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Four acridinium/acridine derivatives have been prepared by mechanochemical synthesis and their crystal structure, supramolecular framework, interaction energy calculation, thermal analysis, and photophysical properties are studied and presented in this manuscript. In the crystal structure, the one- and two-dimensional supramolecular framework is constructed via various strong and weak intermolecular interactions such as N‒H...Cl, O‒H...N, O‒H...Cl, C‒H...Cl, C‒H...O, C‒H...π, and π...π, respectively. The contribution of intermolecular interaction in the three-dimensional molecular packing is studied by the Hirshfeld surface analysis. The calculated total energy value of intermolecular interaction/contacts observed between the molecular pairs in the acridine compound is stronger than the energy value of intermolecular interaction/contacts of acridinium derivatives. The energy value of π...π contacts exhibited between the molecular pairs is significantly stronger than other weak interactions. The thermogravimetric analysis reveals that the acridinium derivatives degrade in three steps whereas the acridine compound undergoes a single-step degradation. Studies show that the acridinium derivatives exhibit a better photoluminescence quantum yield when compared to the acridine compound, and the acridine compound experiences a photoluminescence quenching due to charge transfer interactions. [ABSTRACT FROM AUTHOR]

To investigate the mechanism underlying the effect of mixed collector (MC) composed of diesel and span-80 on LRC flotation, a combination of experimental and molecular simulation approaches was employed. The flotation results demonstrated that the use of MC yielded superior flotation performance compared to diesel alone. The ratio of diesel to span-80 emerged as a key factor influencing the performance of MC collection. Furthermore, molecular dynamics (MD) simulations were employed to investigate the adsorption processes of dodecane and MC molecules on the LRC surface in the LRC/dodecane/water and LRC/MC/water systems, respectively. The analysis encompassed microstructure, dynamic properties, interaction energy, and hydrogen bonding. The findings indicated that the presence of span-80 molecules facilitated the direct entry of dodecane molecules in MC into "microscopic cavities," thereby enhancing the adsorption of MC on the LRC surface. The analysis of interaction energy revealed a stronger interaction between MC molecules and the coal surface, with van der Waals energy playing a major role in the adsorption process. Additionally, span-80 molecules induced hydrogen bonding adsorption on the LRC surface. [ABSTRACT FROM AUTHOR]

We introduce the fragment‐pairwise Local Energy Decomposition (fp‐LED) scheme for precise quantification of individual interactions contributing to the binding energy of arbitrary chemical entities, such as protein‐ligand binding energies, lattice energies of molecular crystals, or association energies of large biomolecular assemblies. Using fp‐LED, we can assess whether the contribution to the binding energy arising from noncovalent interactions between pairs of molecular fragments in any chemical system is attractive or repulsive, and accurately quantify its magnitude at the coupled cluster level ‐ commonly considered as the “gold standard” of computational chemistry. Such insights are crucial for advancing molecular and material design strategies in fields like catalysis and therapeutic development. Illustrative applications across diverse fields demonstrate the versatility and accuracy of this theoretical framework, promising profound implications for fundamental understanding and practical applications. [ABSTRACT FROM AUTHOR]

We have investigated the basic mechanism of carbon nanotube (CNT) interactions with various room-temperature ionic liquids (RTILs) using molecular dynamics (MD) simulations. To understand the effects of the cation molecular geometry on the properties of the interface structure in the RTIL systems, we have studied a set of three RTILs with the same [BF4]- (tetrafluoroborate) anion but with different cations, namely, [EMIM]+ (1-ethyl-3-methylimidazolium), [BMIM]+ (1-butyl-3-methylimidazolium), [HMIM]+ (1-hexyl-3-methylimidazolium), and [OMIM]+ (1-octyl-3-methylimidazolium) ions. The simulation results showed that the imidazolium cations exhibit two distinct orientations (perpendicular and parallel to the CNTs surface) at the interface irrespective of the alkyl chain length of the cations. The average number of hydrogen bonds per cations inside the CNT was found to be higher for [OMIM][BF4] (1.01), which suggests that [OMIM]+ imidazolium rings to be concentrated at the center of the CNT, which favors hydrogen bond. The reported results show the diffusion coefficients of ions in confinement are much lower in comparison to the bulk region. The interaction energy between [OMIM][BF4] (-8.75 kcal.mol−1.ion−1) and CNT was found to be higher as compared to other ILs. The cations paralleling the CNT surface are thermodynamically significantly more stable because of the substantial interfacial π-π stacking interactions, as shown by a comparison with the calculated interaction energies between cations and the CNTs. Our simulation results provide a molecular-level understanding of the stabilization and dispersion of CNT bundles in ILs. [ABSTRACT FROM AUTHOR]

This study aims to cast light on the nature of hydrogen bonds and their cooperativity that exists in alcohol-water ( $ \textrm{ROH}{({{\textrm{H}_2}\textrm{O}})_\textrm{n}} $ ROH ( H 2 O ) n ) ( $ \textrm{R} = - \textrm{C}{\textrm{H}_3}\textrm{ }({ - \textrm{Me}}),\textrm{ } - \textrm{C}{\textrm{H}_2}\textrm{C}{\textrm{H}_3}\textrm{ }({ - \textrm{Et}}) $ R = − C H 3 (− Me) , − C H 2 C H 3 (− Et)) (n = 1–10) clusters using atoms in molecules (AIM) theory and symmetry-adapted perturbation theory (SAPT). The investigation of optimum structures suggests that alcohol ( $ \textrm{ROH} $ ROH ) forms two hydrogen bonds, one primary hydrogen bond $ ({\textrm{O} - \textrm{H} \cdot \cdot \cdot \textrm{O}}) $ (O − H ⋅ ⋅ ⋅ O) , and one secondary hydrogen bond $ ({\textrm{C} - \textrm{H} \cdot \cdot \cdot \textrm{O}}) $ (C − H ⋅ ⋅ ⋅ O) Two types of hydrogen bonds are addressed in these studies, where alcohol works as the hydrogen bond donor $ ({\textrm{ROH} \cdot \cdot \cdot \textrm{O}{\textrm{H}_2}}) $ (ROH ⋅ ⋅ ⋅ O H 2 ) and hydrogen bond acceptor $ ({\textrm{RHO} \cdot \cdot \cdot \textrm{HOH}}) $ (RHO ⋅ ⋅ ⋅ HOH). The AIM results reveal that $ \textrm{RHO} \cdot \cdot \cdot \textrm{HOH} $ RHO ⋅ ⋅ ⋅ HOH and $ \textrm{ROH} \cdot \cdot \cdot \textrm{O}{\textrm{H}_2} $ ROH ⋅ ⋅ ⋅ O H 2 hydrogen bonds are partially covalent. The SAPT study demonstrates that in all the clusters studied herein, the electrostatic interaction between alcohol and water is the main attractive force, and its contribution may be two times larger than the separate corresponding contributions from the dispersion and the induction terms. The electron density (ρ) at the bond critical point (BCP) is a suitable parameter to assess the strength of the interaction. The current study shows the strength and nature of $ \textrm{ROH} \cdot \cdot \cdot \textrm{O}{\textrm{H}_2} $ ROH ⋅ ⋅ ⋅ O H 2 and $ \textrm{RHO} \cdot \cdot \cdot \textrm{HOH} $ RHO ⋅ ⋅ ⋅ HOH hydrogen bond, and cooperative effect in ( $ \textrm{ROH}{({{\textrm{H}_2}\textrm{O}})_\textrm{n}} $ ROH ( H 2 O ) n ) ( $ \textrm{R} = - \textrm{C}{\textrm{H}_3}\textrm{ }({ - \textrm{Me}}),\textrm{ } - \textrm{C}{\textrm{H}_2}\textrm{C}{\textrm{H}_3}\textrm{ }({ - \textrm{Et}}) $ R = − C H 3 (− Me) , − C H 2 C H 3 (− Et).) (n = 1–10). [ABSTRACT FROM AUTHOR]

