Lowest Unoccupied Molecular Orbital Energy Research Articles

Insights into the structural, electronic, quantum chemical properties and molecular docking studies on novel NAMPT inhibitor molecule

This research paper presents a comprehensive study on a novel NAMPT (Nicotinamide phosphoribosyl transferase) inhibitor molecule, N- [4- [(4R)-1,4-dimethyl-6-oxidanylidene-4,5-dihydropyridazin-3-yl] phenyl]-5,7-dihydropyrrolo [3,4-b] pyridine-6-carboxamide], with the potential applications in cancer therapy. We performed quantum chemical calculations with DFT and topological investigations on the molecule to understand its electronic properties and chemical behaviour. The study covers basic molecular properties, molecular planarity and various electronic properties, including the HOMO (Highest Occupied Molecular Orbital), LUMO (Lowest Unoccupied Molecular Orbital) energy levels, the energy gap of 4.09 eV, ionization potential, electron affinity, electronegativity, chemical potential, chemical hardness, chemical softness, electrophilicity index, Mulliken atomic charges, Laplacian bond order, and ESP (Electrostatic Potential) properties. Moreover, we studied the nature of bonding and interactions within the molecule using ELF (Electron Localization Function), LOL (Localized Orbital Locator), RDG (Reduced Density Gradient), and NCI (Non-covalent Interaction). An analysis of the title molecule's molecular thermodynamic properties demonstrates its intrinsic stability under thermal and quantum effects. Molecular docking studies were also performed to reveal how the molecule interacts with its target protein, exhibiting a strong binding affinity for NAMPT target proteins (7PPF and 5WI0), which could help develop future cancer drugs. This multifaceted investigation provides a detailed understanding of the molecular structure and interactions of the molecule with NAMPT protein, potentially paving the way for its potential use as a cancer therapy.

A sulfonated polyimide containing flexible aliphatic segments with high chemical stability for vanadium redox flow battery application

To improve sulfonated polyimide (SPI) chemical stability, the SPI containing flexible aliphatic segments is successfully designed and synthesized. The highest occupied molecular orbital (HOMO) energy, lowest unoccupied molecular orbital (LUMO) energy and their energy gaps (HOMO-LUMO gap (ΔE)) can quantitatively compare the molecular reactivity, which are calculated and used to compare firstly in the SPIs for vanadium redox flow battery (VRFB) application. Furthermore, the natural bond orbital (NBO) charge of SPIs is also used to calculate and compare, respectively. Theoretical calculation shows SPI(DAD) has higher chemical stability. Obtained by experimental results that the retention time in water of SPI(DAD)-60 membrane is 23.58 h at 80 °C, which is nearly four times than conventional SPI under the same conditions. The SPI(DAD)-60 membrane at a current density of 100 mA cm−2 shows higher columbic efficiency (CE: 96.83%), and energy efficiency (EE: 79.47%) than that of N212 membrane (CE: 93.14%, EE: 74.13%). Besides, the SPI(DAD)-60 membrane has 479.1 mA h more charging capacity after 100 cycles compared to N212 membrane. The theoretical calculation of the LUMO energy, HOMO-LUMO gap may be a potential tool that is used to analyze and evaluate the chemical stability of membranes for VRFB application.

Combining large-scale investigation and quantum chemical calculation of pharmaceuticals: Spatiotemporal patterns of occurrence and structural insights into removal

