Frontier Molecular Orbital Theory Research Articles

Going Beyond Woodward and Hoffmann's Electrocyclizations and Cycloadditions: Sigmatropic Rearrangements**

AbstractOn June 1, 1965, R. B. Woodward and Roald Hoffmann published their third communication in the Journal of the American Chemical Society in which they applied orbital symmetry control to explain the mechanism of a wide variety of valence isomerizations that they termed “sigmatropic reactions.” This publication reveals the research trajectory taken by Hoffmann from which this portion of the no‐mechanism problem was solved. Hoffmann used five different quantum chemical tools, all based on either extended Hückel theoretical calculations or frontier molecular orbital theory, in his research. Hoffmann′s laboratory notebooks and his three draft manuscripts along with Woodward′s four subsequent drafts have survived the past 59 years and provide an excellent window into the thinking and manuscript‐writing processes used by these Nobel laureates in February‐April 1965.

Comparison of gas-sensitive properties of Pb, Pd and Pt metal-doped Ti3C2X2 for aqueous zinc ion battery H2 gas

This work aims to provide early warning of uncontrolled reactions in aqueous zinc-ion batteries by timely and effectively detecting H2 gas. The large specific surface area and rich pore structure of Ti3C2X2 (X = F, O, and OH) make it a good gas-sensitive sensing material, and the gas-sensitive properties of the material can be improved by metal doping. Therefore, in this paper, the gas-sensitive response properties of Pb, Pd and Pt metal-doped Ti3C2X2 (M-Ti3C2X2) to H2 are compared based on density functional theory (DFT) calculations. The adsorption mechanism was analyzed by structure optimization, density of states, frontier molecular orbital theory and differential charge density, and the results were in high agreement. Doping of three metals, Pb, Pd and Pt, improved the adsorption capacity of Ti3C2X2 for H2 gas to different degrees. The simulation results show that the energy gap of Pb-Ti3C2(OH)2 adsorbed gas changes most obviously, and the maximum change value of energy gap (Eg) is 297.56 %. And Pt-Ti3C2F2 and Pt-Ti3C2O2 adsorbed H2 with large adsorption energies and large charge transfers indicating that they can be used as H2 removers. The energy gaps after the adsorption of H2 by M-Ti3C2O2 are 0.109 eV, 0.163 eV, and 0.082 eV, and the change of Eg is 24.77 %, 16.56 %, and 67.07 %, respectively. The change of Eg for the adsorption of H2 by Pt-Ti3C2O2 adsorbed H2 with a resistivity change of 67.07 %. This is caused by the irreversibility of adsorption due to too strong adsorption resulting in elongation of Pt-O bond length after adsorption. For the detection of H2, the properties of several doped materials were ranked as follows: Pb-Ti3C2(OH)2 > Pt-Ti3C2O2 > Pb-Ti3C2F2 > Pb-Ti3C2O2 > Pd-Ti3C2O2 > Pd-Ti3C2(OH)2 > Pt-Ti3C2F2 > Pt-Ti3C2(OH)2 > Pd-Ti3C2F2. In summary, it is shown that Ti3C2X2 doped with Pb, Pd and Pt metals is a potential H2 gas-sensitive material that can be a new material for online monitoring of fault gas content in aqueous zinc-metal energy storage batteries.

Preferred Electric Field Mechanism for Frustrated Lewis Pair Reactivity.

This study employs computational methods to investigate the mechanism of H2 activation by frustrated Lewis pair (FLP) species, including both intermolecular and intramolecular nitrothane/borane FLP systems. Previous studies have proposed two qualitative reactivity mechanism models to explain the facile cleavage of H2 by FLPs. The findings of this study support the electric field mechanism as the favorable pathway for H2 cleavage. Utilizing frontier molecular orbital theory and energy decomposition analysis, the study explores the electronic structure and nature of the reactions under an external electric field (EEF). Analysis using the activation strain model highlights the significant influence of geometrical deformation energies of FLPs on the activation barriers of H2 activation reactions. Computational results suggest that H2 activation by FLP molecules follows the electric field mechanism, indicating the potential of the FLP/EEF combination as an effective activator for inert molecules.