Starting from (p‐tolylsulfinyl)ferrocene (1), a mixture of the complete series [CpFe{C5H5–n(SOTol‐p)n}] (n = 2–4) (2–4) in all regioisomers was obtained. After chromatographic separation, crystals of 1,2‐bis[(4‐methylbenzene)sulfinyl]ferrocene, 2a, and 1,3‐bis[(4‐methylbenzene)sulfinyl]ferrocene, 2b, both [Fe(C5H5)(C19H17O2S2)], as well as of 1,2,3‐tris[(4‐methylbenzene)sulfinyl]ferrocene, [Fe(C5H5)(C26H23O3S3)], 3a, and 1,2,3,4‐tetrakis[(4‐methylbenzene)sulfinyl]ferrocene ethyl acetate 0.75‐solvate, [Fe(C5H5)(C33H29O4S4)]·0.75C4H8O2, 4, could be isolated. Their molecular and crystal structures are compared with each other and also with the so far unreported structures of related 1,2‐bis(phenylsulfanyl)ferrocene, [Fe(C5H5)(C17H13S2)], 5, and 1,2,3,4‐tetrakis(phenylsulfanyl)ferrocene, [Fe(C5H5)(C29H21S4)], 6. In all the sulfinyl structures, the O atoms of the S=O groups are in equatorial positions, except for that in tetrasubstituted 4. All the arene rings of these compounds (except for one ring in 4) are in axial positions directed away from the Fe atom, mostly in a near perpendicular orientation with respect to the plane of the cyclopentadienyl ring. The main intermolecular interactions in the crystals are C—H...H—C, C—H...π and C—H...O, while C—H...S interactions are much less important, except for tetrasulfanyl compound 6. π–π interactions (intramolecular) are only important in compound 3a. Hirshfeld analysis shows that dispersion terms are dominant for the interaction energies of all six compounds. In general, the calculated total interaction energies increase with increasing number of substituents and are higher for the sulfinyl than for the sulfanyl groups. [ABSTRACT FROM AUTHOR]

This work conducts a comprehensive theoretical study on the non‐covalent complexation between cyclocarbons and C60 fullerene for the first time. The binding energy between cyclocarbons and C60 fullerene is significantly stronger than that between two C18 or two C60 fullerenes, indicating a particularly strong affinity. The cyclocarbons and C60 fullerene can spontaneously assemble into complexes in the gas phase at room temperature, and the hydrophobic effect caused by the solvent environment can promote this binding. The binding strength with C60 fullerene increases almost linearly with the increase of cyclocarbon size, and the C34@C60 dimer exhibits a perfect nano‐Saturn structure. As the ring size increases, the angle between the two cyclocarbons of the 2 : 1 trimers formed by cyclocarbons and C60 fullerene gradually decreases. In C60@2 C34 trimer, the fullerene is symmetrically surrounded by two cyclocarbons. The results on the trimers formed by cyclocarbon and C60 fullerenes in a 1 : 2 ratio showed when the cyclocarbon sandwiched between two fullerenes is not quite large, the trimers exhibit an ideal dumbbell‐like structure, and the presence of the first fullerene has a significant synergistic effect on the binding of the second one. The cyclocarbon greatly promotes the dimerization of fullerenes, which acted as a "molecular glue". [ABSTRACT FROM AUTHOR]

Solid-state drug delivery systems for the drug substances transport are of great importance nowadays. In the present work, the non-covalent interactions between taxifolin (Tax) and graphene as well as nitrogenated (N-doped) graphenes were systematically studied by using a wide set of theoretical techniques. Symmetry-adapted perturbation theory (SAPT0) calculations confirmed more favorable adsorption of Tax on N-doped graphenes compared to pristine graphene. It was established that dispersion interactions play the main role in the attractive interactions (>60%), whereas electrostatic and induction forces contribute only moderately to the attraction (~25% and 7–8%, respectively). Independent gradient model (IGM) analysis visually demonstrated the existence of dispersion interactions and hydrogen bonding in the studied Tax complexes. Ab initio molecular dynamics calculations indicated stability of these complexes at different temperatures. Our results show that N-doped graphenes with the enhanced interaction energy (Eint) toward Tax are promising candidates for the technical realization of the targeted drug delivery systems. [ABSTRACT FROM AUTHOR]

Asphaltene deposition poses a significant threat to the safe production of crude oil as it tends to occur in forming porous media, wellbores, pipelines, and refining equipment. It is also responsible for the high viscosity of crude oil, making it challenging to recover heavy crude oil. This study investigates the impact of aliphatic chain length on asphaltene aggregation and the molecular properties of organic solvents and dispersants interacting with asphaltenes. To achieve this, two model asphaltenes, M1 and C5Pe, were used in molecular dynamics simulations using radial distribution function, root means square displacement, diffusion coefficient, solubility parameter, cohesion energy density, and interaction energy as characterization parameters. The simulations revealed that the aggregation onset of C5Pe and M1 occurs at 2–5 Å at room temperature and pressure, and π–π stacking is the primary mode of aggregation, with the presence of heteroatomic groups providing additional forces for stable aggregation. Additionally, it was found that the π–π interactions weakened with the increase of the side chain length. The study also investigated the molecular behavior of asphaltenes in six organic solvents and found that M1 was more soluble in aromatic solvents than C5Pe, and undesirable solvents could induce asphaltene aggregation. Furthermore, the effect of five dispersants on asphaltene aggregation was explored, with PIBSI, BEHP, B-DBSA, CTAB, and benzoic acid showing decreasing dispersing ability in that order at lower concentrations. However, at higher concentrations, the effect of some dispersants diminishes and triggers self-aggregation behavior. [ABSTRACT FROM AUTHOR]

