Despite the growing interest in self-assembled organic coatings for corrosion protection, the mechanisms governing their interfacial organization and stability under varying conditions remain poorly understood. In this work, a functional self-assembled organic coating based on a thiophene-substituted cyclohexenone derivative, namely ethyl (E)-2-oxo-6-(thiophen-2-yl)-4-(2-(thiophen-2-yl)vinyl)cyclohex-3-ene-1-carboxylate (TVCH), was developed via a simple, low-cost dip-coating strategy to enhance the corrosion protection of carbon steel (CS) in aggressive environments. The molecular design of TVCH, featuring conjugated π-systems and heteroatom-rich functional groups, promotes strong interfacial interactions and controlled self-assembly into a compact protective layer. Surface characterization (SEM/EDS and FT-IR) confirmed the formation of a uniform, defect-minimized coating with a hierarchical branched morphology, enabling effective surface coverage and barrier properties. Electrochemical impedance spectroscopy revealed high corrosion resistance, with inhibition efficiency reaching ∼95% in 3.5 wt% NaCl solution, while moderate degradation was observed in 1 M HCl due to increased medium aggressiveness. Temperature-dependent analysis combined with Arrhenius–Eyring modeling indicated a medium-dependent adsorption mechanism, involving predominantly physisorption in saline solution and enhanced chemisorption in acidic media. Density functional theory (DFT)-based calculations further demonstrated strong charge-transfer interactions between TVCH molecules and the steel surface, supported by favorable HOMO–LUMO characteristics and electrostatic potential distribution. The superior performance of the coating is attributed to the synergistic effect of interfacial coordination, π–metal interactions, and intermolecular cohesion, leading to the formation of a stable self-assembled barrier layer. This work provides a rational strategy for designing efficient organic coatings through molecular engineering and self-assembly for sustainable corrosion protection applications.

A novel indole-based compound, (E)-2-(1H-indole-3-carbonyl)-3-((4-nitrophenyl)amino)acrylonitrile (ICNA), was synthesized through an energy-efficient Q-Tube high-pressure protocol and evaluated as a corrosion inhibitor for carbon steel in 15% hydrochloric acid (HCl). Structural identity was confirmed by Fourier-transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy (1H NMR). Corrosion performance was assessed using weight-loss (WL), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) techniques, while surface morphology and composition were examined by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and FT-IR analyses of the adsorbed film. ICNA achieved an inhibition efficiency of 98.64% at 7.5 x 10-4 M and 30 degrees C, with efficiency increasing with concentration and slightly decreasing with temperature. Time-dependent WL measurements further showed that ICNA maintains high inhibition efficiency during prolonged immersion (up to 6 h), confirming the stability of the protective film. Adsorption followed the Langmuir isotherm, indicating monolayer formation through mixed physisorption and chemisorption, supported by quantum chemical calculations. The synergistic effect of iodide ions (I-) further enhanced protection efficiency. Compared with the conventional thermal route, the Q-Tube synthesis provided a faster, more efficient, and higher-yield pathway. This study represents the first successful application of Q-Tube technology for indole-based inhibitor synthesis, offering a practical and sustainable route for high-performance corrosion inhibitors in aggressive acidic environments.