This study investigated the spatiotemporal distribution of 17 pharmaceuticals in wastewater treatment plants (WWTPs) from 17 provinces across China, and explored structural insights into their removal in full-scale wastewater treatment processes by quantum chemistry. Briefly, 10 pharmaceuticals were detected in above 85 % of samples, of which ibuprofen and sulfamethoxazole dominated with concentrations up to the μg/L level. Seasonally, concentrations of psychoactive drugs (PDs) were 1.3–2.6 times higher in summer than in other seasons. Spatially, higher average concentrations were detected in northern WWTPs, and regions with similar economic levels exhibited similar contamination patterns. Pharmaceutical removal in WWTPs ranged from 41.4 % (carbamazepine) to 87.2 % (sulfamethizole), with the secondary treatment segment, especially aerobic treatment units, maintaining an important position. Molecular structural mechanisms behind these removal performances were further revealed. Firstly, we demonstrated a significant association of pharmaceutical overall removal with electrophilicity index (ωcubic) as well as the lowest unoccupied molecular orbital energy (ELUMO). Highly electrophilic pharmaceuticals may persist in WWTPs and their sensitivity to electron exchange reactions accounted for the discrepant removal. In terms of treatment segments, pharmaceuticals with reaction sites masked in molecular structure, such as ibuprofen and venlafaxine, showed a propensity for tertiary treatment suitability. Furthermore, enzymes of aerobic units exhibited excellent docking affinity to pharmaceutical molecules with an average affinity of −7.2 kcal/mol, and hydrogen-bond interactions played an important factor in promoting biodegradation. Our results emphasize the necessity of assessing pharmaceutical contamination on a larger spatiotemporal scale. Moreover, the structural insights into removal phenomena offer scientific molecular-level justification for the design and optimization of pharmaceutical treatment technologies in WWTPs.

Molecular understanding of electron donor influences in dye-sensitized solar cells of novel series-based D-A’-(π-A)2

The efficiency of the designed dye-sensitized solar cells (DSSCs) containing phenothiazine phenoxazine, and 5,10-dimethylphenazine as donors and triazine, phenyl with D-A’-(π-A)2 architecture has been examined utilizing Time-dependent (TD-DFT) and Density Functional Theory (DFT) techniques. The geometrical structures, electrical characteristics, absorption, and photovoltaic characteristics were studied using these techniques. Additionally, the computed findings show that various layouts can alter the HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital) energy levels and reduce the energy gap between 1.63 and 2.30 eV. The absorption undergoes a redshift displacement. These bands are between 300 and 400 nm. This work aims at calculating the structural geometries and the electronic and optical properties of the designed dyes. In order to shed light on the bridging influence on geometric and TD-BHandH/6-31G(d) for optoelectronic properties, the density functional theory (DFT) and time-dependent TD-DFT at the B3LYP/6-31G(d) level were examined. Additionally, the complex [email protected] cluster's binding energies have been investigated.

Corrosion inhibition efficiency of quinoxalines based on electronic structure and quantum computational analysis

Based on the quantum chemical parameters obtained from density functional theory (DFT) with 6-311++ G (d, p) basis set at B3LYP level, a theoretical study of the corrosion inhibition effectiveness of 1-[4-acetyl-2-(4-chlorophenyl) quinoxalin-1(4H)-yl] acetone (A), 2-(4-(2-ethoxy-2-oxoethyl)-2-p-tolylquinoxalin-1(4H)-yl) acetate (B) and 2-(4-methylphenyl)-1,4-dihydroquinoxaline (C) were evaluated. A number of quantum chemical parameters were determined to assess the array of molecules selected, including lowest unoccupied molecular orbital energy, highest occupied molecular orbital energy, hardness, ionization potential, the electronegativity, dipole moment, the fraction of electrons transferred to the metal surface, total energy and softness. Experiments were found to be in agreement with theoretical data.

Elucidation of benzene sulfonamide derivative binding at a novel interprotomer pocket of wild type and mutants of coxsackievirus B3 viral capsid using molecular dynamics simulations and density functional theory

Coxsackievirus B3 (CVB3), a serotype of enterovirus B, causes hand, foot, and mouth disease; pericarditis; and myocarditis. A benzene sulfonamide derivative is reported to have inhibitory activity against wild-type (WT) and eight mutants of the viral capsid of CVB3. Furthermore, the crystal structure of the complex formed between WT viral capsid of CVB3 and the derivative revealed binding at a novel druggable interprotomer pocket. We investigated how the compound could be a potent inhibitor of both WT and some mutants of CVB3 by determining binding to the viral capsid and the interaction energy with the binding pocket based on molecular dynamics simulations and density functional theory. We found that hydrogen bonds, pi–pi interactions, and electrostatic interactions are the key interactions with a protomer unit of CVB3 viral capsid. The residual interaction energy determined using density functional theory revealed key binding with VP1:Arg234 and a residue in the nearby VP1 unit (VP1’:Arg219). These results explain why the compound is still a potent inhibitor against eight mutants. Moreover, the decreased inhibitory activity for some mutants could be explained by the calculated binding energy and the highest occupied molecular orbital and lowest unoccupied molecular orbital energy. The results will be helpful for the development of drugs resistant to CVB3.