The heat of mixing of some petrological relevant substitutions (i.e., Mg-Al, Si-Al, Mg-Ti, Mg-Ca, and Mg-Fe) was investigated systematically in silicates, titanates, tungstates, carbonates, oxides, hydroxides, and sulphates by density functional theory calculations (e.g., melilite, chlorite, biotite, brucite, cordierite, amphibole, talc, pseudobrookite, pyroxene, olivine, wadsleyite, ilmenite, MgWO4, ringwoodite (spinel), perovskite, pyrope-grossular, magnesite-calcite, MgO-CaO, anhydrous and different hydrated MgSO4). A specific substitution is characterised by different microscopic interaction energies in different minerals, e.g., the octahedral Mg-Al exchange on a single crystallographic site in pyroxene has a microscopic interaction energy that is more than twice compared to that in biotite. A comparative investigation of the heat of mixing using microscopic interaction energies on a single crystallographic site has the advantage that they are not influenced by cation ordering. They could be successfully correlated with the stiffnesses of the minerals, which in turn were scaled to the oxygen packing fraction, a parameter that is easily available for poorly investigated minerals. With this information, the interaction energies of a certain substitution can be transferred from minerals where they are well-known to mineral groups where they are less- or unknown. Using the cross-site terms and the microscopic interaction energies, the macroscopic interaction energies of the coupled substitution, e.g., Mg + Si = Al + Al, of biotite and pyroxene were calculated, which are, however, affected by cation ordering and different degrees of local charge balance, for which appropriate models are necessary. [ABSTRACT FROM AUTHOR]

The benzene dimer (BD) is an archetypal model of π∙∙∙π and C–H∙∙∙π noncovalent interactions as they occur in its cofacial and perpendicular arrangements, respectively. The enthalpic stabilization of the related BD structures has been debated for a long time and is revisited here. The revisit is based on results of computations that apply the coupled-cluster theory with singles, doubles and perturbative triples [CCSD(T)] together with large basis sets and extrapolate results to the complete basis set (CBS) limit in order to accurately characterize the three most important stationary points of the intermolecular interaction energy (ΔE) surface of the BD, which correspond to the tilted T-shaped (TT), fully symmetric T-shaped (FT) and slipped-parallel (SP) structures. In the optimal geometries obtained by searching extensive sets of the CCSD(T)/CBS ΔE data of the TT, FT and SP arrangements, the resulting ΔE values were −11.84, −11.34 and −11.21 kJ/mol, respectively. The intrinsic strength of the intermolecular bonding in these configurations was evaluated by analyzing the distance dependence of the CCSD(T)/CBS ΔE data over wide ranges of intermonomer separations. In this way, regions of the relative distances that favor BD structures with either π∙∙∙π or C–H∙∙∙π interactions were found and discussed in a broader context. [ABSTRACT FROM AUTHOR]

A computational study on the host–guest complexes of neutral bis(4-nitrophenyl)squaramide (SQ) and halide anions is reported. In the gas-phase, the calculated interaction and stabilization energies indicates a diminishing intrinsic affinity of SQ for anions from fluoride to iodide. The nature of interactions is investigated using Natural Bond Orbital (NBO), Quantum Theory of Atoms in Molecules (QTAIM) along with Energy Decomposition Analysis-Natural Orbitals for Chemical Valence (EDA-NOCV). While electrostatic interactions account for roughly 60% of the total, EDA-NOCV analysis demonstrated increasing contributions of orbital interactions from SQ ⋯ I - to SQ ⋯ F - complexes. In solution, thermodynamic cycle analyses and Gibbs free energy calculations reveal a propensity towards the formation of SQ ⋯ F - , taking into account the influence of solvation energies on the overall stability. The consistent trend observed in selectivity both in the gas phase and in solution suggests that changes in solvation energy do not significantly impact the stability of complexes. The findings were additionally supported by a significant correlation observed between the computed and experimental formation constants. [ABSTRACT FROM AUTHOR]

Thermal recovery techniques for producing oil sands have substantial environmental impacts. Surfactants can efficiently improve thermal bitumen recovery and reduce the required amount of steam. Such a technique requires solid knowledge about the interaction mechanism between surfactants, bitumen, water, and rock at the nanoscale level. In particular, oil sands ores have extremely complex mineralogy as they contain many clay minerals (montmorillonite, illite, kaolinite). In this study, molecular dynamics simulation is carried out to elucidate the unclear mechanisms of clay minerals contributing to the bitumen recovery under a steameanionic surfactant co-injection process. We found that the clay content significantly influenced an oil detachment process from hydrophobic quartz surfaces. Results reveal that the presence of montmorillonite, illite, and the siloxane surface of kaolinite in nanopores can enhance the oil detachment process from the hydrophobic surfaces because surfactant molecules have a stronger tendency to interact with bitumen and quartz. Conversely, the gibbsite surfaces of kaolinite curb the oil detachment process. Through interaction energy analysis, the siloxane surfaces of kaolinite result in the most straightforward oil detachment process. In addition, we found that the clay type presented in nanopores affected the wettability of the quartz surfaces. The quartz surfaces associated with the gibbsite surfaces of kaolinite show the strongest hydrophilicity. By comparing previous experimental findings with the results of molecular dynamics (MD) simulations, we observed consistent wetting characteristics. This alignment serves to validate the reliability of the simulation outcomes. The outcome of this paper makes up for the lack of knowledge of a surfactant-assisted bitumen recovery process and provides insights for further in-situ bitumen production engineering designs. [ABSTRACT FROM AUTHOR]

This study shows the exploration of the gas‐sensing capabilities of C6N8 material against toxic gases like phosphine (PH3) and phosphorous trichloride (PCl3). First‐principles study based on M05‐2X/LanL2DZ (d, p) method was performed to investigate the interaction energy (Eint.), frontier molecular orbitals (FMOs), natural bonding orbital (NBO), noncovalent interactions (NCIs), partial density of states (PDOS), molecular electrostatic potential (MEP), and quantum theory of atoms in molecules (QTAIM) analyses. The interaction energy results showed that PCl3@C6N8 (−23.45 kJ/mol) is more stable than PH3@C6N8 (−14.79 kJ/mol). A considerable decrease in the HOMO‐LUMO band gap of C6N8 was observed as a result of its complexation with the analytes. QTAIM and NCI analyses indicated the presence of weak noncovalent interactions between C6N8 and gases (PH3 and PCl3). SAPT0 analysis was performed to quantify the NCIs. MEP maps of complexes revealed the localization of electronic density on C6N8. The little recovery time of complexes (determined at 300 K) showed that C6N8 can serve as a reusable sensing material against PH3 and PCl3. Our results demonstrate that the C6N8 surface is a reliable material for detecting phosphine and phosphorous trichloride gases. [ABSTRACT FROM AUTHOR]

Binary liquid systems serve as valuable prototypes for comprehending biologically and chemically relevant properties of hydrogen bonds, revealing both noteworthy patterns and anomalies in their behaviour. Aniline, acetone and their binary mixtures with other liquids are used in various industrial processes, drug design, and as cleaning agents. This study is a molecular dynamics exploration of aniline and acetone binary mixture, over a concentration range of 9 : 1–1 : 9 for each component. The investigation includes employing techniques such as radial distribution function (RDF), coordination number calculation, hydrogen bond statistics, and graph theoretical analysis (GTA) through the NetworkX module in python, cluster analysis, Voronoi entropy calculation, interaction energy calculation and FTIR spectroscopy for all concentrations studied. The results uncover a compelling trend: a decrease in the number of hydrogen bonds as the concentration of acetone increases. Additionally, increased acetone concentration correlates positively with the breakdown of larger and more complex hydrogen‐bonded structures, indicating the formation of small hydrogen‐bond structures. [ABSTRACT FROM AUTHOR]