The development of environmentally benign and high-performance organic coatings (OC) capable of providing durable corrosion protection under aggressive conditions remains a significant challenge for metallic infrastructures. In this study, a novel water-based self-assembled OC was fabricated on carbon steel (CS) using 4-allyl-2-methoxyphenyl-4-methylbenzenesulfonate (MBS) through a simple dip-coating process, offering a sustainable alternative to conventional solvent-based protective systems. The spontaneous molecular organization during deposition promoted the formation of a compact and continuous flower-like hierarchical coating, which effectively isolated the CS substrate from corrosive environments. The morphology, composition, and structure of the fabricated coating were comprehensively characterized using complementary surface analytical techniques, confirming the successful formation of a homogeneous and adherent protective layer. The anticorrosion performance was systematically evaluated in both 1.0 M HCl and 3.5 wt.% NaCl solutions by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). Electrochemical measurements demonstrated a remarkable enhancement in corrosion resistance after coating deposition, as evidenced by a substantial increase in total resistance ( together with a pronounced reduction in corrosion current density () and corrosion rate (). The slight displacement of the corrosion potential () indicated that the fabricated coating acts predominantly as a mixed-type protective layer by simultaneously suppressing the anodic dissolution of steel and the cathodic reduction reactions. The corresponding inhibition efficiency exceeded 93% in both chloride-containing environments, confirming the excellent protective capability of the developed coating. The theoretical investigation revealed favorable frontier molecular orbital characteristics, efficient donor-acceptor behavior, and strong coordination interactions between the MBS molecules and the surface atoms, promoting synergistic molecular self-assembly and the formation of a stable and compact protective architecture. The excellent correlation between theoretical assessments and experimental findings confirmed the stability, efficiency, and real-system relevance of the developed OC, highlighting its potential for practical anti-corrosion applications.

The present study examined the corrosion inhibition property of two derivatives of 8-hydroxyquinoline, namely diethyl 1,1-(4-(4-chlorophenyl)-1-((8-hydroxyquinoline-5-yl)methyl)-2, 6-dimethyl-1, 4-dihydropyridine-3,5-diyl) diethanone (P1) and diethyl 1,1-(4-(4-bromophenyl)-1-((8-hydroxyquinoline-5-yl)methyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-diyl)diethanone (P2). against mild steel (MS) degradation in 1.0 M hydrochloric acid (HCL) solution. The study was carried out using electrochemical techniques such as dynamic potential polarisation (DPP) and impedance spectroscopy (EIS) at different temperatures (298-328 K). Inhibition efficiency (IE %) increased with inhibitor concentration, reaching 97.0% for P1 and 91.8% for P2 at 10-3 M (298 K). Impedance measurements indicated that charge transfer resistance (Rct) increased, while double-layer capacitance (Cdl) decreased with increasing concentration of P1 and P2. Analysis of the polarisation curves shows that P1 and P2 act as mixed-type inhibitors. According to the Langmuir isotherm and thermodynamic parameters, P1 and P2 are adsorbed onto the mild steel surface by chemical interactions. The SEM/EDX analysis results revealed the formation of an adsorption film on MS. DFT calculations show that free heteroatom doublets of oxygen (O) and nitrogen (N) promote electron sharing between the molecules studied and the steel surface. Data from theoretical methods (DFT) confirm the experimental results. La pr & eacute;sente & eacute;tude a examin & eacute; la propri & eacute;t & eacute; d'inhibition de corrosion de deux d & eacute;riv & eacute;s de l'hydroxyquinol & eacute;ine-8, & agrave; savoir la di & eacute;thyl 1,1-(4-(4-chloroph & eacute;nyl)-1-((8-hydroxyquinol & eacute;ine-5-yl)m & eacute;thyl)-2,6-dim & eacute;thyl-1,4-dihydropyridine-3,5-diyl)di & eacute;thanone (P1) et la di & eacute;thyl 1,1-(4-(4-bromoph & eacute;nyl)-1-((8-hydroxyquinol & eacute;ine-5-yl)m & eacute;thyl)-2,6-dim & eacute;thyl-1,4-dihydropyridine-3,5-diyl) di & eacute;thanone (P2), contre la d & eacute;gradation de l'acier doux (MS) dans une solution d'acide chlorhydrique (HCl) 1.0 M. On a r & eacute;alis & eacute; l'& eacute;tude & agrave; l'aide de techniques & eacute;lectrochimiques telles que la polarisation potentiodynamique (PDP) et la spectroscopie d'imp & eacute;dance (EIS) & agrave; diff & eacute;rentes temp & eacute;ratures (298 & agrave; 328 K). L'efficacit & eacute; de l'inhibition (% IE) augmentait avec la concentration d'inhibiteur, atteignant 97.0% pour P1 et 91.8% pour P2 & agrave; 10-3 M (298 K). Les mesures d'imp & eacute;dance ont indiqu & eacute; que la r & eacute;sistance au transfert de charge (Rct) augmentait, tandis que la capacitance de la double couche (Cdl) diminuait avec l'augmentation de la concentration de P1 et de P2. L'analyse des courbes de polarisation montre que P1 et P2 agissent comme des inhibiteurs de type mixte. Selon l'isotherme de Langmuir et les param & egrave;tres thermodynamiques, P1 et P2 sont adsorb & eacute;s sur la surface de l'acier doux par interactions chimiques. Les r & eacute;sultats de l'analyse de MEB/EDX ont r & eacute;v & eacute;l & eacute; la formation d'un film d'adsorption sur le MS. Les calculs de la th & eacute;orie fonctionnelle de la densit & eacute; (DFT) montrent que les doublets d'h & eacute;t & eacute;roatomes libres d'oxyg & egrave;ne (O) et d'azote (N) favorisent le partage d'& eacute;lectrons entre les mol & eacute;cules & eacute;tudi & eacute;es et la surface de l'acier. Les donn & eacute;es des m & eacute;thodes th & eacute;oriques (DFT) confirment les r & eacute;sultats exp & eacute;rimentaux.

