Total Interaction Energy Research Articles

Pairwise Additivity and Three-Body Contributions for Density Functional Theory-Based Protein-Ligand Interaction Energies.

The prediction of protein-ligand binding energies is crucial in computer-assisted drug design. This property can be calculated in a straightforward fashion as the difference in the energies between a binding site-ligand complex and the separated binding site and ligand. Often, though, there is value in knowing how different amino acid residues in the protein binding site interact with the ligand. In this case, the interaction energy can be calculated as the sum of pairwise energies between each amino acid residue in the binding site and the ligand, and the sum of these energies is often equated with the total interaction energy. The validity of this pairwise additivity approximation can be assessed by experimental evidence, such as double-mutant cycles. In this work, we test the pairwise additivity approximation on the sulfotransferase-l-DOPA complex for 16 density functional theory (DFT) methods with varying degrees of exact (Hartree-Fock) exchange. Several "families" of functionals are studied, including BLYP, B3LYP, and CAM-B3LYP, as well as M06L, M06, and M062X. We also calculate the three-body contributions to interaction energy for the same DFT methods and assess when they are significant. We find that the amount of exact exchange or other nonlocal contributions has a direct influence on how closely the sum of pairwise energies approximates the total interaction energy. We also find that three-body interactions can be significant and that their significance can be predicted with good accuracy.

The effects of NaCl addition on the particle-bubble interactions of galena in the presence of xanthate

This work investigated the effects of NaCl addition on galena flotation in the presence of xanthate. The micro-flotation experiments were performed using NaCl solutions which also included xanthate, at pH 9 (±0.1). Our results indicated that galena recovery improved for higher NaCl as well as higher xanthate concentrations.A pH-dependent chemisorption model for the galena surface, with the addition of xanthate adsorption was calibrated using measured zeta potential values. We propose that xanthate adsorption on galena can take place via two separate mechanisms. The first mechanism involves direct xanthate chemisorption to specific surface sites. The second mechanism involves lead/xanthate complexes formed in the bulk solution. These lead/xanthate complexes attach on the galena surface as hydrophobic lead xanthate salts.The galena-air bubble interactions are repulsive in 1 mM NaCl, with or without xanthate, consistent with the lower galena recovery measured experimentally. An increase to 100 mM NaCl, irrespective of the xanthate addition, resulted in attractive galena-air bubble total interaction energies. The agreement with the experimental results shows the effectiveness of the charge regulated model for estimating the galena and air bubble behaviours during flotation in NaCl solutions.

A novel macroporous biochar as a biocarrier for DMAC biodegradation: Preparation, performance and mechanism

We produced a new biochar composite from waste bamboo powder and used it as a carrier for N,N-dimethylacetamide (DMAC) biodegradation. Characterization results highlighted the biochar composite's macroporous structure, comprising 72.14% of its total pore volume, facilitating bacterial colonization and growth. In comparison to traditional biocarriers and bamboo charcoal-loaded polyurethane (BC-PU), the biochar composite exhibited faster biofilm formation and achieved stability by the 5th day. Due to the increased biomass on the biochar composite, the DMAC degradation rate reached 80.44%, which was 1.5 times greater than that of BC-PU, indicating its potential for treating DMAC in biofilters. The Fourier transform infrared spectroscopy revealed the presence of abundant oxygen-containing functional groups in the biochar composite, which strongly interacted with bacterial adhesion. Selective passivation of oxygen-containing functional groups extended the biofilm formation time from 5 to 10 days, while the introduction of carboxyl groups expedited it by 1 day. Kinetic studies and the Derjaguin–Landau–Verwey–Overbeek theory demonstrated that the oxygen-containing functional groups reduced the total interaction energy and improved the mass transfer capacity of the biochar surface, thereby promoting biofilm formation. This study introduces a macroporous biochar composite with enhanced biodegradation capabilities, outperforming traditional biocarriers in VOCs degradation in bioreactors. The process provides a new direction for future biocarrier preparation.