Using carbon-supported (M/C, M = Ag, MnO, MnO2, Mn3O4 and Pd) composite electrodes as the oxygen depolarized cathode (ODC) for chlor-alkali electrolysis, the energy consumption can be greatly reduced. However, the electrode stability and mass transfer process caused by the interaction between the ODC and the electrolyte solution are not very ideal, resulting in low efficiency of the electroreduction reaction, and its mechanism is still unclear. In this work, the interaction model of ORR of M/C electrodes in alkaline NaCl solution (ANS) were constructed, and MD simulation of the models were carried out. Based on the calculation and analysis of the interaction energy, diffusion coefficient and radial distribution function, the interaction law between the carbon-supported composite electrode and ANS was found out, and the interaction mechanism was revealed. The results showed that the interaction between O2 in ANS and different M/C electrodes is mutually attractive at 353 K, and the order is Ag/C > Pd/C > MnO/C > MnO2/C >Mn3O4/C. The change law of diffusion coefficients of O2 in different M/C composite electrode systems is consistent with that of the interaction energy, but the ANS is opposite. O2 molecule needs to break through the interaction between ANS and M/C composite electrode to interact with the composite electrode. The results of RDF illustrated that it is difficult for O2 molecule to bond with the active component M in different M/C electrodes in the short-range region, but they form non-bonding interaction in the remote region. On the other hand, ANS and the active component M of different M/C electrodes have bond interaction in the short-range region, and non-bond interaction is greater than bond interaction in the remote region. These results provide theoretical basis for further research and development of electrode materials in chlor-alkali electrolysis industry. [ABSTRACT FROM AUTHOR]

Environmental friendly biocomposites are urgently needed to mitigate the pollution caused by huge consumption of petroleum-based polymers. Renewable carrageenan and polylactic acid (PLA) natural polymers have the potential to replace petroleum-origin polymers. Nevertheless, the carrageenan and PLA themselves inherit poor tensile strength, hydrophobicity and stability. The aim of this study is to underpin the mechanism of synthesis of carrageenan-PLA biocomposite using van't Hoff plot, 1HNMR and density functional theorem simulation. Strong hydrogen bonding was found at 1.88 Å between O atom (carrageenan) and H atom (PLA) and was validated in 1HNMR shifting at 5.3 ppm corresponding to –OH group from PLA. The interaction established in the biocomposite mixed at 50 °C leads to a stronger tensile strength of 75.37 MPa, higher hydrophobicity and thermal stability with highest activation energy of 45.39 kJ/mol. The biocomposite produced from renewable carrageenan-PLA material would be a future replacement for nondegradable plastic as a food packaging material. [ABSTRACT FROM AUTHOR]

Shale oil in China is widely distributed and has enormous resource potential. The pores of shale are at the nanoscale, and traditional research methods encounter difficulty in accurately describing the fluid flow mechanism, which has become a bottleneck restricting the industrial development of shale oil in China. To clarify the distribution and migration laws of fluid microstructure in shale nanopores, we constructed a heterogeneous inorganic composite shale model and explored the fluid behavior in different regions of heterogeneous surfaces. The results revealed the adsorption capacity for alkanes in the quartz region was stronger than that in the illite region. When the aperture was small, solid–liquid interactions dominated; as the aperture increased, the bulk fluid achieved a more uniform and higher flow rate. Under conditions of small aperture/low temperature/low pressure gradient, the quartz region maintained a negative slip boundary. Illite was more hydrophilic than quartz; when the water content was low, water molecules formed a "liquid film" on the illite surface, and the oil flux percentages in the illite and quartz regions were 87% and 99%, respectively. At 50% water content, the adsorbed water in the illite region reached saturation, the quartz region remained unsaturated, and the difference in the oil flux percentage of the two regions decreased. At 70% water content, the adsorbed water in the two regions reached a fully saturated state, and a layered structure of "water–two-phase region–water" was formed in the heterogeneous nanopore. This study is of great significance for understanding the occurrence characteristics and flow mechanism of shale oil within inorganic nanopores. [ABSTRACT FROM AUTHOR]

Three cocrystals of acridine with 2,7-dihydroxynaphthalene (Ia and Ib) in two different polymorphs and 1,5-dihydroxynaphthalene (II) have been synthesized and characterized by single crystal X-ray diffraction method. Two polymorphs of acridine, 2,7-dihydroxynaphthalene cocrystal crystallizes in same space group with different unit-cell parameters. In (Ia) the O–H group form a syn-anti conformation whereas in (Ib) the O–H group form an anti-anti conformation leads to the polymorphic structure of acridine, 2,7-dihydroxynaphthalene. This study reveals that the influence of π⋯π and C–H⋯π interactions in the formation of one-, two-, and three-dimensional supramolecular frameworks when the classical hydrogen bonds such as O–H⋯N and C–H⋯O are limited to discrete motifs. The acridine molecules form continuous π⋯π stacking in the crystal structure of (Ia) and discrete π⋯π stacking in the crystal structure of (Ib) and (II). The conformational flexibility of the substituted hydroxy group has an influence in the supramolecular frameworks of the three-dimensional crystal structure. The intermolecular interaction energy calculation between the molecular pairs has been carried out to study the strength of the interaction and its dependence on the geometrical parameters. [ABSTRACT FROM AUTHOR]

To predict the properties of asphalt binder from a molecular point of view, energy index was introduced into asphalt binder performance analysis. The stability of asphalt binder was evaluated using energy as an indicator. The interaction between styrene-butadiene rubber (SBR) and asphalt binder components was analyzed by simulating the energy change of SBR added to the asphalt binder system. Firstly, molecular models of asphalt binder and SBR-modified asphalt binder (SBRA) were established. The structure of the asphalt binder and SBRA systems at room temperature during the pre-structural optimization were analyzed using molecular dynamics simulations and finally based on Materials Studio 8.0. Subsequently, the energies of the output trajectory file at high temperatures (393 K, 413 K, 433 K, 453 K) were analyzed. Finally, the simulation results were verified by macroscopic testing. The results showed that adding SBR did not significantly affect the structure of asphalt binder. However, the addition of SBR improved the energy of asphalt binder at high temperatures. The stability of the SBRA system was optimal at 433 K when the interaction energy between the asphalt binder and SBR was at a maximum. The largest contribution to the interaction energy was van der Waals energy. It is recommended to store SBRA at a temperature of around 433 K during engineering construction. The interaction of the four components of asphalt binder with SBR followed this order: resin-SBR > asphaltene-SBR > aromatic-SBR > saturate-SBR. The higher content of resin and lower content of saturate served to increase the stability between SBR modifier and asphalt binder. The macroscopic test results were consistent with the simulation results, verifying the accuracy of the simulation. Asphalt binder performance can be improved by changing the asphalt binder component content. Analyzing the stability of asphalt binder using energy index provides a new method to study the performance of asphalt binder. [ABSTRACT FROM AUTHOR]