Adsorption behavior of temozolomide, carmustine, procarbazine, and lomustine anticancer drugs on zinc oxide nanocage: A DFT study

The adsorption behavior of zinc oxide (Zn12O12) nanocage toward delivering the temozolomide (TMZ), carmustine (CM), procarbazine (PR), and lomustine (LO) anticancer drugs was herein investigated utilizing the density functional theory (DFT) method. The emerging outcomes unveiled the potential efficiency of the Zn12O12 nanocage toward adsorbing the TMZ, CM, PR, and LO drugs and showed prominent negative values of binding energies (ΔEbind) up to −14.69 kcal.mol−1. Among the studied complexes, the Zn12O12-TMZ complex showed the most preferential ΔEbind values in the gas and water phases compared to other studied complexes with values up to −14.69 and −12.88 kcal.mol−1, respectively. The quantum theory of atoms in molecules announced the occurrence of the adsorption process between the Zn12O12 nanocage and anticancer drugs via polar covalent interactions and electrostatic interactions. Based on frontier molecular orbital theory affirmations, the electronic parameters of Zn12O12 nanocage changed preferentially upon adsorption of the studied drug within the most stable configurations. Moreover, the Zn12O12-drug complexes exhibited short recovery times for drug desorption from the nanocage. The results clearly confirmed that the Zn12O12 nanocage is an ideal candidate for the highly efficient development of anticancer TMZ, CM, PR, and LO drug carriers.

Theoretical evidence for a pH-dependent effect of carbonate on the degradation of sulfonamide antibiotics

Carbonate (CO32−/HCO3−) have a significant impact on advanced oxidation processes (AOPs) by consuming reactive free radicals such as HO• to generate CO3•-. However, research on the mechanisms and kinetics of CO3•- remains limited. This study investigates the degradation mechanism and kinetics of sulfonamide antibiotics (SAs) by CO3•- through theoretical calculations. The calculation results revealed that the effect of CO3•- on SAs degradation is pH-dependent due to the dissociable sulfonamide group (-SO2NH-) of SAs in the common water treatment pH range (3–8). The main reaction type of CO3•- with both neutral and anionic molecules of SAs is single electron transfer reaction. Frontier molecular orbital theory (FMO) illustrated that deprotonation of the sulfonamide group of SAs decreases the charge density on the heterocyclic ring, facilitating the electrophilic addition of CO3•-. The second-order rate constants of the neutral and anionic molecules of SAs with CO3•- were calculated as 7.57 × 101∼1.84 × 108 and 1.81 × 107∼7.94 × 109 M−1 s−1, respectively, resulting in an increase in the apparent reaction rate constants with pH. Stepwise multiple linear regression was employed to predict reactivity with anionic sulfonamide antibiotics (SAs−). Two models with outstanding prediction and stability were developed with coefficients of determination R2 of 0.660 and 0.681, respectively. The degradation kinetics simulation indicated that in the UV/H2O2 process in the presence of carbonate, the degradation rate of SAs increased with pH. Furthermore, the contribution of CO3•- to SMX degradation increased while that of HO• decreased. This study highlights the contribution of carbonates to the micropollutant degradation in the UV/H2O2 process as the model, providing theoretical insights into the development of carbonate-based AOPs.

