Quantum Chemical Molecular Dynamics Research Articles

Revisiting the Enhanced Chemical Reactivity in Water Microdroplets: The Case of a Diels-Alder Reaction.

Often, chemical reactions are markedly accelerated in microdroplets compared with the corresponding bulk phase. While identifying the precise causative factors remains challenging, the interfacial electric field (IEF) and partial solvation are the two widely proposed factors, accounting for the acceleration or turning on of many reactions in microdroplets. In sharp contrast, this combined computational and experimental study demonstrates that these two critical factors have a negligible effect on promoting a model Diels-Alder (DA) reaction between cyclopentadiene and acrylonitrile in water microdroplets. Instead, the acceleration of the DA reaction appears to be driven by the effect of confinement and the concentration increase caused by evaporation. Quantum chemical calculations and ab initio molecular dynamics simulations coupled with enhanced sampling techniques predict that the air-water interface exhibits a higher free-energy barrier of this reaction than the bulk, while external electric fields marginally reduce the barrier. Remarkably, the catalytic capability of the IEF at the water microdroplet surface is largely hampered by its fluctuating character. Mass spectrometric assessment of the microdroplet reaction corroborates these findings, suggesting that the DA reaction is not facilitated by the IEF as increasing the spray potential suppresses the DA products by promoting substrate oxidation. While the DA reaction exhibits a surface preference in water microdroplets, the same reaction tends to occur mainly within the core of the acetonitrile microdroplet, suggesting that the partial solvation is not necessarily a critical factor for accelerating this reaction in microdroplets. Moreover, experiments indicate that the rapid evaporation of microdroplets and subsequent reagent enrichment within the accessible confined volume of microdroplets caused the observed acceleration of the DA reaction in water microdroplets.

Vapour–liquid equilibrium using quantum chemical molecular dynamics simulation and radial distribution function analysis

AbstractInstead of the classical molecular simulation widely implemented for estimating the vapour–liquid equilibrium (VLE), a quantum chemical (QC) molecular dynamics simulation was applied to the VLE estimation in three typical systems that include a deep eutectic solvent (DES) and an ionic liquid (IL). In addition, a radial distribution function (RDF) was derived from the QC simulation to examine the molecular behaviour in the liquid phase. A mean absolute error of 2.72% was obtained from the QC simulation compared to the experimental data. The RDF analysis explains the relative volatility increase of the acetic acid and water binary system with the propyl acetate solvent. This analysis indicated that the DES mixture comprising glycerol and choline chloride facilitated the separation of water and i‐propanol. The interaction between water and ethyl sulphate pair with the help of 1‐ethyl‐3‐methylimidazolium as an IL is stronger than that between ethanol and water, which explains how the IL improves ethanol and water separation in the vapour phase.

Corrosion resistance and forming mechanism of phytic acid conversion film on copper foil prepared by electrolysis

In this paper, the phytic acid conversion film was prepared on copper foil by electrolysis for the first time. Its morphology and chemical composition were characterized by SEM, EDS, FTIR and XPS, and its corrosion resistance was evaluated using electrochemistry. Finally, the formation mechanism of the phytic acid conversion film on the surface of copper foil and its corrosion resistance mechanism were revealed by quantum chemical calculations and molecular dynamics simulations. The results show that the phytic acid conversion film on the surface of copper foil prepared by electrolysis is uniform and dense. The electrochemical impedance value of copper foil in 3.5 wt% NaCl solution increased from 3956 Ω·cm2 to 24828 Ω·cm2 after the preparation of phytic acid conversion film, and the protection efficiency reached 91 %. During the electrolysis process, copper atoms are oxidized into copper ions, which can be coordinated with phytate ions to form negatively charged complexes. Under the action of electric field force, these complexes move toward the anode copper foil, and finally adsorbed on the surface of the anode copper foil to form phytic acid conversion film. The molecular dynamics show that the adsorption configuration of the phytic acid molecule on Cu(111) surface changed from perpendicular to parallel, and the binding energy increased from 234.87 kJ/mol to 354.23 kJ/mol after applying an electric field, Therefore, the phytic acid conversion film prepared on the surface of copper foil by electrolysis has good corrosion resistance. This study provides a new method for the rapid preparation of phytic acid conversion film with excellent performance on metal surface.