Accurate estimates of intermolecular interaction energy, ΔE, are crucial for modeling the properties of organic electronic materials and many other systems. For a diverse set of 50 dimers comprising up to 50 atoms (Set50-50, with 7 of its members being models of single-stacking junctions), benchmark ΔE data were compiled. They were obtained by the focal-point strategy, which involves computations using the canonical variant of the coupled cluster theory with singles, doubles, and perturbative triples [CCSD(T)] performed while applying a large basis set, along with extrapolations of the respective energy components to the complete basis set (CBS) limit. The resulting ΔE data were used to gauge the performance for the Set50-50 of several density-functional theory (DFT)-based approaches, and of one of the localized variants of the CCSD(T) method. This evaluation revealed that (1) the proposed "silver standard" approach, which employs the localized CCSD(T) method and CBS extrapolations, can be expected to provide accuracy better than two kJ/mol for absolute values of ΔE, and (2) from among the DFT techniques, computationally by far the cheapest approach (termed "ωB97X-3c/vDZP" by its authors) performed remarkably well. These findings are directly applicable in cost-effective yet reliable searches of the potential energy surfaces of noncovalent complexes. [ABSTRACT FROM AUTHOR]

Here, we introduce the use of ANI-ML potentials as a rescoring function in the host–guest interaction in molecular docking. Our results show that the “docking power” of ANI potentials can compete with the current scoring functions at the same level of computational cost. Benchmarking studies on CASF-2016 dataset showed that ANI is ranked in the top 5 scoring functions among the other 34 tested. In particular, the ANI predicted interaction energies when used in conjunction with GOLD-PLP scoring function can boost the top ranked solution to be the closest to the x-ray structure. Rapid and accurate calculation of interaction energies between ligand and protein also enables screening of millions of drug candidates/docking poses. Using a unique protocol in which docking by GOLD-PLP, rescoring by ANI-ML potentials and extensive MD simulations along with end state free energy methods are combined, we have screened FDA approved drugs against the SARS-CoV-2 main protease (Mpro). The top six drug molecules suggested by the consensus of these free energy methods have already been in clinical trials or proposed as potential drug molecules in previous theoretical and experimental studies, approving the validity and the power of accuracy in our screening method. [ABSTRACT FROM AUTHOR]

Flotation of fine coal particles usually uses oil collectors, but the micromechanisms need to be more defined due to the complex structure and abundant functional groups on the surface of coal bodies [Correction added after first online publication on 16 October 2023: "refined" was changed to "defined" in the first sentence of the article abstract.]. The adsorption spreading behavior and interfacial properties of nonpolar oil drops on flat low‐order coal (LOC) and high‐order coal (HOC) surfaces were investigated in depth using molecular dynamics (MD) simulations, while the effects of different functional groups on LOC surfaces were also considered. The results showed that the contact angle, contact area and interaction energy of oil drops adsorbed on the LOC and HOC surfaces at simulated equilibrium in aqueous environment were 77.68°, 621.49 Å2, −140.94 kcal/mol; 53.98°, 962.14 Å2, and −195.13 kcal/mol, respectively. The smaller the equilibrium contact angle between the oil drops and the surface, the larger the contact area and the larger the absolute value of the interaction energy, the better the spreading effect of the oil drops and the easier the surface is to flotation. Compared with the HOC surface, the oil drops could not displace the water molecules on the LOC surface better and spread poorly on its surface, and the migration rate was higher. This was caused by the abundant functional groups on the surface of LOC. The type of functional group significantly affects the interaction of nonpolar oil drops with hydrophilic surfaces, with the order of adsorption strength being CH3 > COCH3 > OH > COOH. The formation of a dense hydrated film of oil drops on the COOH surface was an important reason for the difficulty of flotation on the LOC surface. MD elucidated the mechanism of action of nonpolar oil collectors on LOC and HOC surfaces, which is a guide for efficient flotation on LOC surfaces. [ABSTRACT FROM AUTHOR]

A molecular model of the interaction between alkaline NaCl solution (Sol) and carbon-supported silver/graphene oxide (Ag/GO/C) composite electrode during oxygen reduction reaction was designed and constructed, and the Molecular dynamics (MD) simulation of the model was carried out. Based on the calculation and analysis of interaction energy (ΔE), diffusion coefficient (D) and radial distribution function (RDF), depending on the type and number of oxygen-containing functional groups of GO, the interaction law between alkaline solution and Ag/GO/C composite electrode was found out, and the interaction mechanism was revealed. The results showed that the interaction force between Sol and Ag/GO/C composite electrodes with 4 different GO structures (GO1, GO2, GO3 and GO4) is mutual attraction at 353 K. The interaction energy between the Sol and the Ag/GO2/C electrode is the highest in numerical terms, and the diffusion capacity of Na+ and Cl– in the Sol is the weakest in the electrode system, indicating that the interaction between the Sol and the Ag/GO2/C electrode prevents the diffusion of solution molecules or ions on the surface of the electrode. The results of RDF showed that O2, Na+ and Cl– in solution within 3.5 Å have no obvious bonding effect with the electrode, while Sol has obvious bonding effect. When the interaction distance is 5–8 Å, O2, Na+, Cl–, Sol in the system and Ag atoms in different composite electrodes all have obvious non-bond interaction, indicating that Sol and the electrode are prone to bond interaction in the short-range region and non-bond interaction in the remote region, while O2, Na+, Cl–, and the electrode are only prone to non-bond interaction in the remote region. In other words, Ag/GO/C composite electrode has bonding and non-bonding effects in the formation of ORR system in alkaline NaCl solution, and it is mainly provided by non-bonding effects. When the number of –O–, –OH, –COOH in GO is 5 : 5 : 2 (GO2), that is, Ag/GO2/C composite electrode is most prone to ORR. This further proved that adding GO to the composite electrode can improve the catalytic performance of the electrode. These results are helpful to provide theoretical support for the research and development of electrodes in electrolytic chlor-alkali industry. [ABSTRACT FROM AUTHOR]

Three homoleptic Hg(S2CNR2)2, for R = ethyl (1), isobutyl (2), and cyclohexyl (3), compounds apparently exhibit a steric-dependent supramolecular association in their crystals. The small group in 1 allows for dimer formation via covalent Hg–S interactions through an eight-membered {–HgSCS}2 ring as the dithiocarbamato ligands bridge centrosymmetrically related Hg atoms; intradimer Hg···S interactions are noted. By contrast, centrosymmetrically related molecules in 2 are aligned to enable intermolecular Hg···S interactions, but the separations greatly exceed the van der Waals radii. The large group in 3 precludes both dimerization and intermolecular Hg···S interactions. Computational chemistry indicates that the potential region at the Hg atom is highly dependent on the coordination geometry about the Hg atom. Intramolecular (1) and intermolecular (2) spodium bonding (SpB) is demonstrated. Even at separations approaching 0.4 Å beyond the sum of the assumed van der Waals radii, the energy of the stabilization afforded by the structure directs SpB in 2 amounts to approximately 2.5 kcal/mol. A natural bond orbital (NBO) analysis points to the importance of the LP(S) → σ*(Hg–S) charge transfer and to the dominance of the dispersion forces and electron correlation to the SpB in 2. [ABSTRACT FROM AUTHOR]