A frugal machine-intelligent paper sensor for quantification of glucose through standalone desktop application: A computational and experimental approach

A paper-based electrochemical sensor utilizing MoS2 as sensing material is developed to quantitatively estimate glucose in a complex extracellular fluid matrix. The contribution of MoS2 as sensing material is substantiated in the context of density functional theory formalism. The molecular modelling of MoS2 and glucose interaction is elucidated through the theoretical estimation of non-covalent interactions and charge density difference plots. The charge transfer phenomenon during the oxidation of glucose molecule in electrochemical experiments is verified through electronic band structure analysis and frontier orbital theory. The electrochemical responses indicate that the sensor exhibits an average accuracy of nearly 96%, with a quantification limit of 100 nM. Furthermore, the chronoamperometric measurements highlight the superior sensitivity of the device in presence of various perturbing molecules. The obtained DPV responses were integrated with a robust machine learning-driven standalone app GluQuantify. This app precisely predicts the glucose concentrations in serum samples. The utilization of GluQuantify substantially elevates the overall accuracy of the sensing platform to 99% and automates the detection process. The application also enhances the resolution of the sensor to 0.01 µM, which mitigates the sensor resolution-related issues in manual estimation.

Synergy of pore confinement and co-catalytic effects in Peroxymonosulfate activation for persistent and selective removal of contaminants

The activation of peroxymonosulfate (PMS) through nanoconfinement and co-catalytic effects has demonstrated considerable promise in environmental remediation. Nevertheless, the attainment of persistent efficiency and specificity for pollutant degradation remains a formidable obstacle. Herein, we proposed a solvent-free molten approach to convert a mixture of zeolitic imidazolate frameworks (ZIFs) and MoS2 into 3D integrated cobalt-molybdenum bimetallic nitrogen-doped porous carbon foam with catalytic/co-catalytic performance (MC@NCF). The integrated materials exhibited exceptional efficiency in degrading contaminants based on the synergy of pore confinement and co-catalytic effects, achieving almost 100 % tetracycline degradation in 10 min with a k-value as high as 112.44 min−1·M−1, which was superior to the existing catalysts reported so far. The experimental findings revealed that the structural adjustment of MC@NCF significant accelerated the mass transfer through the formation of interfacial Mo-S/O-Co and Mo-N-Co/C bonds electron-tuning bridges between pore-confined micro-units, leading to the increased singlet oxygen (1O2) yield. Therefore, the MC@NCF exhibited more remarkable stability without interference from coexisting inorganic ions and cations, humic acid, and water matrices. Moreover, a flow-through nanoreactor was constructed and acquired efficient reactivity with negligible biotoxicity, and easy nanocatalyst recycling after continuous operation. The possible reactivity mechanism was identified by Frontier molecular orbital theory HOMO-LUMO, Fukui function, LC-MS, EPR, in-situ ATR-FTIR, and Raman analyses. Our results will guide integrated “catalytic/co-catalytic” nanoconfined MOF derivatives design to further enhance deep water purification technology.

Degradation of Diclofenac by Bisulfite Coupled with Iron and Manganous Ions: Dual Mechanism, DFT-Assisted Pathway Studies, and Toxicity Assessment

Diclofenac (DCF) is often detected in diverse aquatic bodies, and ineffective management can lead to detrimental effects on human health and ecosystems. In this study, degradation of DCF by Fe(III) and Mn(II) activating bisulfite (BS) was investigated. In the Fe(III)/Mn(II)/BS system, 93.4% DCF was degraded at 200 μM BS within 120 s, and additional research on 1000 μM BS achieved 88.4% degradation efficacy. Moreover, kinetics fitting of DCF degradation with the different BS concentrations was studied to find the two highest reaction rates (200 and 1000 μM, kobs = 0.0297 and 0.0317 s−1, respectively). Whereafter, SO4•− and Mn(III) were identified as the main active species at these two concentrations, respectively. Density functional theory (DFT) calculations, molecular frontier orbital theory, and surface electrostatic potential (ESP) forecast electrophilic attack sites. DCF degradation pathways by radical and non-radical ways were proposed by attack site prediction and thirteen intermediates identified by UPLC-QTOF-MS. ECOSAR software 2.2 was used for toxicity assessment. This work studied DCF degradation by the Fe(III)/Mn(II)/BS process in the presence of different concentrations of BS, providing a new insight into water purification.