Data-Driven Insight into the Reductive Stability of Ion-Solvent Complexes in Lithium Battery Electrolytes.

Lithium (Li) metal batteries (LMBs) are regarded as one of the most promising energy storage systems due to their ultrahigh theoretical energy density. However, the high reactivity of the Li anodes leads to the decomposition of the electrolytes, presenting a huge impediment to the practical application of LMBs. The routine trial-and-error methods are inefficient in designing highly stable solvent molecules for the Li metal anode. Herein, a data-driven approach is proposed to probe the origin of the reductive stability of solvents and accelerate the molecular design for advanced electrolytes. A large database of potential solvent molecules is first constructed using a graph theory-based algorithm and then comprehensively investigated by both first-principles calculations and machine learning (ML) methods. The reductive stability of 99% of the electrolytes decreases under the dominance of ion-solvent complexes, according to the analysis of the lowest unoccupied molecular orbital (LUMO). The LUMO energy level is related to the binding energy, bond length, and orbital ratio factors. An interpretable ML method based on Shapley additive explanations identifies the dipole moment and molecular radius as the most critical descriptors affecting the reductive stability of coordinated solvents. This work not only affords fruitful data-driven insight into the ion-solvent chemistry but also unveils the critical molecular descriptors in regulating the solvent's reductive stability, which accelerates the rational design of advanced electrolyte molecules for next-generation Li batteries.

Green synthesis of novel bis structure of (Carbamothioyl) oxalamide derivatives as corrosion inhibitors for copper in 3.5% NaCl; experimental and theoretical investigation

Carbamothiol oxalamide derivatives as new compounds are synthesized and named N1, N2-bis (2- ((2-hydroxyethyl) amino) ethanethiol) oxalamide (bis 1), and N1, N2- bis(2-(bis(2-hydroxyethyl) amino) ethanethiol) oxalamide (bis 2). The noteworthy highlights of this method are eco-friendly, excellent yields, economic, catalyst-free, and solvent-free. Their chemical structures are clarified and validated using elemental analysis and spectroscopic techniques such as Fourier-transform infrared spectroscopy (IR), 1H, and 13C- nuclear magnetic resonance. Then, Weight loss (WL), electrochemical impedance spectroscopic (EIS), and potentiodynamic polarization (PDP) techniques are applied to examine the inhibition impact of these new derivatives on copper in 3.5% NaCl. The density functional theory is used to apply theoretical computations. The results of the experiments indicate that these substances are effective corrosion inhibitors, and their inhibition efficiencies rise with concentration. The bis 2 compound having four OH groups, give the highest efficiency compared to bis 1. There was good agreement on the outcomes of the various procedures. Utilizing 0.01 M of bis 2 to examine the surface under the SEM reveals the existence of an adsorbed layer. All organic molecules, including nitrogen, sulfur, and oxygen, block the metal surface as shown by the electronic parameters highest occupied and lowest unoccupied molecular orbital energy, and ΔEg. The results from theoretical calculations and those from experimental measurements correspond well.

First Principle Study on Structural, Electronic, Vibrational Properties and Molecular Docking Study of Tyramine

First principle study of cyclic compound has a great interest because their products are very much useful in biological and clinical applications. In this work, Density functional theory (DFT) and Time dependent DFT calculations have been performed to study structural, electronic and vibrational properties of Tyramine (a neuromodulator) at B3LYP/3-21G level employing Gaussian 09 software. All the theoretical calculations were carried out to study the equilibrium geometries, vibrational spectra, molecular electrostatic potential (MEP), highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and UV-Vis spectra of the title compound. Also, the molecular docking analysis of Tyramine against two different proteins (Trace amine-associated receptor 1 and Dopamine D2 receptor) was carried out using AutoDock Vina. The scaled values of calculated vibrational frequencies were used for vibrational assignments on the basis of the potential energy distribution (PED). The structure activity relation has been interpreted by mapping MEP and Time dependent DFT method has been adopted to elucidate electronic properties. Graphical representation of frontier molecular orbital for both gaseous and solvent phase provides valuable insight into the nature of reactivity, stability and some of the structural and physical properties of the title molecule. Also, the calculated HOMO and LUMO energy values show that the charge transfer occurs within the molecule. Further, the title molecule shows good potentiality for binding against Trace amine-associated receptor 1 (1TQN) with binding affinity -6 kcal/mol The binding site of the Tyramine is found to be amine (NH2) group.