In comparison with conventional macro-systems, two-dimensional sheet-like materials such as aluminum carbide (C3Al) are considered as promising drug delivery systems (DDSs) because of their bioavailability and high adsorption. The surface of two-dimensional materials, which is capable of binding to the molecules of drugs with moderate binding energies, can further improve this adsorption and bioavailability. Hence, the possibility of using C3Al for the delivery of fluorouracil (5FU) is investigated for the first time within this research study. According to the adsorption energy analysis, there is a binding between the molecules of 5FU and C3Al with a moderate interaction energy, which is one of the requirements for a promising DDS. The adsorption energy of 5FU drug on the C3Al monolayer in different complexes is in the range of − 15.67 to − 26.79 kcal/mol, and there is a rise in the dipole moment (DM) of the surface after 5FU is adsorbed. This rise in the DM following the formation of the complex is conducive to improving solubility that is considered a prerequisite in biological systems for drug delivery. There is a reduction in the energy of the highest-occupied molecular orbital (HOMO) of the diene overlaps with the lowest-unoccupied molecular orbital (LUMO) gap of C3Al from 3.45 eV to 2.80 eV following the adsorption of 5FU. According to the results, C3Al seems to be a promising candidate for the delivery of 5FU. The current works provides useful insights into the experimental formulation of DDSs for 5FU based on C3Al. [ABSTRACT FROM AUTHOR]

The new compound 4-hydroxy-1-[(4-nitrophenyl)sulfonyl]pyrrolidine-2-carboxyllic acid was obtained by the reaction of 4-hydroxyproline with 4-nitrobenzenesulfonyl chloride. The compound was characterized using single crystal X-ray diffraction studies. Spectroscopic methods including NMR, FTIR, ES-MS, and UV were employed for further structural analysis of the synthesized compound. The title compound was found to have crystallized in an orthorhombic crystal system with space group P212121. The S1-N1 bond length of 1.628 (2) Å was a strong indication of the formation of the title compound. The absence of characteristic downfield 1H NMR peak of pyrrolidine ring and the presence of S–N stretching vibration at 857.82 cm−1 on the FTIR are strong indications for the formation of the sulfonamide. The experimental study was complemented with computations at the B3LYP/6-311G + + (d,p) level of theory to gain more understanding of interactions in the compound at the molecular level. Noncovalent interaction, Hirsfeld surface analysis and interaction energy calculations were employed in the analysis of the supramolecular architecture of the compound. Predicted ADMET parameters, awarded suitable bioavailability credentials, while the molecular docking study indicated that the compound enchants promising inhibition prospects against dihydropteroate synthase, DNA topoisomerase, and SARS-CoV-2 spike. Herein we present the solid state structure, noncovalent interaction and spectroscopic analysis of a prospective bioactive compound 4-hydroxy-1-[(4-nitrophenyl)sulphonyl]pyrrolidine-2-carboxyllic acid. [ABSTRACT FROM AUTHOR]

We establish the Γ-convergence of some energy functionals describing nonlocal attractive interactions in bounded domains. The interaction potential solves an elliptic equation (local or nonlocal) in the bounded domain and the primary interest of our results is to identify the effects that the boundary conditions imposed on the potential have on the limiting functional. We consider general Robin boundary conditions, which include Dirichlet and Neumann conditions as particular cases. Depending on the order of the elliptic operator the limiting functional involves the usual perimeter or some fractional perimeter. We also consider the Γ-convergence of a related energy functional combining the usual perimeter functional and a nonlocal repulsive interaction energy. [ABSTRACT FROM AUTHOR]

We performed an investigation on urea interacting with hydroxyapatite (HA). The oxygen atoms on HA are either left alone or added with hydrogen to create hydroxyl to resemble the HA surface. Using B3LYP and 3 different basis sets, it was found that urea was able to interact positively with either hydroxyl or non-hydroxyl surface of HA. The Gaussian 09 and Multiwfn software were employed to conduct the calculations. The most favorable interaction has interaction energy of -1.36 eV, which was obtained with the 2 largest basis sets considered, on the pure hydroxyl surface. From the topology analysis on electron density and the non-covalent interaction analysis, it was found that the main attractions between urea and HA were due to the carbonyl oxygen and hydrogen of urea, and hydrogen, oxygen, and calcium on the HA surface. The bond length of newly bonded atoms ranges from 1.62 to 5.18 Å, whereas the energy gap has range between 0.46 to 1.14 eV. All the analysis performed in this study agreed with the results obtained in the formation of favorable interactions and complement previous experimental results that HA can bond with urea molecule. [ABSTRACT FROM AUTHOR]

Modern Density Functional Theory models are now suitable for many molecular and condensed phase studies. The study of noncovalent interactions, a well‐known drawback, is no longer an insurmountable obstacle through design and empirical corrections. However, using empirical corrections as in the DFT‐D methods might not be an all‐in‐one solution. This work uses a simple system, X2‐H2O with X = Cl or Br, with two different interactions, halogen‐bonded (XB) and hydrogen‐halogen (HX), to investigate the capability of current density functional approximations (DFA) in predicting interaction energies with eight different exchange‐correlation functionals. SAPT(DFT) provides, for all the studied cases, better predictions than the widely used supermolecular approach. In addition, the components of the interaction energy suggest where some of the shortcomings originate in each DFA. The analysis of the functionals used confirms that PBE0 and ω‐B97X‐D have a physically correct behavior. Using SAPT(DFT) and PBE0, and ω‐B97X‐D, we obtained the interaction energy of Cl2 and Br2 inside different clathrate cages and satisfactorily compared with wavefunction results; hence, the lower and upper limits of this value are defined: Cl2@512, −5.3 ± 0.3 kcal/mol; Cl2@51262, −5.5 ± 0.1 kcal/mol; Br2@51262, −7.6 ± 1.0 kcal/mol; Br2@51263, −10.6 ± 1.0 kcal/mol; Br2@51264, −10.9 ± 0.8 kcal/mol. [ABSTRACT FROM AUTHOR]