Efficient separation of diisopropyl ether and ethanol using green solvents: Thermodynamic analysis and process simulation

Ionic liquids (ILs) and deep eutectic solvents (DESs) were first proposed as green solvents to study and compare their azeotropic separation effects in diisopropyl ether (DIPE) and ethanol (EA). The COSMO-RS model was used to screen ILs/DESs, and the feasibility of the extractants were comprehensively analyzed in terms of viscosity, thermal stability, and toxicity. Experiments were carried out on selected ILs and DESs, and the results showed that the separation effect of ILs was significantly stronger than that of DESs. Quantum chemical calculations and molecular dynamics simulations were combined to comprehensively analyze and compare the microscopic mechanisms of extraction separation. Based on the experimental data, a DIPE-EA extraction-coupled separation process was designed. For the first time, life cycle analysis was used to comprehensively evaluate the impact of this process on human health and the environment from multiple perspectives, providing theoretical guidance for the separation of alcohol ethers in the industry.

Computational and Experimental Comparison of Molecularly Imprinted Polymers Prepared by Different Functional Monomers-Quantitative Parameters Defined Based on Molecular Dynamics Simulation.

In recent years, the advancement of computational chemistry has offered new insights into the rational design of molecularly imprinted polymers (MIPs). From this aspect, our study tried to give quantitative parameters for evaluating imprinting efficiency and exploring the formation mechanism of MIPs by combining simulation and experiments. The pre-polymerization system of sulfadimethoxine (SDM) was investigated using a combination of quantum chemical (QC) calculations and molecular dynamics (MD) simulations. MIPs were prepared on the surface of silica gel by a surface-initiated supplemental activator and reducing agent atom transfer radical polymerization (SI-SARA ATRP). The results of the QC calculations showed that carboxylic monomers exhibited higher bonding energies with template molecules than carboxylic ester monomers. MD simulations confirmed the hydrogen bonding sites predicted by QC calculations. Furthermore, it was observed that only two molecules of monomers could bind up to one molecule of SDM, even when the functional monomer ratio was up to 10. Two quantitative parameters, namely, the effective binding number (EBN) and the maximum hydrogen bond number (HBNMax), were defined. Higher values of EBN and HBNMax indicated a higher effective binding efficiency. Hydrogen bond occupancies and RDF analysis were performed to analyze the hydrogen bond formation between the template and the monomer from different perspectives. Furthermore, under the influence of the EBN and collision probability of the template and the monomers, the experimental results show that the optimal molar ratio of template to monomer is 1:3. The method of monomer screening presented in this study can be extended to future investigations of pre-polymerization systems involving different templates and monomers.

Temperature dependent stochastic dynamics mass spectrometric analysis of configurationally locked polyenes

This paper derived relation between mass spectrometric variable intensity of analyte peaks and three-dimensional molecular structures of ions toward temperature utilising innovative stochastic dynamics equations, which provide exact analyte quantification and 3D structural analysis and are attractive formulas for modelling of mass spectrometric phenomena. The same equations are opened to develop new relations accounting for temperature; thus, providing argumentation about temperature dependent variables. High-temperature measurement of vapours are important tool, amongst others and use the Arrhenius’s plot. However, there is a variation between experimental and theoretical linear correlation toward temperature; thus, highlighting soft ionisation methods showing significant standard deviations. It could be explained with temperature perturbation of charge values. Descriptive models, so far, provide semi-quantification. This study, first shows validity of new functional model. Straightforwardly, its empirical proof is obtained determining 3D structurally protomers and isotopomers of configurationally locked polyenes via ultra-high resolution electrospray ionization and atmospheric pressure chemical ionization mass spectrometry within the temperature range T=300-450°C. There are used high accuracy quantum chemical static methods, molecular dynamics and chemometrics. There are excellent method performances (|r|=0.99978). The tool could be regarded as an actually honest alternative of available theoretical models.

Interaction Analysis by Fragment Molecular Orbital Method for Drug Discovery Research.

The use of computational methods in drug discovery research has increased substantially in recent years. Computational chemistry techniques, such as quantum chemical calculations and molecular dynamics simulations, continue to be widely used. In this review, we focused on drug discovery-related studies that employ fragment molecular orbital methods. Furthermore, we focused on inhibitor discovery, protein-protein interaction analysis, including antigen-antibody interaction analysis, and integration with molecular dynamics simulations.