Background: Corrosion of brass in saline environments poses significant challenges, especially in industries that depend on metal durability. This study introduces two newly synthesized water-soluble organic compounds, 5(((R)-2-hydroxy-2-((2R,3S,4R,5S)-3,4,5-trimethoxytetrahydrofuran-2-yl)ethoxy)methyl)quinoline-8-ol (P3) and 5-(((R)-2-((2R,3S,4R,5S)-4,5-dimethoxy-3-(tetradecyloxy)tetrahydrofuran-2-yl)-2-hydroxyethoxy)methyl)quinolin-8-ol (P4), as corrosion inhibitors. These compounds are designed leverage their structural features and solubility to improve adsorption on brass surfaces, thereby preventing corrosion in saline conditions. The study evaluates their practical application and explores the molecular mechanisms behind their protective behavior. Methods: Corrosion inhibition by P3 and P4 was evaluated in a 3 % NaCl solution using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). Surface morphology and protective layers characteristics were examined using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). Computational techniques such as Density Functional Theory (DFT) and Molecular Dynamics (MD) simulations, were used to analyze molecular interactions at the atomic level. Significant Findings: Both P3 and P4 demonstrated excellent inhibition efficiencies, with P4 reaching 97.6 % at a 10-3 M. Electrochemical analyses revealed that both act as mixed-type inhibitors via adsorption mechanisms consistent with the Langmuir isotherm. Surface analysis confirmed the formation of protective film. Computational simulations supported experimental results by findings revealing strong molecular interactions with the brass surface.