Solid dispersion of poorly soluble APIs is known to be a promising strategy to improve dissolution and oral bioavailability. To facilitate the development and commercialization of a successful solid dispersion formulation, understanding of intermolecular interactions between APIs and polymeric carriers is essential. In this work, first, we assessed the molecular interactions between various delayed-release APIs and polymeric excipients using molecular dynamics (MD) simulations, and then we formulated API solid dispersions using a hot melt extrusion (HME) technique. To assess the potential API–polymer pairs, three quantities were evaluated: (a) interaction energy between API and polymer [electrostatic (Ecoul), Lenard-Jones (ELJ), and total (Etotal)], (b) energy ratio (API–polymer/API–API), and (c) hydrogen bonding between API and polymer. The Etotal quantities corresponding to the best pairs: NPX-Eudragit L100, NaDLO–HPMC(P), DMF–HPMC(AS) and OPZ–HPMC(AS) were −143.38, −348.04, −110.42, and −269.43 kJ/mol, respectively. Using a HME experimental technique, few API–polymer pairs were successfully extruded. These extruded solid forms did not release APIs in a simulated gastric fluid (SGF) pH 1.2 environment but released them in a simulated intestinal fluid (SIF) pH 6.8 environment. The study demonstrates the compatibility between APIs and excipients, and finally suggests a potential polymeric excipient for each delayed-release API, which could facilitate the development of the solid dispersion of poorly soluble APIs for dissolution and bioavailability enhancement. [ABSTRACT FROM AUTHOR]

Globally, the shift towards lignocellulosic biorefinery has opened avenues for valorizing lignin, a majorly accumulated recalcitrant by-product. A targeted lignin processing by ionic liquid-cosolvent mixtures can be an effective biomass conversion strategy. An understanding of lignin-ionic liquid dissolution can enable in designing a significant lignin processing technique to synthesis lignin-based renewable products. Here, we explored the molecular interaction during the dissolution of lignin containing five guaiacyl decamer chains in various (1-Ethyl-3-Methylimidazolium Acetate) EmimOAc-water mixtures using molecular dynamics simulation. The analysis showed that in only water, lignin formed a compact aggregate. Nevertheless, in 50%, 80%, and 100% EmimOAc-water, lignin underwent a segregated chain disentanglement with widespread dynamic motion. A detailed multifaceted analysis of Emim+, OAc− and water distribution on the polar and non-polar sites of lignin units was illustrated. An effective lignin dissolution was observed for 50% and 80% EmimOAc-water systems. The OAc− distribution was stronger around lignin's alkyl chains and alcoholic hydroxy groups. The Emim+ tails significantly impacted the benzene ring, whereas Emim+ heads were distributed around methoxy and hydroxy groups. Altogether, this study explores the lignin dissolution at atomistic level in EmimOAc-water mixtures; these understanding could serve as a cornerstone for engineering new ionic liquid-mediated lignin biorefinery. [Display omitted] [ABSTRACT FROM AUTHOR]

In our present work, we applied Machine Learning approaches to predict potential energy profiles for rare gas dimers as well as for the H 2 molecule. We designed an Artificial Neural Network (ANN) model with one and two layers, with two to eight neurons in each layer, to predict potential energy values. We compared the ANN predicted energy values with the ab initio data and we found an excellent agreement between the actual and predicted values. The root mean squared deviation (RMSD) values for the test data are found to be 0.10, 0.22, 0.03 and 0.47 cm - 1 for He 2 , Ne 2 , Kr 2 and Ar 2 , respectively. Further, we observed that the ANN method is able to fit the potential energy profile for weak van der Waals dimers as well as covalently bound molecules. Application of machine learning approaches to predict the interaction energies for rare gas dimers is tested in this study. Our results show that Artifical Neural Network modeling is able to predict the energies for these van der Waals interactions. [ABSTRACT FROM AUTHOR]

New hydrazone derivate, (1Z,2E)-2-(2-(1-(1,3-dimethyl-2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene)ethyl)hydrazineylidene)-2-(p-tolyl)acetaldehyde oxime (H2L) was synthesized by 5-acetyl-1,3-dimethyl-barbituric acid and p-methyl isonitrosophenylhydrazine. Its molecular and crystal structures were determined by single crystal X-ray analysis. It belongs to triclinic system P-1 space group with a = 7.1722 (3) Å, b = 10.5362 (4) Å, c = 11.7675 (5) Å, α = 98.844 (4)°, β = 98.882 (4)°, γ = 104.330 (4)°, Z = 2 and V = 833.95 (6) Å3. In the molecular structure, the intramolecular N–H···O and N–H···N hydrogen bonds enclose S(6) ring motifs. In the crystal structure, the intermolecular C–H···O and O–H···O hydrogen bonds link the molecules into centrosymmetric dimers, enclosing R22(10) and R44(10) ring motifs, in which they may be effective in stabilization of the structure. The Hirshfeld surface analysis of crystal structure indicates that the most important contributions for crystal packing are from H...H (48.5%), H...O/O...H (23.7%) and H...C/C...H (9.7%) interactions. Hydrogen bonding and van der Waals interactions are the dominant interactions in crystal packing. Computational chemistry indicates that in the crystal, O–H···O and C–H···O hydrogen bond energies are 95.9 and 87.5 kJ mol−1. The evaluation of the electrostatic, dispersion and total energy frameworks indicates that stabilization is dominated via the nearly equal strengths of the electrostatic and dispersion energy contributions. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis and electrochemical characterization of seven ferrocene-terminated self-assembled monolayers (SAMs) on fluorine-doped tin oxide (FTO). The ferrocene surface coverage (Γ Fc) of SAMs was systematically varied and its impact on the kinetics of interfacial electron transfer (ET) was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It was found that as Γ Fc gradually declined from ∼8.0 molecules/nm2 (its maximum value) to ∼2.4 molecules/nm2, the standard ET rate constant (k ET 0 , extracted from CV data) slowly declined from 4.9 s-1 to 4.1 s-1. However, with a further decrease in Γ Fc , k ET 0 abruptly dropped by ∼2.0 s-1 and remained in the range of 2.2–2.7 s-1. The charge transfer resistance (R ct) of SAMs (determined from EIS data) was also found to follow a trend consistent with the one observed for k ET 0. Density functional theory (DFT) calculations confirmed that the observed behavior of ET kinetics as a function of Γ Fc can be attributed to the favorable interaction between adjacent Fc and Ph groups and the stabilization of the Fc HOMO. Besides exploring ET kinetics, Γ Fc data was also employed to evaluate the kinetics of imine condensation reaction at the surface. The corresponding bimolecular rate constant for PhCHO (k PhCHO) was found to be ∼6.2 times greater than that of FcCHO (k FcCHO). [ABSTRACT FROM AUTHOR]