Electrochemical and surface investigations of N, S codoped carbon dots as effective corrosion inhibitor for mild steel in acidic solution

Mild steel is a versatile, inexpensive, highly flexible, and easily weldable material widely used in construction, pipelines, transportation, shipping, and other industries. However, it is also extremely susceptible to corrosion processes under the influence of weather phenomena, posing a significant threat to society and human health. In this work, we investigated the corrosion inhibition capacity of a new type of N, S codoped carbon dots (N, S-CDs) on Q235 carbon steel in the acidic medium. The goal product was synthesized by hydrothermal method using o-phenylenediamine and amidinothiourea as precursors. Combined with electrochemistry, Fourier transform infrared (FTIR) spectroscopy, scanning electrochemical microscopy (SECM), and theoretical calculations, the inhibition properties of N, S-CDs on Q235 carbon steel in HCl solution were evaluated. The potentiodynamic polarization (PDP) curves and electrochemical impedance spectroscopy (EIS) results indicated that the corrosion inhibition efficiency reached 90.3 % and 92.4 % at 100 mg/L concentration, respectively. Indeed, the presence of N, S-CDs reduced the electric double-layer capacitance, increased the thickness of the adsorption film on the carbon steel surface, and reduced the corrosion current density, resulting in a delay of corrosion. X-ray photoelectron spectroscopy (XPS) analysis and surface characterization confirmed the successful doping of N, S and the formation of adsorption films, the Langmuir adsorption isotherm also confirmed the superior inhibition of N, S-CDs on the surface of Q235 carbon steel through physical and chemical adsorption mechanisms. At the same time, quantum chemical calculations and molecular dynamics (MD) simulations revealed its inhibition mechanism at the molecular/atomic level.

Scale inhibition mechanism of itaconic acid-sodium methacrylate sulfonate on calcite: Quantum chemical calculation and molecular dynamics simulation

In order to explore the scale inhibition mechanism of green scale inhibitor-itaconic acid-sodium methacrylate sulfonate (IA-SMAS) on calcium carbonate (CaCO3), the scale inhibition characteristics of IA-SMAS were studied by quantum chemical calculation and molecular dynamics simulation. The charge distribution, electrostatic potential distribution, geometric matching degree and frontier molecular orbital energy of IA-SMAS were analyzed by quantum chemical calculation. It was found that IA-SMAS molecules have the ability to bind to Ca2+ at the micro level, occupy the growth active sites of crystal during the growth of calcite crystal planes, and inhibit the normal growth of crystal. Based on the molecular dynamics simulation method, the effects of IA-SMAS concentration on the adsorption configuration, radial distribution function and interaction energy in the binding process of IA-SMAS with calcite crystal planes were analyzed. The results show that the area of calcite crystal planes covered by IA-SMAS molecules, the peak value of radial distribution function and the binding energy increase with the increase of IA-SMAS concentration. However, the relative concentration of water molecules near the calcite crystal planes decreases, and the trend of water molecules moves away from the crystal planes of calcite. It indicates that the high concentration of IA-SMAS molecules can occupy the position of water molecules, and enhance the scale inhibition efficiency. Therefore, the scale inhibition performance of IA-SAMS increases with the increase of its concentration in a certain range, and an appropriate increase in IA-SMAS concentration can effectively inhibit the growth of scale.

Effect of water on CO2 capture and phase change in non-aqueous 1,4-butanediamine/ethylene glycol biphasic absorbents: Role of hydrogen bond competition

Non-aqueous liquid–solid biphasic absorbents show significant potential for reducing energy consumption in CO2 capture. However, the high hygroscopic nature of amine compounds and the approximately 10 % to 20 % water vapor in natural gas plants’ flue gases challenge their efficiency and stability. This study investigated water’s effects on the CO2 absorption/desorption performance, phase-change behavior, and products of the non-aqueous absorbent 1,4-Butanediamine (BDA)/ethylene glycol (EG). Experimental results show that water significantly impacts absorption/desorption performance. The maximum CO2 loading and regeneration efficiency were 1.4199 mol·mol−1 and 89.85 %, respectively. Water leads to the gradual disappearance of phase changes, with solid-phase CO2 loading decreasing from 0.008 to 0.004 mol·g−1. Quantitative NMR demonstrates that carbamates and CO32-/HCO3- are the main CO2-related products in aqueous systems, with their relative proportions affected by water content. Quantum chemical calculations and molecular dynamics simulations reveal that water enhances absorption efficiency by participating in the catalytic environment and reaction process. Water-induced hydrogen bonding competition is the leading cause of weakened interactions between species. Specifically, H-bonds between carbamate/protonated amines were decreased by 23.94 %. The enhanced solvation effect reduces aggregation of the key products, contributing to the gradual disappearance of phase changes. This study provides insights into water’s effect on non-aqueous biphasic absorbents at the molecular level, offering a theoretical foundation for the development and optimization of absorbents suitable for use with steam-containing flue gases.