Understanding the Adsorption Mechanism of BTPA, DEPA, and DPPA in the Separation of Malachite from Calcite and Quartz: DFT and Experimental Studies

The relationship between the structure of bis (2,4,4-trimethylpentyl) phosphinic acid (BTPA), diethyl phosphinic acid (DEPA), and diphenyl phosphinic acid (DPPA) on the flotation performance of malachite was investigated. Through a series of flotation experiments, density functional theory (DFT) calculations, and surface analysis methods, we aimed to deeply understand the microscopic mechanism of the interactions between these collectors and the malachite surface. The experimental results showed that BTPA exhibited excellent selectivity and flotation performance for malachite in the pH range of 5.0–11.0, significantly better than DEPA and DPPA. Surface analysis evidence from X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) further confirmed the chemical adsorption characteristics of BTPA on the malachite surface. DFT calculations revealed that the adsorption capacity of BTPA on the malachite surface exceeds that of DEPA and DPPA. Electron transfer analysis, especially through frontier molecular orbital theory, differential charge density, PDOS, and COHP analysis, indicated that the charge transfer process from the s orbitals of oxygen atoms in the collectors to the d orbitals of copper atoms on the mineral surface is the decisive factor for the adsorption strength.

Adsorption of SF6 decomposition gases (SO2 and SOF2) onto pristine and transition metal modified WSe2 monolayers: A systematic DFT study

The properties of SF6 characteristic decomposition products (SO2 and SOF2) adsorbed on intrinsic and transition metal atom modified WSe2 monolayers were studied based on the first principles. The adsorption structure, adsorption energy, electron transfer, density of states, electron differential density, work function, and desorption properties are comprehensively discussed. In addition, the charge transfer in the adsorption system was qualitatively analyzed by using the frontier molecular orbital theory and energy band. The results show that the pristine WSe2 monolayer has poor sensing performance for SO2 and SOF2. Effective modification methods can significantly increase the adsorption activity of the monolayer surface. The modification methods of transition metal atom adsorption and doping are discussed respectively. The modified monolayer all exhibit good sensing properties compared to the pristine monolayer due to the significant electronic hybridization between the impurity atoms and the gas molecules. Finally, the recovery response time of gas molecules from transition metal atom modified WSe2 monolayer is evaluated to evaluate its potential application in the detection and removal of fault gases in SF6 insulation equipment. Our work is not only important for predicting novel transition metal sulfide sensing materials, but also provides theoretical guidance for further developing WSe2-based sensors and scavengers for environmental monitoring applications.

Water-flow driven activation flexible PANI/β-PVDF piezoelectric spheres with enhanced piezoelectric properties for efficient degradation of organic pollutants

The conductive polymer polyaniline was introduced into poly(vinylidene fluoride) to improve its piezoelectric β phase content and conductivity, and a novel polyaniline/β-poly(vinylidene fluoride) (PANI/β-PVDF) piezoelectric spheres was prepared successfully for the water-flow driven piezocatalytic degradation of levofloxacin. PANI/β-PVDF piezoelectric spheres showed excellent piezocatalytic performance, and the degradation efficiency of levofloxacin reached 98.1 % within 30 min. It was worthing note that the EE/O value of the water-flow driven piezocatalytic system was only 6.57 % of that of the ultrasonic driven system. Based on the frontier orbital theory and Liquid chromatography-mass spectrometry, the possible piezocatalytic degradation pathways of levofloxacin were deduced. The results of toxicity migration evaluation during reaction showed that the acute toxicity and developmental toxicity of levofloxacin were significantly reduced. The piezocatalytic degradation of levofloxacin by PANI/β-PVDF piezoelectric spheres is triggered by the water-flow, which provides a new idea for the sustainable development of high efficiency and low consumption treatment of antibiotic wastewater.