New Medium-Bandgap Nonfused Ring Guest Acceptor with a Higher-Lying LUMO Level Enables High-Performance Ternary Organic Solar Cells.

Adding another constituent into a binary system, known as a ternary strategy, represents a simple and effective approach to boosting the power conversion efficiency (PCE) of organic solar cells (OSCs). Herein, we have prepared a new nonfused ring small-molecule acceptor with a medium bandgap, named DFTQA-2FIC, which possesses a high-lying lowest unoccupied molecular orbital energy level and a strong intramolecular charge-transfer effect. We elaborately utilized it as a third component in a typical PM6:Y6 blend to obtain high-performance ternary OSCs. The resulting ternary blend film exhibited superior and balanced hole/electron mobility, enhanced favorable aggregation morphology, and reduced charge carrier recombination. Consequently, an optimized ternary OSC presented a distinctly increased PCE of 17.29%, accompanied by synchronous enhancements in crucial parameters, representing a 7.46% improvement over the binary OSC based on PM6:Y6 with a PCE of 16.09%. This study highlights that incorporating DFTQA-2FIC as a third component in a binary system is suitable for optimizing photovoltaic performance.

Characterizing the structural and physicochemical properties of medicinal plants as a proposal for treating of viral malady

Regarding coronavirus disease (COVID-19) pandemic, this research article wants to study some herbals as the probable therapy for this disease. Cinnamon leaves, curcuma longa (turmeric), ginger, mentha pulegium (pennyroyal), rosemary, salvia divinorum and thyme including some principal chemical compounds of cynnamil, curcumin, gingerol, pulegone, rosmarinic acid, salvinorina A and thymol, respectively, as a probable anti COVID-19 receptor have been selected. The possible roles of these medicinal plants in COVID-19 treatment have been carried out through quantum sensing methods. Formation of hydrogen bonding between principal substances selected in COVID-19 natural drugs bound to Tyrosine-Methionine-Histidine (Tyr-Met-His) or (TMH) (the database amino acids fragment) as the active area of the COVID-19 protein has been evaluated. In fact, it has been exhibited the role of oxygen, nitrogen, and hydrogen atoms in the active sites of these anti-virus medications towards hydrogen bonding in the active site if “TMH” protein. The physical and chemical attributes of nuclear magnetic resonance, vibrational frequency, the highest occupied molecular orbital energy and the lowest unoccupied molecular orbital energy, partial charges and spin density and have been accomplished using density functional theory (DFT) method and 6-311+G (2d,p) basis set by Gaussian 16 revision C.01 program toward the industry of drug design. This research has exhibited that there is a relative agreement among the results that these medicinal plants could be efficient against COVID-19 symptoms.

Density Functional Theory-Based Predictions and Experimental Evaluations of Ferrocene Derivatives Considered as Mediator for Anodic Catalysts of Glucose and Oxygen Enzymatic Biofuel Cells

The redox potential (ERedox) of a ferrocene (Fc) derivative differs, depending on its functional group. In this study, the various Fc derivatives are considered as mediators of anodic catalysts to promote glucose oxidation reaction (GOR) in glucose/oxygen enzymatic biofuel cells (EBFCs). Initially, their lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energies are calculated using density functional theory to predict their ERedox pattern. According to the calculations, the LUMO and HOMO energies of Fc derivatives combined with electron-donating groups (EDGs) are higher than those of Fc derivatives combined with electron-withdrawing groups (EWGs), including the results that Fc(NH2) has the highest molecular orbital (MO), while Fc(CHO) has the lowest. To verify the prediction for ERedox pattern, electrochemical evaluations are conducted. When glucose is provided, the onset potential (EOnset) of GOR is measured, while the ERedox of Fc derivatives and EOnset of GOR are linearly proportional to each other ( R 2 = 0.98 ) and DFT calculations. As the energies increase, the above two potentials are shifted more negatively. More specifically, the ERedox of Fc(NH2) and EOnset of GOR show the most negative values at (−0.112 and −0.17) V, respectively, while the ERedox of Fc(CHO) and EOnset of GOR show the most positive values at (0.496 and 0.40) V, respectively. Then, when this correlation is adopted for EBFCs, EBFCs using Fc(NH2) combined with EDG show 3.7 times higher maximum power density than those using Fc(COOH), as representatives combined with EWG. Based on that, it is well established how DFT and electrochemical evaluations should be used to design anodic catalysts including Fc derivatives as mediators for GOR.