Unveiling fructose and glucose binding to human serum albumin: fluorescence measurements and docking, molecular dynamics and quantum biochemistry computations

This research examines the interaction between human serum albumin (HSA) and various sugar forms (β-D-fructofuranose (FRC), α-D-glucopyranose (GLC), Keto-D-fructose (FRO), Aldehydo-D-glucose (GLO), and modified Aldehydo-D-glucose (GLOm)) using fluorescent spectroscopy, molecular docking simulations, molecular dynamics, protein conformational clusters (EnGens), molecular fractionation with conjugate caps (MFCC) and quantum biochemistry analysis. We analyze molecular and quantum aspects, uncovering interaction energies between sugar atoms and amino acids. Total interaction energy considers protein fragmentation, energetic decomposition, and interaction energy from a bottom-up perspective. Molecular dynamics reveal that unmodified Aldehydo-D-glucose (GLO) escapes HSA binding sites, explaining gradual glycation. We pioneer studying HSA’s binding mechanism with glucose and fructose in a 1:1 ratio using long molecular dynamics simulations. Results suggest the transitional GLOm form has a higher Sudlow I site propensity than unmodified glucose, crucial for K195 glycation. FRO and GLOm interaction tendencies move toward a deeper FA7 cavity, near its center. This approach effectively elucidates small molecule binding mechanisms, consistent with previous experimental results. Communicated by Ramaswamy H. Sarma

Investigation of protein-protein interactions and hotspot region on the NSP7-NSP8 binding site in NSP12 of SARS-CoV-2.

Background: The RNA-dependent RNA polymerase (RdRp) complex, essential in viral transcription and replication, is a key target for antiviral therapeutics. The core unit of RdRp comprises the nonstructural protein NSP12, with NSP7 and two copies of NSP8 (NSP81 and NSP82) binding to NSP12 to enhance its affinity for viral RNA and polymerase activity. Notably, the interfaces between these subunits are highly conserved, simplifying the design of molecules that can disrupt their interaction. Methods: We conducted a detailed quantum biochemical analysis to characterize the interactions within the NSP12-NSP7, NSP12-NSP81, and NSP12-NSP82 dimers. Our objective was to ascertain the contribution of individual amino acids to these protein-protein interactions, pinpointing hotspot regions crucial for complex stability. Results: The analysis revealed that the NSP12-NSP81 complex possessed the highest total interaction energy (TIE), with 14 pairs of residues demonstrating significant energetic contributions. In contrast, the NSP12-NSP7 complex exhibited substantial interactions in 8 residue pairs, while the NSP12-NSP82 complex had only one pair showing notable interaction. The study highlighted the importance of hydrogen bonds and π-alkyl interactions in maintaining these complexes. Intriguingly, introducing the RNA sequence with Remdesivir into the complex resulted in negligible alterations in both interaction energy and geometric configuration. Conclusion: Our comprehensive analysis of the RdRp complex at the protein-protein interface provides invaluable insights into interaction dynamics and energetics. These findings can guide the design of small molecules or peptide/peptidomimetic ligands to disrupt these critical interactions, offering a strategic pathway for developing effective antiviral drugs.

A novel pyrazole derivative as COVID-19 main protease inhibitor: Synthesis, quantum computational studies, pharmacokinetic properties, drug likeness, molecular docking and dynamics simulation; a CADD approach

2-(3‑bromo-1-(3-chloropyridin-2-yl)-1H-pyrazol-5-yl)-8-methyl-4H benzo[d][1,3]oxazin-4-one (2-BCBO) compound, was synthesized by the reaction of 3‑bromo-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxylic acid in acetonitrile and methane sulfonyl chloride. The monoclinic crystal structure in C2/c space group of the compound was unveiled through single-crystal X-ray diffraction studies. A prediction model was employed to investigate the influence of intermolecular contacts on molecular packing in the crystalline phase. The model incorporated both Hirshfeld surface and 2D fingerprint models to gain a comprehensive understanding of the strength of these contacts. The calculation of the total interaction energy was conducted by utilizing the three-dimensional molecular energy frameworks and further, employed density functional theory to examine molecular orbital characteristics and key factors associated with chemical reactivity. The application of topological analysis techniques, such as QTAIM and NCI, provided further insight regarding the attraction and repulsive interactions shown by the molecule. The pharmacokinetic properties of the 2-BCBO molecule have also been examined using ADMET analysis, which is important in drug discovery and development. In addition, the molecular docking study to determine the inhibitory effect of the investigated ligand on the main protease of new coronavirus (COVID-19), followed by molecular dynamics simulations, and it is found that both the results are in good agreement. The 2-BCBO could be accepted as a lead molecule to treat the coronavirus.