The corrosion protection of Al (AA2024-T3) and its alloys in chloride-containing environments remains a major challenge due to the aggressive action of chloride ions, which can induce localized degradation and compromise the long-term durability of metallic structures. In the present study, the corrosion-inhibitory performance of two organic inhibitors, diethyl(1H-indazol-7-yl)amino(4-methoxyphenyl)methylphosphonate (DIMMP) and diethyl (3a,7a-dihydro-1H-indazol-7-yl)amino(furan-2-yl)methylphosphonate (DIFMP), was systematically investigated to protect AA2024-T3 in a 3.5 wt% NaCl medium. The inhibitory efficiency and adsorption behavior of the selected compounds were evaluated through a combination of electrochemical techniques, surface characterization analyses, and theoretical calculations to establish a comprehensive understanding of the corrosion protection mechanism. The experimental results demonstrated that both inhibitors significantly reduced the corrosion rate of AA2024-T3 by forming a compact and adherent protective layer on the metal surface, thereby limiting charge transfer processes and hindering the penetration of aggressive chloride ions. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) analyses revealed a marked increase in polarization resistance (Rp) and a substantial decrease in corrosion current density (icorr) in the presence of the inhibitors, indicating enhanced corrosion resistance and remarkable inhibition efficiencies of 95.8% and 95.5% at 10(-3) M for DIMMP and DIFMP, respectively. Surface examinations further confirmed the formation of a homogeneous protective film and the mitigation of corrosion-induced surface deterioration. Adsorption studies suggested that the inhibition process predominantly occurs through the spontaneous adsorption of inhibitor molecules onto the Al surface, leading to the establishment of an effective barrier against corrosive species. Density Functional Theory (DFT) calculations provided molecular-level insights into the adsorption mechanism, highlighting the crucial role of electron-rich heteroatoms and it-electron systems in strengthening the interaction between inhibitor molecules and the Al substrate. Theoretical findings exhibited excellent agreement with experimental observations, confirming the superior adsorption affinity and protective capability of the investigated inhibitors. The synergistic integration of experimental and computational approaches demonstrates that the studied inhibitors constitute promising and environmentally benign candidates for enhancing the corrosion resistance of Al in saline environments. These findings contribute to the rational design of high-performance corrosion inhibitors and provide valuable insights into the development of sustainable strategies for the protection of Al-based materials in aggressive chloride media.

Despite the engineering potential offered by the integration of hybrid (organic and inorganic) materials, organic compounds with metal surfaces, in protecting corrosion-prone metals from harsh conditions, the interaction mechanisms between these components and their in-situ formation to induce nature-inspired composites remain insufficiently understood. In this study, an environmentally friendly organic coating (OC) was developed and applied to carbon steel (CS) substrates via a dip-coating process using an aqueous solution containing 2-amino-4(4-chlorophenyl)-1-(1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl)-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carbonitrile (oh-HQc) compound. Surface characterization techniques, including SEM-EDX and FTIR, confirmed the successful deposition and chemical integrity of the as-synthesized OC. These results also demonstrate a strong interfacial affinity of oh-HQc molecules for the CS surface, facilitating the nucleation of a petal-like structure through active adsorption sites onto the CS surface. Subsequently, the fundamental formation mechanism governing the nucleation and oh-HQc self-assembly behavior, reactivity, and their adsorption behavior were analyzed based on advanced theoretical calculations. Owing to the oh-HQc donor-acceptor sites, the tested system with three oh-HQc fragments promotes the controlled growth of uniformly distributed flower-like structures via molecular self-assembly and inter/intra-fragmentation interactions. The as-fabricated OC was exposed to different aggressive media, including 1.0 HCl, 3.5 wt% NaCl, and 1.0 M H2SO4 environments to evaluate their electrochemical, short-term/long-term stability, and anticorrosion performance. This flower-like structure demonstrated superior anticorrosion performance, achieving an inhibition efficiency of approximately 95 % in 1.0 M HCl, 90 % in 3.5 % NaCl, and 51 % in H2SO4 environments. Our eco-conscious approach paves the way for a deeper exploration of the structural and functional potential of hydroxyquinoline (HQ) derivatives in the fabrication of advanced organic materials, not only characterized by remarkable properties but also benefiting from facile synthetic methodology, which is of paramount importance for industrial implementation.

The aim of this project is to synthesize two novel imidazole-based corrosion inhibitors, OEtPh-imidazole and ClPh-imidazole, and to examine their performance in protecting mild steel in a 1 M HCl solution. The structure of the inhibitors was confirmed using FTIR and NMR spectroscopy. Electrochemical methods, such as PDP and EIS, have demonstrated remarkable inhibition capacity, reaching approximately 98-99 % at an ideal concentration of 10-3 M. This performance is due to the creation of a stable protective coating that slows down anodic dissolution and the cathodic reaction of hydrogen evolution. Theoretical calculations based on DFT and MC simulations confirm intense chemisorption interactions between the inhibitors and the Fe (110) surface, mainly through nitrogen atoms and aromatic pi electrons. The Langmuir isotherm model is followed during the adsorption process, with negative values of Delta G degrees ads (<=-40kJ & sdot;mol-1), indicating spontaneous chemisorption. Surface analyses (SEM/EDS) confirmed a dense and uniform protective coating, reducing roughness and corrosion residues. Therefore, OEtPh-imidazole and ClPh-imidazole appear to be promising candidates for long-term corrosion protection in acidic environments. These findings open the door to further research, particularly in a real industrial context, and to the development of new, more effective and environmentally friendly imidazole derivatives.