Novel Mechanism-Based Descriptors for Extreme Ultraviolet-Induced Photoacid Generation: Key Factors Affecting Extreme Ultraviolet Sensitivity.

Predicting photolithography performance in silico for a given materials combination is essential for developing better patterning processes. However, it is still an extremely daunting task because of the entangled chemistry with multiple reactions among many material components. Herein, we investigated the EUV-induced photochemical reaction mechanism of a model photoacid generator (PAG), triphenylsulfonium cation, using atomiC-Scale materials modeling to elucidate that the acid generation yield strongly depends on two main factors: the lowest unoccupied molecular orbital (LUMO) of PAG cation associated with the electron-trap efficiency 'before C-S bond dissociation' and the overall oxidation energy change of rearranged PAG associated with the proton-generation efficiency 'after C-S bond dissociation'. Furthermore, by considering stepwise reactions accordingly, we developed a two-parameter-based prediction model predicting the exposure dose of the resist, which outperformed the traditional LUMO-based prediction model. Our model suggests that one should not focus only on the LUMO energies but also on the energy change during the rearrangement process of the activated triphenylsulfonium (TPS) species. We also believe that the model is well suited for computational materials screening and/or inverse design of novel PAG materials with high lithographic performances.

Tailoring the Weight of Surface and Intralayer Edge States to Control LUMO Energies.

The energies of the frontier molecular orbitals determine the optoelectronic properties in organic films, which are crucial for their application, and strongly depend on the morphology and supramolecular structure. The impact of the latter two properties on the electronic energy levels relies primarily on nearest-neighbor interactions, which are difficult to study due to their nanoscale nature and heterogeneity. Here,an automated method is presented for fabricating thin films with a tailored ratio of surface to bulk sites and a controlled extension of domain edges, both of which are used to control nearest-neighbor interactions. This method uses a Langmuir-Schaefer-type rolling transfer of Langmuir layers (rtLL) to minimize flow during the deposition of rigid Langmuir layers composed of π-conjugated molecules. Using UV-vis absorption spectroscopy, atomic force microscopy, and transmission electron microscopy, it is shown that the rtLL method advances the deposition of multi-Langmuir layers and enables the production of films with defined morphology. The variation in nearest-neighbor interactions is thus achieved and the resulting systematically tuned lowest unoccupied molecular orbital (LUMO) energies (determined via square-wave voltammetry) enable the establishment of a model that functionally relates the LUMO energies to a morphological descriptor, allowing for the prediction of the range of accessible LUMO energies.

Dynamic Metastable Characteristics of Carbon Cages Embedded with Er2C2.