Comparative Analysis of Nickel-Phosphine Complexes with Cumulated Double Bond Ligands: Structural Insights and Electronic Interactions via ETS-NOCV and QTAIM Approaches.

This study presents a comprehensive analysis of nickel-phosphine complexes, specifically Ni(PH3)2(OCCH2), Ni(PH3)2(H2CCO), Ni(PH3)2(H2CCCH2), Ni(PH3)2(NNCH2), and Ni(PH3)2(η1-H2CNN). Utilizing ETS-NOCV analysis, we explored orbital energy decomposition and the Hirshfeld charges of the ligands, providing insights into the electronic structures and donor-acceptor interactions within these complexes. The interactions in the ketene and allene complexes exhibit similar deformation densities and NOCV orbital shapes to those calculated for Ni(PH3)2(NNCH2), indicating consistent interaction characteristics across these complexes. The total interaction energy for all η2 complexes is observed to be over 60 kcal/mol, slightly exceeding that of the analogous carbon dioxide complex reported earlier. Furthermore, the study highlights the stronger back-donation as compared to donor interactions across all η2 complexes. This is further corroborated by Hirshfeld analysis, revealing the charge distribution dynamics within the ligand fragments. The research offers new perspectives on the electron distribution and interaction energies in nickel-phosphine complexes, contributing to a deeper understanding of their catalytic and reactive behaviors.

Exploring the effect of substituents on the supramolecular assemblies built by non-covalent interactions in three closely related 1,3,4-oxadiazole-2(3H)-thione derivatives: An evaluation of antimicrobial and anti-proliferative activities

Three closely related 1,3,4-oxadiazole-2(3H)-thione N-Mannich bases were synthesized and characterized by spectroscopic and single crystal X-ray diffraction methods. X-ray analysis reveals that the title molecules adopt l-shaped conformation, and a slight structural deviation around substituent groups is noted. The Hirshfeld surface and 2D fingerprint plots demonstrate the effect of substituents (piperidine, morpholine, and thiomorpholine) on the intermolecular interactions. The CLP-PIXEL energy analysis identified the most significant interactions in the molecular dimers (that characterize the crystal packing) with respect to the total intermolecular interaction energies. These dimers are held together by various non-covalent interactions including C–H⋅⋅⋅S/N/O/Cl/π interactions in addition to unconventional lone pair⋅⋅⋅π interactions. A molecule with thiomorpholine substituent is favoured by two σ-hole interactions (Cl⋅⋅⋅Cl halogen bond and S⋅⋅⋅N chalcogen bond) in the solid state. Furthermore, the molecular electrostatic potential (MEP) surfaces and deformation electron density help to describe the existence of σ-hole on the Cl and thione S atoms. Noncovalent interaction index (NCI) and quantum theory of atoms in molecules (QTAIM) methods are used to delineate the nature of observed noncovalent interactions in the molecular dimers. In vitro data of antibacterial and anti-proliferative activities indicate that compound with morpholine substituent showed a moderate antibacterial activity against all tested Gram-positive bacterial strains. However, molecules with piperidine and thiomorpholine showed notable effectiveness against the HepG-2 cell line. Molecular docking analysis was performed with two liver cancer targets, VEGFR2 and RET, in order to understand the interactions between the ligand and the active site residues of these targets.

The bonding situations in ruthenium chalcogenonitrosyl compounds: a physical reasoning.

This research presents, for the first time, a comprehensive and rigorous investigation of ruthenium(II) chalcogenonitrosyl bonding situations in two sets of coordination compounds: [Ru(NE)Cl2(LOEt)] (1a-4a) and [Ru(NE)Cl2(LOEt)]- (1b-4b), where E = O, S, Se, Te. Prior to and following the one-electron reduction, the Ru-NE bonding situations were subjected to analysis. The calculated geometric parameters indicate that both the Ru-NE and N-E bond lengths are susceptible to variation depending on the nature of the chalcogen employed. Furthermore, the results demonstrate that the one-electron reduction process serves to diminish the NE double bond character. The generalized Kohn-Sham energy decomposition analysis (GKS-EDA) was conducted to illustrate the Ru-NE bonding scenarios prior to and following the one-electron reduction. The results provide valuable insights into the nature of Ru(II)-NE (E = O, S, Se, Te) bonds, the influence of chalcogens on ruthenium compounds, as well as how the one-electron reduction affects the release of NE groups. The main findings indicate that the total interaction energy, prior to the one-electron reduction, is three to four times more stabilizing than in the reduced analogs, confirming that the reduction unequivocally enhances the lability of the Ru-NE bond even when heavier chalcogen analogues are employed.

