10−6 M and 298 K for HM-1221, HM-1222, HM-1223, and HM-1224, respectively. The adsorption of the considered derivatives fit to the Langmuir adsorption isotherm. Since the ΔGoads values were found to be between − 20.1 and − 26.1 kJ mol−1, the analyzed isotherm plots demonstrated that the adsorption process for these derivatives on CS surface is a mixed-type inhibitors. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscope (AFM) and Fourier- transform infrared spectroscopy (FTIR) were utilized to study the surface morphology, whereby, quantum chemical analysis can support the mechanism of inhibition. DFT data and experimental findings were found in consistent agreement.Graphical

Harnessing dual-mode RIPK1 ligands for cross-species anti-necroptosis inhibitor compounds

Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) has a crucial role in cell death and inflammation. A promising approach to develop novel inhibitors of RIPK1 mediated necroptosis is to mix the different binding modes of the known RIPK1 inhibitors into one molecule. Herein we report the synthesis and biological evaluation of novel mixed type inhibitors. Using Eclitasertib as a starting point, and applying our previous, published knowledge regarding cyclic malonamides, we successfully identified a library of active compounds. The active enantiomer of the most balanced and promising compound was subjected to pharmacokinetics and in vivo hypothermia study in mice.

The corrosion inhibition performance of a diissocyanate-imidazole based organic compound during acid cleaning of MSF desalination plant

Inorganic scale formation is a common issue in multi-stage flash (MSF) desalination plants, significantly impacting operational efficiency. To address this, acid cleaning is frequently employed, but it can lead to severe corrosion of alloy components if not properly controlled with corrosion inhibitors. This study investigates the effectiveness of toluene-2,4-diisocyanate-4-(1H-imidazole-ly) aniline (TDIA) as a corrosion inhibitor for 304L stainless steel in a simulated acid cleaning solution (1M HCl and 3.5 % NaCl). A range of tests, including electrochemical analysis, weight loss measurements, and surface characterization techniques such as AFM, EDS, and SEM, were used to assess the inhibitor's performance at temperatures of 25, 45, 65, and 90 °C. At a concentration of 50 ppm, TDIA achieved inhibition efficiencies of around 90% at 25 °C and above 80% at 90 °C, demonstrating effective protection across all temperatures studied. The adsorption behavior of TDIA followed the Langmuir adsorption model, and it acted as a mixed-type inhibitor by forming a protective layer on the metal surface, which prevents corrosive agents from accessing the steel. The dual-environment testing method, simulating conditions in desalination plants, offers valuable insights into the inhibitor's practical performance, enhancing the applicability of these findings to real-world industrial scenarios.

A study on the corrosion inhibition impact of newly synthesized quinazoline derivatives on mild steel in 1.0 M HCl: Experimental, surface morphological (SEM-EDS and FTIR) and computational analysis

Two new quinazoline derivatives were investigated in this research, namely 12-(4-methoxyphenyl) and 3,3-dimethyl-12-(4-nitrophenyl)-3,4,5,12-tetrahydrobenzo[4,5]imidazo[2, 1-b]quinazolin-1(2 H)-one (Q-NO2). In 1 M hydrochloric acid (HCl), −3,3-dimethyl-3,4,5,12-tetrahydrobenzo[4,5]imidazo[2,1-b]quinazolin-1(2 H)-one (Q-OMe) proved to be an extremely effective corrosion inhibitor for mild steel. The maximum inhibition efficiencies of 94.7 % for Q-NO2 and 96.7 % for Q-OMe were achieved when the performance of the inhibitors was evaluated using potentiodynamic polarization (PDP), electrochemical frequency modulation (EFM) and electrochemical impedance spectroscopy (EIS). According to these findings, the Q-NO2 and Q-OMe molecules have a remarkable ability to generate a dense, resistant protective film on the mild steel surface. This protective film acted as a barrier, effectively blocking the penetration of corrosive ions and their interaction with the mild steel substrate. The adsorption characteristics of these inhibitors on the mild steel surface conform to the Langmuir adsorption isotherm. PDP experiments show that Q-NO2 and Q-OMe act as mixed-type inhibitors for mild steel in 1.0 M HCl. Surface characterization by energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) determined that a protective layer had formed on the steel surface, preventing corrosion. The experimental results were corroborated by theoretical insights from density functional theory (DFT), which further clarified the molecular adsorption processes. This work highlights the potential of Q-NO2 and Q-OMe as effective inhibitors to protect mild steel in acidic situation.