This study investigates the effect of barium oxide (BaO) incorporation on the structural, optical, thermal, and radiation shielding properties of bismuth-borate glasses. Various characterization techniques, including X-ray diffraction (XRD), optical absorption spectroscopy, Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy, were employed to analyze the glasses. The radiation shielding properties, which are crucial for applications in photonics and radiation protection, were also thoroughly assessed. The physical analysis revealed that the addition of BaO resulted in an increase in the glass density (rho), from 5.712 g/cm3 to 6.121 g/cm3, while the molar volume (Vm) decreased from 130.328 cm3/mol to 44.364 cm3/mol. XRD confirmed the amorphous nature of the samples. Thermal analysis demonstrated that as BaO content increased, both the glass transition temperature (Tg) and crystallization temperature (Tc) also rose. FTIR and Raman spectroscopy revealed absorption bands corresponding to structural units such as [BO4], [Bi-O-Bi], and [BiO6], indicating a depolymerized glass network. Optical analysis showed that the bandgap energy for direct transitions decreased from 2.80 eV to 2.52 eV with increasing BaO content. This change aligns with the observed structural modifications, suggesting the formation of non-bridging oxygen atoms. Radiation shielding properties, evaluated using Phy-X simulations, indicated a significant enhancement in radiation shielding efficiency, particularly at low energies. For instance, at 0.284 MeV, the mass attenuation coefficient (MAC) decreased from 0.430 cm2/g for the base glass to 0.259 cm2/g for the glass containing 0.8 mol of BaO. Additionally, the linear attenuation coefficient (LAC) dropped from 2.456 cm-1 for Ba0 to 1.586 cm-1 for Ba0.8. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analyses revealed that higher BaO concentrations led to greater surface heterogeneity and granular formations. These results suggest that BaO-incorporated bismuth-borate glasses exhibit improved structural, optical, and radiation shielding properties, making them promising candidates for photonic and radiation protection applications.

Corrosion of mild steel in acidic environments represents a persistent challenge in various industrial sectors, often resulting in premature material failure and substantial maintenance costs. In this study, two novel quinoline-based derivatives 5-(butoxymethyl)-2-methylquinolin-8-ol (Q1) and 5-((3-aminopropoxy) methyl)-2-methylquinolin-8-ol (Q2) were synthesized and systematically evaluated as corrosion inhibitors for mild steel in 1M HCl. The inhibitors' performance was assessed through potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS), both of which confirmed their effectiveness in suppressing corrosion processes. Notably, Q1 and Q2 achieved inhibition efficiencies of approximately 91.3% and 95.1%, respectively, at optimal concentrations. Adsorption studies demonstrated that the adsorption behavior adhered to the Langmuir isotherm model, suggesting monolayer coverage and a spontaneous, chemically favorable adsorption mechanism, with Delta G degrees ads values of-42.41 kJ/mol for Q1 and-43.27 kJ/mol for Q2. Surface analysis via SEM-EDX demonstrated significant improvements in surface morphology, including visible film formation and reduced corrosion damage. Complementary density functional theory (DFT) calculations revealed favorable electronic properties, with Q1 and Q2 showing Delta E values of 4.43 and 4 eV, respectively, indicating high reactivity. The EHOMO and ELUMO values further supported their electron-donating and accepting capabilities. These findings demonstrated that both quinoline derivatives significantly reduced corrosion rates, with inhibition efficiencies exceeding 90% at optimal concentrations. Moreover, the integration of experimental and theoretical findings highlights Q2's potential as an effective, molecularly engineered anticorrosion agent. These insights contribute to a promising pathway for the development of high-performance, eco-friendly inhibitors tailored for use in acidic industrial environments.