Theory and simulations of light-induced self-assembly in colloids with quantum chemistry derived empirical potentials.

Light-induced self-assembly (LISA) is a non-invasive method for tuning material properties. Photoresponsive ligands coated on the surfaces of nanoparticles are often used to achieve LISA. We report simulation studies for a photoresponsive ligand, azobenzene dithiol (ADT), which switches from a trans-to-cis configuration on exposure to ultraviolet light, allowing self-assembly in ADT-coated gold nanoparticles (NPs). This is attributed to a higher dipole moment of cis-ADT over trans-ADT which leads to a dipole-dipole attraction facilitating self-assembly. Singh and Jha [Comput. Theor. Chem., 2021, 1206, 113492] used quantum-chemistry calculations to quantify the interaction energy of a pair of ADT ligands in their cis and trans conformations. The interaction energy between ligands was fit to a potential energy function of the Lennard-Jones (LJ) form having distinct exponents for attractive and repulsive contributions. Using this generalized equation for the ligand-ligand interaction energy, we calculated the total effective interaction energy between a pair of cis as well as trans ADT-coated NPs. Specifically, we calculated the effective interaction energies between cis/trans-NPs using discrete as well as continuous approaches. Given the limitations of experiments in probing individual ligand conformations, we also studied the effect of varying the functional ligand length on the interaction energy between NPs and identified the optimal functional ligand length to capture the steric and conformational effects. Finally, using the effective interaction energy, we obtained a generalized potential energy function, which was applied in Langevin dynamics simulations to capture self-assembly in NPs.

Superhalogens inside fullerenes X@C2n (X = BO2, BeF3; 2n = 60, 70).

The exploration of endohedral fullerenes has garnered significant attention recently due to their distinctive chemical, electrochemical, and optoelectronic properties. Charge transfer, which usually occurs from encapsulated species to fullerenes, importantly affects the structures and properties of endohedral fullerenes. In this study, we theoretically investigated endohedral superhalogen fullerenes X@C2n (X = BO2, BeF3; 2n = 60, 70), in which the charge is reversely transferred from the fullerene to the superhalogen, by using density functional theory calculations and ab initio molecular dynamics simulations. Both natural population analysis and the quantum theory of atoms in molecules confirm about one electron transfer from the fullerene to the superhalogen, resulting in the formal valence state of X-@C2n+. Energy decomposition analysis on the interaction between the superhalogen and fullerene revealed that electrostatic energy contributes predominantly to the total interaction energy. These endohedral superhalogen fullerenes with cationic fullerenes were predicted to be able to serve as building blocks for one dimensional fullerene-based nanowires when combined with endohedral alkali-metallofullerenes with anionic fullerenes.

Unraveling the orientation of an enzyme adsorbed onto a metal-organic framework.

Bio-conversion of lignocellulosic biomass to bioethanol fuel is a highly desirable yet challenging objective because of the low catalytic activity and high cost of β-glucosidase (BGL). Recently, ZIF-8, an emerging organic porous material, has been proposed as a promising candidate for enzyme immobilization to improve associated activity and stability. However, the underlying interaction mechanism of binding BGL on the ZIF-8 surface is yet to be clarified. Here, the adsorption of BGL onto ZIF-8 is explored for the first time by molecular dynamics simulations. The results show that BGL adsorbs on the ZIF-8 surface with a "back-on" orientation. The adsorption free energy analysis shows that the adsorption process is enthalpy driven. In addition, the electrostatic interaction between negatively charged residues and Zn2+ on the surface of ZIF-8 is found to play a decisive role in surface binding, which accounts for 98% of the total interaction energy. The secondary structure of BGL is not affected despite the strong adsorption, suggesting the good biocompatibility of ZIF-8. This study not only provides a reliable theoretical insight into understanding the interaction mechanism between BGL and ZIF-8, but also helps the rational design of ZIF-8-based materials for bio-related applications.