Novel endohedral metallofullerenes (EMFs), namely, Er2C2@C2v(5)-C80, Er2C2@Cs(6)-C82, Er2C2@Cs(15)-C84, Er2C2@C2v(9)-C86, Er2C2@Cs(15)-C86, and Er2C2@Cs(32)-C88, had been experimentally synthesized, and the unique structures and many fascinating properties had also been widely explored. Nevertheless, the position of the Er atoms inside the cage shows a severe disorder within the stable EMF monomer, which is difficult to understand and explain from the experimental point of view. In this work, based on the density functional theoretical calculations, the Er2C2@Cs(6)-C82 has 73 directional isomers and 2 Er atoms that are far beyond from Er-Er single bonding and tend to be close to the cage side (marked as "shell"), and the core (Er2C2 units) takes on a butterfly shape as generally revealed. The energy difference between any two of the isomers is in the range of 0.05 to 25.6 kcal/mol, indicating a relatively easy thermodynamic transition between the isomers. The other five Er carbide cluster EMFs (Er2C2@C2v(5)-C80, Er2C2@Cs(15)-C84, Er2C2@C2v(9)-C86, Er2C2@Cs(15)-C86, and Er2C2@Cs(32)-C88) are also studied in the same way, and 30, 37, 39, and 43 most stable Er-oriented sites inside the cage, respectively, are obtained. In addition, the shape of the Er2C2 gradually changed from butterfly to linear. Moreover, the electronic structure and molecular orbital analyses show that it is easy for Er2C2@C80-88 to form a charge transfer state of [Er2C2]4+@[C80-88]4- via the dynamic core-shell coordination equilibrium. Er2C2 with a steep drop in chemical stability is restricted to forming varying degrees of metastable states in the shell, determined by the shell size, to ensure the overall stability. The lowest unoccupied molecular orbital energy level of these EMFs is increased by 0.5-1.1 eV compared with fullerenes C80-88, potentially providing favorable conditions for suitable energy level matching with EMF as an electron acceptor used in organic solar cell devices.

Significance of anchoring group design on light harvesting efficiency of dye-sensitized solar cells and non-linear optical response

Dye-sensitizers designed from coumarin backbone are widely utilized in solar light harvesting due to their versatile performance in dye-sensitized solar cells (DSSC). They are well-known as non-linear optical (NLO) materials. In this case study, we have designed coumarin-based sensitizers containing thiophene as a common spacer with the different acceptor-anchoring groups, ethyl-2-cyanoacrylate (SPDSSC 1) and 2-cyanoacrylic acid (SPDSSC 2). Density functional theory (DFT) and time-dependent- DFT (TD-DFT) computational calculations of these molecules predict superior light harvesting capability and NLO properties. The calculated HOMO–LUMO energy gap of these dyes showed an inverse relation with chemical potential and electrophilicity index and was directly related to hardness and hyperhardness. It was also seen β0 and γ and PCE follow a similar trend. Further, computations of sensitizers@TiO2 indicated sensitizers with ethyl-2-cyanoacrylate bonded with TiO2 cluster via unidentate linkage, whereas 2-cyanoacrylic acid containing sensitizer involved bidentate bonding with TiO2. Apart from this, sensitizers with 2-cyanoacrylic acid anchors showed much planer geometry. Also, the quantitative analysis of the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) and MEP plots showed that more electron clouds shifted to the TiO2 cluster in the sensitizer with 2-cyanoacrylic acid (SPDSSC 2) than ethyl-2-cyanoacrylate (SPDSSC 1). Further, both molecules were taken as sensitizers in the DSSC device. SPDSSC 2 showed higher power conversion efficiency than SPDSSC 1. Overall, results disclosed that sensitizers with ethyl-2-cyanoacrylate having two oxygen atoms in their anchoring part could bind with only carbonyl oxygen. And this monodentate binding of ethyl-2-cyanoacrylate with TiO2 leads to poor charge transfer in the semiconductor's conduction band, resulting in poor DSSC performance.

An effective strategy to design high-performance wide bandgap polymer donors for organic solar cells by increasing the backbone curvature

Although wide bandgap (WBG) polymer donors are widely used in non-fullerene organic solar cells (OSCs), only a few WBG polymers exhibited high power conversion efficiencies (PCEs). Developing WBG donors with ideal complementary absorption with narrow bandgap non-fullerene acceptors is critical to further improving the photovoltaic performance of OSCs. Here, we provide an effective strategy to widen the bandgap (Eg) of polymers by increasing the curvature of the polymer donor backbone structure and compare it with the fluorination strategy. Both experimental and theoretical results demonstrated that the fluorination strategy reduced the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of PBDT-DT2FBT with little effect on the Eg. In contrast, the polymer PBDT-DTfBT, with a large backbone curvature, exhibited a reduced HOMO energy level and a significantly increased LUMO energy level, resulting in a significant increase in the optical Eg of 0.19 eV. The PBDT-DTfBT-based device achieved a high PCE of 15.89%, which far exceeded the PCEs of the PBDT-DTBT (9.84%) and PBDT-DT2FBT-based devices (8.02%). This work could guide the design of high-performance WBG donors.