Structure and interactions of CO2 with reline (a 1:2 choline chloride – Urea mixture) according to quantum chemical calculations and molecular dynamics simulation

Quantum chemical DFT calculations [B3LYP+GD3/6-311++g(2d,2p)] of the structure and interactions in various complexes of CO2 molecule with a choline cation, a chloride anion, urea molecules, a choline chloride ion pair and a 1:2 choline chloride – urea complex were carried out. The contributions of Coulomb and van der Waals interactions were calculated. The QTAIM method was used to evaluate the strength of various bonds. A molecular dynamics simulation of CO2 molecules in reline in the NPT ensemble (1 atm, 298 K) was also carried out. The radial distribution functions of the particle centers of mass, local mole fraction functions, spatial distribution functions, and density profiles were calculated. Stronger interactions, compared to the other DES components, were observed in case of the chloride anion and the CO2 molecule according to the DFT calculations. However, in the system, stronger interactions were observed between the chloride anion and the system components, namely NHCl and OHCl hydrogen bonds. This made the chloride anion inaccessible and unable to interact with the CO2 molecule, according to the MD simulation results. Additionally, the presence of a fairly extensive surface layer containing DES and CO2 molecules was shown.

Crystallization resolution of racemic compounds via chiral surfactant

As one of the basic attributes of nature and the universe, chirality is valuable in biology, medicine, and materials science. However, enantiomer resolution remains a long-standing challenge. Herein, a novel surfactant for resolution of racemic compound with high performance has been outlined. Firstly, we synthesized a chiral surfactant and its chiral recognition ability to L-Alanine molecules was confirmed. Subsequently, the solid–liquid equilibrium curves were used to design the resolution route. The synthesized surfactant was further utilized to intensify the crystallization process of the racemic compound, resulting in a remarkable increase of L-Alanine products’ ee values from 0% to 99%. Finally, quantum chemical calculations and molecular dynamics simulations were employed to uncover the stereoselectivity recognition mechanism of surfactant to L-Alanine molecules. Overall, we propose a new idea for direct crystallization resolution of racemic Alanine by chiral surfactants that differs from the “rule of reversal”, which is highly attractive for chiral resolution.

Effect of linking group on the corrosion inhibition performance of triazine-based cationic Gemini surfactants: Experimental and theoretical investigation

Three kinds of triazine-based cationic Gemini surfactants (TCGSII, TCGSIV and TCGSVI) with different lengths of the linking group were synthesized and characterized by FT-IR, 1H NMR and ESI-MS. The surface activity test showed that the surface activity of the surfactants decreased with the increase in the length of the linking group from 2 to 6. At the same concentration, the corrosion inhibition rate decreased with the increase in the length of the linking group, decreasing in the following order: TCGSⅡ > TCGSⅣ > TCGSⅥ. The corrosion inhibition effect of 0.2 mM TCGSⅡ reaches 98.03 %. The adsorption of the synthesized surfactants on the surface of carbon steel conforms to the Langmuir adsorption isotherm, and included physisorption and chemisorption on the metal surface. Quantum chemical calculations and molecular dynamics simulations verify this conclusion.

Thiourea derivatives as efficient inhibitors for the corrosion of cold rolled steel in citric acid solution: experimental and computational studies