Benchmarking Swaths of Intermolecular Interaction Components with Symmetry-Adapted Perturbation Theory.

A benchmark database for interaction energy components of various noncovalent interactions (NCIs) along their dissociation curve is one of the essential needs in theoretical chemistry, especially for the development of force fields and machine-learning methods. We utilize DFT-SAPT or SAPT(DFT) as one of the most accurate methods to generate an extensive stock of the energy components, including dispersion energies extrapolated to the complete basis set limit (CBS). Precise analyses of the created data, and benchmarking the total interaction energies against the best available CCSD(T)/CBS values, reveal different aspects of the methodology and the nature of NCIs. For example, error cancellation effects between the S2 approximation and nonexact xc-potentials occur, and large charge transfer energies in some systems, including heavy atoms, can explain the lower accuracy of DFT-SAPT. This method is perfect for neutral complexes containing light nonmetals, while other systems with heavier atoms should be treated carefully. In the last part, a representative data set for all NCIs is extracted from the original data.

Enriched functional exoproteins and increased exopolysaccharides with altered molecular conformation mutually promoted indigenous microalgal-bacterial consortium biofilm growth under high light intensity

Indigenous microalgal-bacterial consortium (IMBC) biofilm technology holds great promise for wastewater treatment. However, the efficient start-up of IMBC biofilm system remains a technical challenge, partially impeding its large-scale application due to the unclear biofilm formation mechanism. In this study, high light intensity (HL) irradiation was firstly demonstrated as an effective strategy to promote IMBC biofilm development, as evidenced by the 498.3% higher biofilm formation ratio on average. Interaction energy between IMBC and carrier, exoproteins (PN) annotation and exopolysaccharides (PS) chain characteristics were investigated to reveal the potential mechanism. The decreased interfacial free energy (by 33.8%) and negative total interaction energies between IMBC and carriers in the HL group indicated enhanced microbial initial adhesion onto carriers. PN and PS were believed to mutually promote biofilm proliferation. Specifically, enriched PN with signal transduction potential and transmembrane transporter activity ensured efficient production of extracellular polymeric substances (EPS) for biofilm development. On one hand, PN annotated with binding capacities contributed to a tightly-interconnected EPS matrix. On the other hand, the increased PS with higher branding degree, height, and width (by 473%, 63.4%, and 28.9%, respectively) significantly enhanced the structural stability of biofilm landscape. These findings enrich our knowledge of the roles of EPS in IMBC biofilm growth, and are expected to promote the development of IMBC wastewater bioremediation technology.

Insights into the effect of ethyl xanthate on the adhesion and biofilm formation by Acidianus manzaensis on chalcopyrite

Adhesion and biofilm formation play important roles in the bio-dissolution of metal sulfides, which can initiate dissolution and enhance bioleaching. Ethyl xanthate, a commonly used flotation reagent, remained in flotation concentrates of metal sulfides and may have an impact on the bioleaching of metal sulfides. Therefore, it is important to analyze the effect of ethyl xanthate on microbial initial adhesion and biofilm formation. The results showed that the adhesion percentage of Acidianus manzaensis on chalcopyrite decreased with increasing ethyl xanthate concentration after adsorption equilibrium, due to the toxicity of ethyl xanthate to A. manzaensis. However, a low concentration (0.01 mg/L) of ethyl xanthate had little effect on the growth of A. manzaensis. The hydrophobicity of chalcopyrite increased after the addition of ethyl xanthate, leading to an increase in total interaction energy and adhesion force. The presence of ethyl xanthate inhibited the early growth of biofilm and delayed the formation of microcolonies on chalcopyrite. While biofilm coverage was larger with the addition of ethyl xanthate than that of the control when biofilm was mature. Furthermore, in the presence of ethyl xanthate, more and larger microcolonies were observed on the chalcopyrite surface when biofilm was matured, resulting in an increased corrosion degree and more jarosite produced on the chalcopyrite surface. This study suggested that a low concentration (0.01 mg/L) of ethyl xanthate could promote the dissolution of chalcopyrite, which could be significant for bioleaching of flotation reagent-bearing flotation concentrates.