Mapping the frontier orbital energies of imidazolium-based cations using machine learning.

The knowledge of the frontier orbital, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), energies is vital for studying chemical and electrochemical stability of compounds, their corrosion inhibition potential, reactivity, etc. Density functional theory (DFT) calculations provide a direct route to estimate these energies either in the gas-phase or condensed phase. However, the application of DFT methods becomes computationally intensive when hundreds of thousands of compounds are to be screened. Such is the case when all the isomers for the 1-alkyl-3-alkylimidazolium cation [CnCmim]+ (n = 1-10, m = 1-10) are considered. Enumerating the isomer space of [CnCmim]+ yields close to 386 000 cation structures. Calculating frontier orbital energies for each would be computationally very expensive and time-consuming using DFT. In this article, we develop a machine learning model based on the extreme gradient boosting method using a small subset of the isomer space and predict the HOMO and LUMO energies. Using the model, the HOMO energies are predicted with a mean absolute error (MAE) of 0.4eV and the LUMO energies are predicted with a MAE of 0.2eV. Inferences are also drawn on the type of the descriptors deemed important for the HOMO and LUMO energy estimates. Application of the machine learning model results in a drastic reduction in computational time required for such calculations.

Temperature-dependent interphase formation and Li+ transport in lithium metal batteries

High-performance Li-ion/metal batteries working at a low temperature (i.e., <−20 °C) are desired but hindered by the sluggish kinetics associated with Li+ transport and charge transfer. Herein, the temperature-dependent Li+ behavior during Li plating is profiled by various characterization techniques, suggesting that Li+ diffusion through the solid electrolyte interface (SEI) layer is the key rate-determining step. Lowering the temperature not only slows down Li+ transport, but also alters the thermodynamic reaction of electrolyte decomposition, resulting in different reaction pathways and forming an SEI layer consisting of intermediate products rich in organic species. Such an SEI layer is metastable and unsuitable for efficient Li+ transport. By tuning the solvation structure of the electrolyte with a lower lowest unoccupied molecular orbital (LUMO) energy level and polar groups, such as fluorinated electrolytes like 1 mol L−1 lithium bis(fluorosulfonyl)imide (LiFSI) in methyl trifluoroacetate (MTFA): fluoroethylene carbonate (FEC) (8:2, weight ratio), an inorganic-rich SEI layer more readily forms, which exhibits enhanced tolerance to a change of working temperature (thermodynamics) and improved Li+ transport (kinetics). Our findings uncover the kinetic bottleneck for Li+ transport at low temperature and provide directions to enhance the reaction kinetics/thermodynamics and low-temperature performance by constructing inorganic-rich interphases.

Zerovalent Iron/Cu Combined Degradation of Halogenated Disinfection Byproducts and Quantitative Structure-Activity Relationship Modeling.

Previous studies have reported that zerovalent iron (ZVI) can reduce several aliphatic groups of disinfection byproducts (DBPs) (e.g., haloacetic acids and haloacetamides) effectively, and the removal efficiency can be significantly improved by metallic copper. Information regarding ZVI/Cu combined degradation of different types of halogenated DBPs can help understand the fate of overall DBPs in drinking water distribution and storage systems consisting of unlined cast iron/copper pipes and related potential control strategies. In this study, we found that, besides aliphatic DBPs, many groups of new emerging aromatic DBPs formed in chlorinated and chloraminated drinking water can be effectively degraded by ZVI/Cu; meanwhile, total organic halogen and total ion intensity were reduced significantly after treatment. Moreover, a robust quantitative structure-activity relationship model was developed and validated based on the ZVI/Cu combined degradation rate constants of 14 typical aromatic DBPs; it can predict the degradation rate constants of other aromatic DBPs for screening and comparative purposes, and the optimized descriptors indicate that DBPs possessing a lower value of the lowest unoccupied molecular orbital energy and a higher value of dipole moment tend to present higher degradation rate constants. In addition, toxicity data of 47 DBPs (belonging to 18 groups) were predicted by two previously established toxicity models, demonstrating that, although most DBPs exhibit higher toxicity than their dehalogenated products, some DBPs show lower toxicity than their lowly halogenated analogs.