The prediction of the corrosion inhibition properties of organic compounds from experimental and computational results is a highly interesting field. Correct understanding of substituents or electronic effects can significantly contribute to the design of efficient inhibitors. In this research article, the corrosion inhibitory performance of thiourea (TU), 1,3-dimethylthiourea (DMTU), N-ethylthiourea (ETU), and 1-p-tolylthiourea (p-TTU) in 1.0 M citric acid (H3C6H5O7) solution for cold rolled steel (CRS) was fully investigated by experimental measurements and theoretical calculations. The results show that the inhibition performance of p-TTU exhibits the best inhibition property among these four thiourea derivatives with a maximum inhibition efficiency of 97.36%. The inhibition ability follows the order of p-TTU > DMTU > ETU > TU. Potentiodynamic polarization curves indicate that all these thiourea derivatives are mixed-type inhibitors, where TU, ETU and DMTU mainly inhibit the cathodic reaction, but p-TTU effectively retards both cathodic and anodic reactions. Nyquist mainly appears a depressed capacitive loop, and the charge transfer resistance increases significantly with the addition of thiourea derivatives. The adsorption of four thiourea derivatives on CRS surface conforms to Langmuir adsorption isotherm. The micrographs from SEM and metallurgical microscopy further support the protection effectiveness of thiourea derivatives on the steel surfaces. Quantum chemical calculations and molecular dynamics simulations can well elucidate the relationship between molecular structure and inhibition efficiency for the studied thiourea derivatives.

Simultaneous absorption of CO2 and H2S by [Emim][Ac]: The competition mechanism

In this work, ionic liquid (IL), 1-ethyl-3-methylimidazolium acetate ([Emim][Ac]) was used for simultaneous absorption of H2S and CO2 from mixed gases. According to the results, there was a competitive relationship between H2S and CO2. The CO2 capacity of simultaneous absorption, less than 0.010 mol/mol IL is much lower than that of individual absorption, 0.294 mol/mol IL, at 40 °C and 101 kPa with 50 vol% CO2 in gases. And the H2S/CO2 selectivity during individual absorption (Sideal) was significantly different from that during simultaneous absorption (Ssim). Ssim could reach 75.3, which was about 40 times of Sideal. The increase of temperature can increase Sideal, but has almost no obvious influence on Ssim. The decrease of volume fraction can increase Sideal, but decrease Ssim. The competitive mechanism in [Emim][Ac] is proposed and verified by the characterization, quantum chemical (QC) calculation and molecular dynamics (MD) simulation. The results show that the presence of H2S prevented the formation of “carbene” in [Emim][Ac] that can react with CO2 for chemical absorption. This work provides new insights into simultaneous absorption of H2S and CO2 by ILs.

Molecular interaction mechanism and process analysis of separation of cyclohexane/ethyl acetate by extractive distillation

The selection of efficient and environmentally friendly extractants is crucial for extractive distillation (ED), and the microscopic mechanism of extractants in ED is still unclear. For the benefit of interpreting the microstructure distribution and phase behavior of the mixed system, this paper studied it by quantum chemical (QC) calculation and molecular dynamics (MD) simulation. Firstly, 1,3-dimethylimidazolium hexafluorophosphate [Mmim][PF6], 1-ethyl-3-methylimidazolium hexafluorophosphate [Emim][PF6] and organic solvent DMSO were screened based on COSMO-RS model and relative volatility. The bond length, bond energy, total electron density and deformation charge density of [Mmim][PF6], [Emim][PF6], DMSO extractant and ethyl acetate were analyzed by QC, the intrinsic properties of the chosen extractant and azeotropic system, as well as the interactions among the three extractants and ethyl acetate, were investigated. Then, the effect of extractant on the separation performance of cyclohexane ethyl acetate azeotrope in solvent environment was further studied by MD simulation. The two-dimensional mass density distributions (ANDDs) visualized the mixing behavior and structural distribution of the three extractants with the azeotropic system in the ternary system respectively, and the hydrogen bonding statistics indicated a high number of hydrogen bonds between [Mmim][PF6] and ethyl acetate. The radial distribution function (RDF) indicated that the extraction effect of [Mmim][PF6] was better and [PF6-] played a dominant role in the separation of azeotropic system. The strong interaction between [Mmim][PF6] extractant [PF6-] and ethyl acetate was further verified by the spatial distribution function (SDF). Ultimately, through Aspen Plus software simulation, it was found that the [Mmim][PF6] extractive distillation process was superior to the traditional solvent DMSO process, TAC was reduced by 8 %, and gas emissions were reduced by 5 %. Through the combination of QC, MD, and process simulation offer theoretical guidance for the efficient separation of the cyclohexane-ethyl acetate system and provide a specific reference value for the selection of the optimal extractant.