Exploring the potential of deep eutectic solvents for extracting bioactive compounds from tea: Insights from molecular dynamics simulations

Deep eutectic solvents (DESs) are sustainable alternatives to traditional solvents used for natural compound extraction. In this study, the possibility of extracting alkaloids, flavonoids, and catechin compounds from tea plants is investigated using four different binary eutectic solvents through molecular dynamics (MD) simulations and Density functional theory (DFT) calculations. The structural and thermodynamic characteristics of the solvents, as well as their interactions with the tea's bioactive components, are explored. In this study, choline chloride (CHO) is combined with 1,2-butanediol (1,2BUT), 1,3-butanediol (1,3BUT), 1,4-butanediol (1,4BUT), and 2,3-butanediol (2,3BUT) to produce four different types of solvents. According to the obtained results from the MD simulation, the interaction of the target compounds with the different DESs varied significantly, some of the solvents are more soluble and show a good selectivity for certain compounds. The average total interaction energy of target molecules with the solvents follows the order Epigallocatechin (EGC) > Epicatechin gallate (ECG) > Epigallocatechin gallate (EGCg) > Kaempferol (KAM) > Theobromine (TBM) > Caffeine (CAF) > Catchin (CAT). Therefore, among the target molecules, EGC interacts more effectively with solvents. The interaction energy of this molecule with the solvent is changed from −24 kJ/mol to −95 kJ/mol. Overall; this study highlights the importance of considering the specific target compounds when selecting a binary eutectic solvent for extraction and provides a theoretical basis for further experimental investigations.

Synthesis, crystal structure, Hirshfeld surface, QTAIM, NCI-RDG, DFT and molecular docking studies of 4-(aryl)-1,4-dihydro-N,1-dimethyl-6-(methylthio)-3,5-dinitropyridin-2-amines

Two single crystals, 4-(2-ethoxyphenyl)-1,4-dihydro-N,1-dimethyl-6-(methylthio)-3,5-dinitropyridin-2-amine (EDMDA) and 4-(4-fluorophenyl)-1,4-dihydro-N,1-dimethyl-6-(methylthio)-3,5-dinitropyridin-2-amine (FDMDA) compounds have been synthesized by one pot multicomponent reaction. Single crystal X-ray diffraction (SC-XRD) technique has been utilized to determine the molecular structure of EDMDA and FDMDA compounds, which are crystalized into triclinic with P-1 and monoclinic with P1 21 C1 space group respectively. Both EDMDA and FDMDA crystal structures are stabilized by intramolecular and intermolecular N-H···O hydrogen bonding. Further, the intramolecular interactions are studied by QTAIM and NCI-RDG analysis, whereas the intermolecular interactions have been quantified by 3D Hirshfeld surface and 2D fingerprint analysis. Additionally, energy framework analysis has been determined for the title compounds and utilized to explore the individual and total interaction energy between the each molecule. Frontier molecular orbital (HOMO-LUMO) plots and molecular electrostatic potential (MEP) surface are obtained to gain more insight into the electronic properties and reactive sites of chemical species. Finally, the molecular docking studies have carried out for the title compounds with EGFR and VEGFR tyrosine kinase (PDB IDs: 4WKQ, 6JOL, 4AGC and 4AGD) receptors. The studies revealed that the ligands have a greater binding affinity with the chosen EGFR and VEGFR receptors.

Designing a multifunctional TFC membrane with improved permeability and anti-biofouling performance using zwitterionic, quaternary ammonium, and fluorinated materials