Carbon steel (C-steel) protection in acidic environments remains a significant challenge in industrial applications. In this study, applying dibenzalacetone derivatives remains the most practical solution to mitigate C-steel corrosion in acidic conditions, as demonstrated by the excellent performance of 1,5-p-tolylpenta-1,4-dien-3-one (p-TPO) and its high ability to control the corrosion kinetics of C-steel in 1.0 M HCl solution. The electrochemical response shows that p-TPO forms a durable protective layer on the C-steel surface, achieving an exceptional inhibition efficiency of 97% at a low concentration of 5 x 10-3 M, and significantly reduces anodic and cathodic current densities, as indicated by potentiodynamic polarization (PDP) measurements. According to electrochemical impedance spectroscopy (EIS) analysis, the polarization resistance values increased with increasing concentration of inhibitor, confirming the effectiveness of p-TPO in reducing corrosion rate. Corrosion measurements demonstrated improved electrochemical stability against chloride ions. The addition of the p-TPO inhibitor resulted in the formation of a hybrid film with a corrosion current density of 24.49 x 10- 6 A/cm2 and a high corrosion resistance of 734.60 Omega & sdot;cm2 at a concentration of 5 x 10- 3 M and a temperature of 303 K. The long-term protection and thermal stability were assessed, indicating remarkable stability up to approximately 318 K, and maintained high inhibition efficiency over 72 h of immersion as indicated by a polarization resistance of 318.30 Omega & sdot;cm2. This exceptional performance highlights their potential for sustained corrosion protection under an aggressive environment. The adsorption of p-TPO was found to follow the Langmuir adsorption isotherm. Additionally, Mott-Schottky analysis is employed to gain insights into the interfacial properties of the passive film formed on the C-steel surface. The micro-pores and cracks (without p-TPO) were eliminated (with pTPO), as confirmed by the results of SEM/EDS analyses. Theoretical calculations based on density functional theory (DFT), and density functional-based tight-binding (DFTB) suggest that p-TPO adsorbs parallelly onto the C-steel surface via carbonyl oxygen and aromatic pi-electrons, forming a stable protective layer that effectively shields the metal from corrosive attack. The findings enhance the comprehension of the adsorption mechanisms of p-TPO as cost-effective and environmentally friendly alternatives for corrosion protection in harsh acidic environments, providing valuable insights into their potential effectiveness in mitigating corrosion processes for practical applications, and offering useful insights for developing advanced materials for industrial corrosion control.

Hydrogen-bonded organic frameworks (HOFs) are a class of crystalline porous materials that are primarily synthesized through the self-assembly of organic or metal-organic building blocks via intermolecular hydrogen bonding interactions. These materials have garnered significant attention for their potential in low-carbon, energy-efficient separation processes, particularly in the areas of adsorption and membrane separation. The inherent capability of HOFs for solution processing further enhances their versatility, allowing for the fabrication of adsorbents and membranes with tailored microstructures that can be fine-tuned to meet specific separation requirements. Recent advancements in HOF-based membranes have focused on innovative strategies for material preparation, including the selection of suitable building blocks, the optimization of synthesis conditions, and the development of new classification techniques. In this context, a comprehensive analysis of recent advancements in the design and synthesis of HOF-based membranes, emphasizing novel material engineering strategies has been discussed. Furthermore, the potential of HOF-based membranes, governed by their physicochemical properties and hierarchical self-assembly, is systematically examined in this review. Finally, the challenges and future prospects of HOF-based membranes are systematically analyzed, with a focus on structural stability, performance optimization, and advanced functionalization strategies to enhance their high-precision applicability in high-precision separation.