Synergistic catalysis by Fe-oxide-biochar modified with WS2/PMS system for the removal of metformin

Metformin (MET) is frequently detected in aquatic environments, with its presence posing potential risks to flora and fauna. To enhance the redox cycling efficiency of Fe2+/Fe3+ in the Fenton reaction, a catalyst WSF@BC was synthesized by innovatively loading WS2 and iron oxides onto reed biochar to construct a novel non-homogeneous Fenton-like system for the degradation of MET in wastewater. This study investigated various parameters such as initial pH, peroxymonosulfate dosage, and catalyst dosage to determine their effects on the degradation efficiency. The results indicated that MET was degraded by 85.1 % within 30 min. The synergistic effect of WS2 and FeOx distinctly improved the removal efficiency of MET in this system, whereby SO4− dominated the rapid degradation of MET, as demonstrated by radical quenching experiments, electron paramagnetic resonance spectrometry (EPR) studies, and X-ray photoelectron spectroscopy (XPS) analysis. Frontier orbital theory calculations and intermediate product analyses revealed that the main reaction sites for MET degradation were CN and CN, resulting in reduced toxicity of degradation products. Three potential degradation pathways of MET via denitrification, amino oxidation, and hydroxylation were proposed by theoretical predictions and LC-MS/MS analysis. Additionally, characterization and recycling outcomes demonstrated excellent stability and reusability of the catalyst. This research highlights the significant application value of novel non-homogeneous catalysts for MET degradation in Fenton-like systems and provides theoretical support for achieving complete mineralization of MET.

Experimental and theoretical studies on the compatibility of DNTF and typical hydrocarbon polymer binders.

3,4-bis(3-nitrofurazan-4-yl) furoxan (DNTF) is one of the third-generation energetic compounds with excellent comprehensive properties, which can be added to polymer bonded explosive (PBX) to improve energy levels and regulate sensitivity, so the compatibility of DNTF with other components in PBX, especially the binder, is the first question. Herein, two typical hydrocarbon polymers commonly used in PBX, which are hydroxyl-terminated polybutadiene (HTPB) and polyisobutylene (PIB), were selected as the binder, and the compatibility of HTPB and PIB with DNTF was investigated by differential scanning calorimetry (DSC), the vacuum stability test (VST), and in situ infrared spectroscopy (in situ IR). The results of compatibility experiments were verified by using the binding energy and solubility parameter criteria in molecular dynamics (MD). Experimental and MD simulation results showed that DNTF could be compatible with PIB but incompatible with HTPB. The frontier molecular orbital theory in quantum chemistry (QC) was adopted to explore the frontier orbital electron distribution and energy levels of DNTF/HTPB and DNTF/PIB composite systems to better understand the microscopic compatibility mechanism. The compatibility results of the two composite systems were explained from the perspective of electron transfer. All these can deduce that a hydrocarbon polymer binder with a saturated carbon-hydrogen bond at the end of the molecular chain has good compatibility with DNTF, compared with a hydroxyl group, which has bad compatibility with DNTF.

Corrosion Inhibition Performance of Brachystegia eurycoma Leaf Extract on Mild Steel in Acid Media

The aim of this work is to investigate the corrosion inhibition of B. eurycoma leaves extract as a natural inhibitor for mild steel corrosion in 3 M H2SO4 solution. The corrosion inhibitory activity was analyzed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The surface roughness and its properties through scanning electron microscopy (SEM). The obtained result from EIS divulges that the gradual increase in inhibitor concentration and time of immersion leads to progressive increase in inhibition efficiency. At the end of 8 hours immersion time and inhibitor concentration of 1000 mg/l the highest inhibition efficiency of (88%) was obtained. The potentiodynamic polarization results indicated that addition of B. eurycoma leaves extracts hindered the reaction rates of anodic and cathodic reactions thereby performing as mixed- type inhibitor. The corrosion current density also revealed that in the presence of B. eurycoma leaves extracts the value of corrosion density reduced considerably from 265.2 \(\mu\) A/cm2 for sample without inhibitor to 67.8 \(\mu\) A/cm2 for sample with inhibitor. Again, it was observed that in the presence B. eurycoma leaves extracts the mechanism of hydrogen (effervescence) evolution was unique whereas the anodic dissolution of iron mechanism experienced the impact of the inhibitor. SEM inspection revealed that the mild steel surface showed smoother and lower damage in the presence of inhibitor. Obvious correlations were found between corrosion inhibition efficiency and some quantum chemical parameters such as energy of highest occupied molecular orbital (EHOMO), energy of lowest unoccupied molecular orbital (ELUMO), energy gap (EL–H) and electronic density etc. The obtained results were further elucidated with frontier molecular orbital theory.