Enhanced corrosion resistance performance of the novel tripodal imidazolium-based ionic liquid: Experimental and theoretical investigations

The imidazolium-based ionic liquids (ILs) were widely recognized as the eco-friendly corrosion inhibitors. Many literatures focused on enhancing the corrosion inhibition efficacy via the modification of various functional groups to ILs. The present study investigated the corrosion resistance performance of the novel synthesized tripodal IL ([(C4im)3TA][Cl3]) with a triazine spacer and three imidazolium cations for mild steel (MS) in 1 M HCl solution. The inhibition efficiencies of [(C4im)3TA][Cl3] at the concentrations of 0.1 mM (55.7 ppm, 80 %) and 0.5 mM (278.5 ppm, 86 %) were found to be comparable to, and higher than that of conventional imidazolium-based ILs 1‑butyl‑3-methylimidazolium chloride (C4mimCl) at 10 mM (1747 ppm, 81 %), respectively. The adsorption behavior of [(C4im)3TA][Cl3] at the metal surface was reflected through X-ray photoelectron spectroscopy, and the adsorption mechanism was further investigated using quantum chemical calculations and molecular dynamics simulations. The results indicated the greater ability of [(C4im)3TA][Cl3] to form chemical bonds with Fe atoms, which induced the generation of the more stable hydrophobic protection film at the surface. This study presented the novel concept for the structural design of high-efficiency corrosion inhibitors based on imidazolium ILs.

Preparation of magnetic core-shell Fe3O4@MBT-LDH composite and its application as an effective inhibitor for carbon steel

The core-shell structural Fe3O4@MBT-LDH was synthesized via the ion exchange method, with MBT (2-mercaptobenzothiazole) inhibitor ions intercalated lamellar ZnAlCe-LDH attaching closely to the Fe3O4 microspheres surface. The morphology, composition, structure, and magnetic properties of the composite were measured by transmission electron microscope, X-ray diffraction, Fourier transform infrared spectra, and vibrating sample magnetometer. The release behavior of MBT ions and corrosion inhibition performance of the Fe3O4@MBT-LDH under “no MF” (without an external magnetic field) and “MF ON” modes (under an external magnetic field) were measured by UV–vis spectroscopy, electrochemical tests, scanning electron microscopy, and X-ray photoelectron spectrometer (XPS). Calcinating the composite after the release test and redispersing the sintered products in MBT ions-containing solution, the composite was reestablished. Results showed that the Fe3O4@MBT-LDH possessed moderate MBT loadings amount (12.0%) and presented strong superparamagnetic properties with saturation magnetization (Ms) of 27.6 emu⋅g−1. The release behavior of the MBT− from the composite was sustainable and could be further slowed down by using an external magnetic field with changing the release mechanism. The release curve reached equilibrium with a longer time of 48 h and a lower release amount of 57.0% under MF ON mode than that of no MF mode with a time of 7 h and a release amount of 74.7%. The Fe3O4@MBT-LDH owned a good and long-term protection performance for Q235 carbon steel with maximum corrosion inhibition efficiency (ηe) of up to 93.30%. As a promising controlled-release inhibitor, it could be recycled and regenerated by simple treatment, still having high ηe higher than 80% and excellent magnetic properties with Ms of 21.47 emu⋅g−1 after five cycles. The corrosion mechanism for carbon steel was further analyzed by quantum chemical calculations and molecular dynamics simulation.

A study of pomegranate peel extract effect on corrosion inhibition performance on aluminum in HNO3 solution