The present article examines the inhibitory efficiency of two synthesized amine-based organic molecules, namely 11-(2-chlorophenyl)-3,3-dimethyl-2,3,4,5,10,11-hexahydro-1H-dibenzo[be][1,4]diazepin-1-one (CDHD) and 3,3-dimethyl-11-phenyl-2,3,4,5,10,11-hexahydro-1H-dibenzo[be][1,4]diazepin-1-one (DPHD), in reducing the corrosion of mild steel in a 1 M hydrochloric acid solution. These inhibitors were synthesized and characterized by NMR spectroscopy, and their corrosion inhibition performance was evaluated using gravimetric and electrochemical techniques, including open circuit potential (OCP), Tafel polarization, and electrochemical impedance spectroscopy (EIS). Potentiodynamic polarization curves showed that the tested compounds act as mixed- type inhibitors. EIS analyses indicated that the charge transfer resistance increased from 22.7 Omega.cm2 to 397.8 Omega. cm2 and 606.2 Omega & sdot;cm2 at a concentration of 10-3 M of CDHD and DPHD, respectively. Additionally, it was found that the adsorption of both compounds on the mild steel surface follows the Langmuir adsorption isotherm equation. These compounds also retained their inhibition efficiency at high temperatures. Surface morphology and elemental composition analyses of steel samples, performed using scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS), confirmed the formation of a barrier layer covering the mild steel surface. Furthermore, quantum chemical calculations using density functional theory (DFT) provided insights into the reactivity and adsorption characteristics of the inhibitors, validated by molecular dynamic simulations. The study highlights the high efficiency of both inhibitors, with inhibition efficiencies reaching 95.9 % for DPHD at a concentration of 10- 3 M, emphasizing their potential as environmentally friendly corrosion inhibitors for industrial applications.

Covalent organic frameworks (COFs) represent an advanced class of crystalline materials, distinguished by their modular design and precise atomic-level arrangement. Since their discovery in 2005, COFs have been subjected to significant evolution, leading to advanced three-dimensional structures and scalable synthesis approaches. These features enable COFs to function as efficient heterogeneous photocatalysts, integrating the benefits of homogeneous catalyst precision with the robustness of heterogeneous systems. This progress has shown their potential for addressing critical environmental challenges. In this study, the development of COFs is reviewed, focusing on their molecular-level design of COFs to optimize key photocatalytic processes, including light absorption, charge separation, and surface reaction dynamics. COFs are examined for their roles in environmental remediation, such as pollutant adsorption, catalytic transformation, and water treatment, with particular attention to their photocatalytic applications in water splitting and contaminant degradation. Challenges related to large-scale fabrication and practical deployment are discussed alongside emerging prospects, such as integrating COFs with digital technologies like artificial intelligence to optimize design and performance. These insights confirm the transformative potential of COFs as sustainable materials for pollution control and environmental restoration.

In this study, a biofunctional composite, chitosan-GA-cellulose composite (CGAC), was synthesized through a cross-linking process involving chitosan and cellulose, using glutaraldehyde (GA) as the cross-linking agent. The final composite material was tested for the removal of the pollutant methylene orange dye. The structural and chemical properties of the carbohydrate-based composite were investigated using several techniques, including XRD, SEM, EDX, TGA and FTIR. The results show that the synthesized material has good textural properties and high temperature resistance. Equilibrium results were well described by the Langmuir isotherm. Under optimal conditions, specifically, an initial MO concentration of 100 mg/L, a contact time of 80 min, and a pH of 4.4, the maximum removal efficiency of MO reached 98.9 %, with an adsorption capacity of 324.62 mg/g. Even after five regeneration cycles, the removal efficiency remained high at 83.4 %, demonstrating the adsorbent's strong reusability. To further understand the interfacial interactions and adsorption behavior of methyl orange (MO) on the synthesized CGAC composite, density functional theory (DFT) calculations were employed. These theoretical investigations provided a comprehensive understanding of the adsorption mechanism by elucidating the electronic properties, structural formation, and fundamental bonding interactions between MO and CGAC. The DFT analysis revealed critical insights into charge distribution, donor-acceptor interactions, and adsorption energy, offering a deeper perspective on the stability and efficiency of MO removal by CGAC material. The as-prepared carbohydrate-based composite exhibits significant potential for wastewater treatment because of its high adsorption efficiency, environmentally friendly composition, and sustainable nature.