Synthesis of biomass‐derived ethyl levulinate from steam‐exploded corn straw

AbstractEthyl levulinate (EL) production from steam‐exploded corn straw (SCS) in a cascade of reaction using a Brønsted (B) acid and a Lewis (L) acid in ethanol was studied. The entangled structure of corn straw could be obviously damaged through steam explosion when the pressure was 1.5 MPa holding 10 min. The content of cellulose can be increased from 35.9% to 46.8%, and the contents of hemicellulose and lignin were changed from 16.7% to 8.8% and 22.6% to 27.5%, respectively. EL yield was significantly increased from 10.7 to 24.6 wt% under optimal reaction conditions (L/B = 1/20 [mol/mol], 205°C, 90 min, 1.8 g of SCS, 60 mL of ethanol). According to kinetic models, the activation energies for the main and side reactions were 56.8 and 110.5 kJ mol−1, respectively. It suggested that SCS was more easily to be converted to EL rather than other by‐products. The highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energy gaps (HOMO‐LUMO gaps) of cellobiose over the mixed acids in ethanol were significantly reduced with frontier molecular orbital (FMO) theory. This work provides an effective strategy for EL production from agricultural waste straws.

The mechanism of water decomposition on surface of aluminum and gallium alloy during the hydrogen production process: A DFT study

The efficient hydrogen-production through the Aluminum-water reaction has become a prominent subject of interest. The impediment encountered in the reaction can be effectively alleviated by Aluminum-based alloy. In this study, density functional theory (DFT) was utilized to explore the mechanism of water decomposition stage on the surface of aluminum and gallium alloy (AGA). Through surface reaction calculations of 12 stable AGA configurations, it was gradually revealed that the optimal alloy ratio was gallium-to-aluminum at 3.5:1. Analysis of the density of states (DOS) indicated that the presence of gallium amplified the activity of surface aluminum. Moreover, frontier orbital theory and charge density maps confirmed that, due to the weak interaction between Ga and ions, the presence of H2 inhibited Ga passivation, thereby enhancing the reactivity of AGA. This paper provided valuable insights into the surface reaction mechanisms of AGA using DFT, offering theoretical support for hydrogen production processes.

Quantum chemistry calculation-aided discovery of potent small-molecule mimics of glutathione peroxidases for the treatment of cisplatin-induced hearing loss

Hearing loss (HL) is a health burden that seriously affects the quality of life of cancer patients receiving platinum-based chemotherapy, and few FDA-approved treatment specifically targets this condition. The main mechanisms that contribute to cisplatin-induced hearing loss are oxidative stress and subsequent cell death, including ferroptosis revealed by us as a new mechanism recently. In this study, we employed the frontier molecular orbital (FMO) theory approach as a convenient prediction method for the glutathione peroxidase (GPx)-like activity of isoselenazolones and discovered new isoselenazolones with great GPx-like activity. Notably, compound 19 exhibited significant protective effects against cisplatin-induced hair cell (HC) damage in vitro and in vivo and effectively reverses cisplatin-induced hearing loss through oral administration. Further investigations revealed that this compound effectively alleviated hair cell oxidative stress, apoptosis and ferroptosis. This research highlights the potential of GPx mimics as a therapeutic strategy against cisplatin-induced hearing loss. The application of quantum chemistry (QC) calculations in the study of GPx mimics sheds light on the development of new, innovative treatments for hearing loss.