Green corrosion inhibitors have an important role in reducing the corrosion rate of metals and the effects of toxic chemicals in the environment. In this study, the inhibition effect of pomegranate peel extract (PPE) with concentration of 0.5, 1, 1.5, 2, 2.5 and 3 g/L on the aluminum 1050 alloy corrosion behavior in the nitric acid solution investigates using the weight loss, electrochemical techniques, scanning electron microscope (SEM), atomic force microscope (AFM), contact angle images, gas chromatography-mass spectrometer (GC-MS) analysis, fourier transform Infrared spectroscopy (FTIR) and ultraviolet radiation (UV-IR). And, the (UV-IR), (GC-MS), and FTIR results confirm the presence of many organic compounds (Containing the N, S, and O atoms), which are responsible for inhibitor performance and absorption phenomena. Meanwhile, the electrochemical impedance results (EIS) indicate that the double layer capacity decreases and the corrosion resistance (Corrosion current density (icorr) from 0.128 to 0.009 mA/cm2) increases with the increase of the inhibitor concentration (The inhibition efficiency increased with increasing the inhibitor concentration from % 54.29 to the % 92.58 at (1–3 g/L). In addition, the corrosion current density decreases with the increase of the inhibitor concentration using the potentiodynamic polarization (PDP) test. However, the corrosion rate enhances with increasing the temperature. From the other hand, quantum chemical (QC) calculation and molecular dynamics (MD) simulation perform to investigate the theory of the adsorption mechanism. According to these studies, the adsorption of PPE on the aluminum 1050 alloy surface is agreement with the langmuir isotherm and as a result it is a mixed-type inhibitor. In final the SEM and AFM results show that the corrosion rate of the aluminum 1050 alloy surface is significantly reduced after the addition of the inhibitor to the corrosive environment. Furthermore, the contact angle image shows that the inhibited aluminum surface has a hydrophobic property in an aqueous solution. And, the QC calculation and MD simulation clarify well the thin layer formation due to the good adsorption of inhibitor (PPE) on the surface of aluminum 1050 alloy in the nitric acid solution, theoretically. It is concluded that PPE will inhibit the surface of aluminum against the corrosion agents in acidic environment and can use as a green inhibitor.

Multifacets of Fullerene-Metal Clusters: From Fundamental to Application.

ConspectusBuckminsterfullerene, C60, was discovered through a prominent mass peak containing 60 atoms produced from laser vaporization of graphite, driven by Kroto's interest in understanding the formation mechanisms of carbon-containing molecules in space. Inspired by the geodesic dome-shaped architecture designed by Richard Buckminster Fuller, after whom the particle was named, C60 was found to have a football-shaped structure comprising 20 hexagons and 12 pentagons. It sparked worldwide interest in understanding this new carbon allotrope, resulting in the awarding of the Noble Prize in Chemistry to Smalley, Kroto, and Curl in 1996.Intrinsically, C60 is an exceptional species because of its high stability and electron-accepting ability and its structural tunability by decorating or substituting either on its exterior surface or interior hollow cavity. For example, metal-decorated fullerene complexes have found important applications ranging from superconductivity, nanoscale electronic devices, and organic photovoltaic cells to catalysis and biomedicine. Compared to the large body of studies on atoms and molecules encapsulated by C60, studies on the exteriorly modified fullerenes, i.e., exohedral fullerenes, are scarcer. Surprisingly, to date, uncertainty exists about a fundamental question: what is the preferable exterior binding site of different kinds of single atoms on the C60 surface?In recent years, we have developed an experimental protocol to synthesize the desired fullerene-metal clusters and to record their infrared spectra via messenger-tagged infrared multiple photon dissociation spectroscopy. With complementary quantum chemical calculations and molecular dynamics simulations, we determined that the most probable binding site of a metal, specifically a vanadium cation, on C60 is above a pentagonal center in an η5 fashion. We explored the bonding nature between C60 and V+ and revealed that the high thermal stability of this cluster originates from large orbital and electrostatic interactions. Through comparing the measured infrared spectra of [C60-Metal]+ with the observational Spitzer data of several fullerene-rich planetary nebulae, we proposed that the complexes formed by fullerene and cosmically abundant metals, for example, iron, are promising carriers of astronomical unidentified spectroscopic features. This opens the door for a real consideration of Kroto's 30-year-old hypothesis that complexes involving cosmically abundant elements and C60 exhibit strong charge-transfer bands, similar to those of certain unidentified astrophysical spectroscopic features. We compiled a VibFullerene database and extracted a set of vibrational frequencies and intensities for fullerene derivatives to facilitate their potential detection by the James Webb Space Telescope. In addition, we showed that upon infrared irradiation C60V+ can efficiently catalyze water splitting to generate H2. This finding is attributed to the novel geometric-electronic effects of C60, acting as "hydrogen shuttle" and "electron sponge", which illustrates the important role of carbon-based supports in single-atom catalysts. Our work not only unveils the basic structures and bonding nature of fullerene-metal clusters but also elucidates their potential importance in astrophysics, astrochemistry, and catalysis, showing the multifaceted character of this class of clusters. More exciting and interesting aspects of the fullerene-metal clusters, such as ultrafast charge-transfer dynamics between fullerene and metal and their relevance to designing hybrid fullerene-metal junctions for electronic devices, are awaiting exploration.