A novel copolymer architecture integrating anti-fouling, bactericidal, and fouling-release functions has been developed for thin-film composite (TFC) membranes to effectively address biofouling concerns. The approach involves growing three functional polymers from membrane surface in sequence. The first polymer has low surface energy, the second has bactericidal properties, and the third has a strong hydration capacity. The presence of the multifunctional layer significantly increased water permeability, which is due to the swelling property of the functional polymer. The extended Derjauguin-Landau-Verway-Overbeek (XDLVO) theory analysis shows that the introduction of the multifunctional copolymer architecture increased membrane-foulant total interaction energy (ΔGTOT) from 22.6 to 35.6 mJ/m2, indicating promising anti-adhesive properties. These properties have been confirmed by an 86 % decrease in E. coli adsorption during static bacteria assay. In addition, the fluoropolymer in modified membrane enhances its self-cleaning ability, which has been verified in static fouling-release assays where the TFC membrane can release attached cells under gentle agitation. Our long-term biofouling experiments further confirmed the superior multi-defense properties of the modified TFC membrane. Comparatively, the multifunctional membrane significantly reduced flux decline by 58 % and TOC biomass by 69 % during the dynamic biofouling process, and notably enhanced flux recovery of ∼97 % after cleaning. Our new copolymer architecture highlights the potential to enhance the efficiency and longevity of TFC membranes in a variety of applications.

Removal of methylene blue by acrylic polymer adsorbents loaded with magnetic iron manganese oxides: Synthesis, characterization, and adsorption mechanisms

Dyes pose significant risks for aquatic environments and biological health in general owing to their non-biodegradable nature, carcinogenicity, and toxicity. The effective treatment of dye wastewater has become an important research topic. In this study, acrylic polymers (AP) loaded with magnetic iron manganese oxides (MIMO) (AP/MIMO) were prepared and used for the first time for the adsorption of methylene blue (MB). Carbon in AP/MIMO exists predominantly in the C–H and C–C forms, with its content reaching 50.7%. Oxygen and nitrogen in AP/MIMO exist mainly in the –CO- and -N-C forms, with contents of up to 41.5% and 73.3%, respectively. MB removal by AP/MIMO was consistent with the pseudo-second-order kinetic model (R2 = 0.99), equilibrium was achieved within 20 min, and the highest MB capacity of 2611.23 mg g−1 was predicted by the Langmuir isotherm model (R2 = 0.91–0.94). AP/MIMO exhibited excellent MB adsorption performance in the pH range of 4–10, with a removal efficiency higher than 99.0% (MB = 100 mL 1000 mg L−1; AP/MIMO = 50 mg). Thermodynamic indicators, such as positive entropy (ΔS0; 98.30 J⋅mol−1⋅K−1), negative Gibbs free energy (ΔG0; −29.40, −28.50, and −27.50 KJ⋅mol−1), and positive enthalpy (ΔH0; 2.30 KJ⋅mol−1), demonstrated that MB removal by AP/MIMO was autonomous, favorable, and endothermic. In addition, the integration of experimental results and theoretical calculations verified that electrostatic interactions were the primary mechanism for MB adsorption at carboxyl sites on AP/MIMO. The total interaction energy between AP and MB was −310.43 kJ⋅mol−1, and the electrostatic effect had a decisive contribution to the MB adsorption, with a value of up to −341.06 kJ⋅mol−1. AP and MB were most likely bound by –COO and S atoms. Overall, AP/MIMO exhibits high adsorption capacity and shows potential as a high-performance magnetic polymer for MB removal.

Combining Force Fields and Neural Networks for an Accurate Representation of Chemically Diverse Molecular Interactions.

A key goal of molecular modeling is the accurate reproduction of the true quantum mechanical potential energy of arbitrary molecular ensembles with a tractable classical approximation. The challenges are that analytical expressions found in general purpose force fields struggle to faithfully represent the intermolecular quantum potential energy surface at close distances and in strong interaction regimes; that the more accurate neural network approximations do not capture crucial physics concepts, e.g., nonadditive inductive contributions and application of electric fields; and that the ultra-accurate narrowly targeted models have difficulty generalizing to the entire chemical space. We therefore designed a hybrid wide-coverage intermolecular interaction model consisting of an analytically polarizable force field combined with a short-range neural network correction for the total intermolecular interaction energy. Here, we describe the methodology and apply the model to accurately determine the properties of water, the free energy of solvation of neutral and charged molecules, and the binding free energy of ligands to proteins. The correction is subtyped for distinct chemical species to match the underlying force field, to segment and reduce the amount of quantum training data, and to increase accuracy and computational speed. For the systems considered, the hybrid ab initio parametrized Hamiltonian reproduces the two-body dimer quantum mechanics (QM) energies to within 0.03 kcal/mol and the nonadditive many-molecule contributions to within 2%. Simulations of molecular systems using this interaction model run at speeds of several nanoseconds per day.