This study investigated the effectiveness of two piperidine-based compounds, piperidine-2-carboxylic acid (PPC) and piperazine-2-carboxylic acid (PPR) derivatives, as corrosion inhibitors in a 15 % hydrochloric acid (HCl) solution. To assess their performance, experiments on weight loss, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) were conducted at 313 K. In the EIS tests, the maximum values of 95 % for PPR and 88 % for PPC derivatives revealed that the inhibition efficiency increased with increasing inhibitor concentration. According to the PDP analysis, both inhibitors behaved as mixed-type agents, impacting both anodic and cathodic processes. SEM examination revealed the production of a compact, homogeneous protective coating on the steel surface, and the adsorption behavior was consistent with the Langmuir isotherm. To obtain a deeper understanding of the molecular mechanisms underlying corrosion inhibition, complementary theoretical investigations utilizing computational techniques such as density functional theory (DFT), density functional tight binding (DFTB), and molecular dynamics (MD) simulations were performed. These investigations primarily focused on the analysis of molecular orbital energies and adsorption behavior on the N80 steel surface.

Nickel chloride functionalized chitosan was prepared using a solid-state dispersion technique. This was used as an efficient, cost-effective and mild heterogeneous catalyst for the synthesis of a series of substituted pyridines using an environmentally friendly method, by reacting aldehydes with methyl acetoacetate esters and ammonium acetate in refluxing EtOH. The 1,4-dihydropyridines formed were then oxidized in a one-pot reaction with acetic acid to the corresponding pyridine derivatives. XRD, FTIR, SEM, EDX and ATG analyses were used to characterize the catalyst material. The advantages of this catalytic system include simplicity of processing, the use of environmentally friendly solvent, short reaction times (25-30 min), moderate reaction conditions and excellent yields (74-93 %). Without chromatographic separation, the reaction product is easily separated in pure form. In addition, the Cs@NiCl2 catalyst was reused for more than three cycles for the synthesis of pyridine derivatives without significant loss of yield.

Despite the potential engineering benefits of the concurrent presence of organic substances in protecting vulnerable metallic materials from corrosive environments, both their interaction and the mechanism underlying the formation of the functional protective film remains less understood. For this purpose, (1E,4E)-1,5-diphenylpenta-1,4-dien-3-one (DPO) and 2,6-bis((E)-4-chlorobenzylidene)cyclohexan-1-one (CBO) were synthesized and employed as environmentally friendly inhibitors for C38 steel in a 15 % HCl solution. The aim was to regulate the corrosion kinetics and investigate how the geometric structure resulting from the heterocyclization of dibenzylideneacetone affected its interaction with the metallic surface. Weight loss method and electrochemical measurements were evaluated to estimate the protective behavior of DPO and CBO molecules and to build an excellent anti-corrosion system. The outcomes revealed that CBO inhibitors exhibited high resistance compared to DPO molecules. This performance is described by an inhibition percentage of 96 % at a concentration of 10-3 M. Indeed, this outcome can be explained by the presence of chloride atoms, as well as the cyclic ring enhancing the surface coverage by these molecules. The barrier film resulting from the adsorption of CBO inhibitors provides strong prevention and extraordinary corrosion performance. Computational calculations based on density functional theory (DFT), density functional based tight-binding (DFTB), and molecular dynamic (MD) simulations were performed to predict the interfacial mechanism and adsorption behavior of DPO and CBO on the metal surface. These advanced computational techniques enable a thorough examination of the interactions between the organic inhibitors and the metal substrates, offering insights into both the mechanistic pathways and energetics involved in the adsorption process. The results reinforce the understanding of the adsorption mechanisms of DPO and CBO, shedding light on how these substances may effectively mitigate corrosion processes in practical applications.