Experimental testing and mechanism investigation of amine-functionalized layered vermiculite for CO2 capture

Solid amine adsorbents have attracted significant attention due to their low energy consumption, high selectivity, and environmental friendliness, positioning them as the most promising technology for CO2 capture. However, current adsorbent carrier materials commonly encounter challenges such as expensive costs and inadequate stability. In this study, acid-activated expanded vermiculite carrier (AEV) with a large pore volume and hierarchical pore structure was prepared. Subsequently, a series of functionalized polyethyleneimine (PEI) adsorbents were synthesized and employed in CO2 capture experiments to investigate the impact of PEI loading and temperature on adsorption characteristics. The results showed that the acid-modified expanded vermiculite with a large pore volume structure significantly increased amine loading, while the layered structure network promoted amine dispersion. Under the conditions of 50 wt% PEI loading, the CO2 capture capacity of AEV reached 3.29 mmol/L at 75 ℃. Furthermore, density functional theory was utilized to calculate the adsorption energy and Gibbs free energy change of CO2 and polyethyleneimine molecules. The HOMO and LUMO distributions of CO2 molecules with different polyethyleneimine chains were determined using frontier orbital theory, combined with infrared spectroscopy results confirming the conversion of CO2 into carbamate. Additionally, AEV-PEI50 adsorbent exhibited good stability during 8 cycles of the adsorption process. The obtained results demonstrate that the utilization of layered mesoporous scaffolds offers notable benefits in terms of efficient CO2 capture.

Nickel(I)-catalysed multicomponent reductive hydrocarbonylation of alkenes: A theoretical study of mechanism, regio-, enantio-, and chemoselectivity

In the present study, theoretical calculations were performed to gain a deeper understanding of the nickel-catalysed multicomponent reductive hydrocarbonylation of alkenes using ethyl chloroformate as the CO source and hydrosilane as the hydride source. The computations show Ni(I) species acts as the active catalyst entering the catalytic cycle. The calculated mechanism corroborates the experimental mechanistic proposals on the elementary steps. Nonetheless, the sequence of elementary steps and the oxidation state of the nickel center are different from the experimental proposal. The calculations reproduced quite well the experimentally observed regio- and enantioselectivity. The distortion/interaction analysis and frontier molecular orbital theory confirm that the interaction energy determines the regioselectivity. The high S-enantioselectivity arises from the stronger C–H/π interactions in the S-configuration compared to those in the R-type enantiomer. One of the biggest challenges faced by multicomponent reactions is competing side-reactions. To explore the reaction's chemoselectivity, we calculated the formation mechanisms of five potential by-products and analyzed the driving force behind the formation of the desired product.

Adsorption Properties of Dissolved Gas Molecules in Transformer Oil on the ReSe2 Monolayer: A DFT Study.

Based on density functional theory, the adsorption behavior of seven typical dissolved gas molecules (CO, CO2, H2, CH4, C2H2, C2H4, and C2H6) and H2O molecule on the ReSe2 monolayer was systematically investigated. The interactions between the ReSe2 monolayer and eight gas molecules were investigated by calculating the adsorption energies, charge transfer, density of states (DOS), and deformation charge density (DCD) for eight different adsorption systems. The gas sensitivity of the ReSe2 monolayer toward these gases was studied using frontier molecular orbital theory and work function analysis. The results demonstrate that compared to other gas molecules, the ReSe2 monolayer exhibits a stronger interaction with CO with an adsorption energy of -1.49 eV. It also displays excellent sensitivity and selectivity toward CO making it a promising candidate for CO gas sensing applications. We aspire that this research will offer theoretical guidance for the development of ReSe2-based gas sensors and contribute to state monitoring technology in oil-immersed power equipment.