• Hirshfeld surface analysis reveals that hydrogen bonding is essential for both types of crystal packing. • Energy framework analysis confirms crystals stabilized through electrostatic energy contribution. • The higher mechanical stability of the packed crystal was investigated using void analysis. • The non-covalent interaction sites of the molecule are validated through RDG analysis. • The reported piperidine and oxaquinuclidine core compounds exhibit significant binding interaction with the COVID-19 proteins. Two of the title compounds are crystallized in P21/c and monoclinic face groups. Each crystal unit cell has four molecules. There are two piperidine rings: one in the chair conformation and another one in the boat conformation. The piperidine nitrogen in the boat conformation is joined to the oxygen-containing chair conformation piperidine ring to produce the oxaquinuclidine ring (-N-CH 2 O-). Furthermore, because of the steric barrier between rings, all aryl groups are oriented in an equatorial position. The crystal network is maintained through several interactions, including C—H⋯O/N/Cl/π. The crystal void and interaction energy studies gave additional evidence of the strength of the crystal packing and intermolecular linkage. Crystal 3b has less cavity than crystal 3c , indicating that it is densely packed. The dispersion energy contribution dominates the stability, according to the analysis of the electrostatic, dispersion, and total energy frameworks. Reduced density gradient (RDG), electron localization function (ELF), and localized orbital locator (LOL) analysis were used to determine the molecular interaction, electron pair density, and maximally localized orbitals overlapping sites, respectively. This approach reveals that oxaquinuclidine ring steric hindrance and the electron densities throughout the molecules. Density function theory (DFT) provides more evidence for the ring's orientation and the molecules' reactivity. A molecular docking investigation of four essential COVID-19 proteins was carried out using these theoretical ideas. This investigation demonstrates that each protein's reactivity varies; certain proteins have more interaction with high electron density molecules (electron-donating substituent), while others have more interaction with low electron density molecules (electron-withdrawing substituent). The ADMET and drug-likeness investigations reveal that methoxy group substituted molecules perfectly correlate with the required pharmacological characteristics. The cytotoxicity of the five compounds was assessed using the HEK293T cell. [Display omitted] [ABSTRACT FROM AUTHOR]

• Hirshfeld surface analysis reveals that hydrogen bonding is essential for both types of crystal packing. • Energy framework analysis confirms crystals stabilized through electrostatic energy contribution. • The higher mechanical stability of the packed crystal was investigated using void analysis. • The non-covalent interaction sites of the molecule are validated through RDG analysis. • The reported piperidine and oxaquinuclidine core compounds exhibit significant binding interaction with the COVID-19 proteins. Two of the title compounds are crystallized in P21/c and monoclinic face groups. Each crystal unit cell has four molecules. There are two piperidine rings: one in the chair conformation and another one in the boat conformation. The piperidine nitrogen in the boat conformation is joined to the oxygen-containing chair conformation piperidine ring to produce the oxaquinuclidine ring (-N-CH 2 O-). Furthermore, because of the steric barrier between rings, all aryl groups are oriented in an equatorial position. The crystal network is maintained through several interactions, including C—H⋯O/N/Cl/π. The crystal void and interaction energy studies gave additional evidence of the strength of the crystal packing and intermolecular linkage. Crystal 3b has less cavity than crystal 3c , indicating that it is densely packed. The dispersion energy contribution dominates the stability, according to the analysis of the electrostatic, dispersion, and total energy frameworks. Reduced density gradient (RDG), electron localization function (ELF), and localized orbital locator (LOL) analysis were used to determine the molecular interaction, electron pair density, and maximally localized orbitals overlapping sites, respectively. This approach reveals that oxaquinuclidine ring steric hindrance and the electron densities throughout the molecules. Density function theory (DFT) provides more evidence for the ring's orientation and the molecules' reactivity. A molecular docking investigation of four essential COVID-19 proteins was carried out using these theoretical ideas. This investigation demonstrates that each protein's reactivity varies; certain proteins have more interaction with high electron density molecules (electron-donating substituent), while others have more interaction with low electron density molecules (electron-withdrawing substituent). The ADMET and drug-likeness investigations reveal that methoxy group substituted molecules perfectly correlate with the required pharmacological characteristics. The cytotoxicity of the five compounds was assessed using the HEK293T cell. [Display omitted] [ABSTRACT FROM AUTHOR]

• Elevated Ca2+ concentrations (≥50 mg/L) enhanced Microcystis colony formation. • High levels of Ca2+ augmented extracellular polysaccharides secretion and the hydrophobicity of Microcystis cells. • High Ca2+ levels upregulated the genes related to extracellular polysaccharides, energy metabolism, and transmembrane transport in Microcystis aeruginosa. • Colony formation is a result of cellular interaction driven by adhesive extracellular polysaccharides and electrostatic attraction. Colony formation plays a critical role in Microcystis blooms. Previous studies have demonstrated that high Ca2+ concentrations can bring about the rapid aggregation of Microcystis aeruginosa , leading to the formation of colonies with morphologies resembling those observed in the wild over extended periods. However, the mechanisms through which high Ca2+ levels enhance colony formation remain inadequately understood. This study investigated the impact of Ca2+ concentrations on M. aeruginosa colony formation and elucidated the underlying mechanisms. The results indicated that high Ca2+ concentrations (≥50 mg/L) significantly enhanced colony formation, with an increase in colony size observed as Ca2+ concentrations rose within the range of 1–400 mg/L. In addition, the cell surface hydrophobicity and zeta potential increased with Ca2+ concentrations, primarily due to the augmented secretion of extracellular polymeric substances (EPS) and compression of the double electric layer. This decreased interaction energy among Microcystis cells and facilitated colony formation. The energy barrier decreased from 2684.35 KT to 123.64 KT as the Ca2+ concentration rose from 10 mg/L to 400 mg/L, indicating a significantly greater propensity for aggregation in the 400 mg/L Ca2+ group compared to the control. Additionally, this study found that high Ca2+ concentrations upregulated extracellular polysaccharide-, transmembrane transport-, and energy metabolism-related pathways while downregulating photosynthesis-related pathways. This enhanced polysaccharide content in EPS and ultimately promoted colony formation. These findings provide new insights into the role of elevated Ca2+ concentrations in Microcystis colony formation, contributing to the advancements in the knowledge of cyanobacterial bloom mechanisms. [ABSTRACT FROM AUTHOR]

This study investigates the potential of ionic liquids (ILs) as sustainable solvents in ultrasonic-assisted extraction (UAE) to efficiently recover luteolin from peanut shells. Among the range of ILs tested, 1-butyl-3-methylimidazolium tetrafluoroborate stood out as the most effective solvent, achieving the highest extraction yield. Single-factor experiments were conducted to analyze the effects of ultrasonic power, extraction time, extraction temperature, IL concentration, and solid-to-liquid ratio on extraction efficiency. Further optimization of the extraction conditions was performed using response surface methodology and neural network analysis, resulting in a significantly enhanced luteolin yield of 3.71 ± 0.06 mg/g. Interaction energy analyses were conducted to elucidate the interactions between ILs and luteolin, confirming the experimental findings and highlighting the strongest interaction energy between 1-butyl-3-methylimidazolium tetrafluoroborate and luteolin. A kinetic model for luteolin extraction was developed, demonstrating that the extraction process follows a second-order rate model, where the extraction rate is directly proportional to the square of the concentration difference between luteolin and the solvent. The outcomes of this research present an efficient protocol for luteolin extraction and provide novel insights into the application of UAE in extracting natural products. [ABSTRACT FROM AUTHOR]

[Display omitted] • Using DBD plasma to introduce fluorine-containing groups on BNNS surface. • Improving GFRP composites properties significantly with small amounts of F-BNNSs. • Regulating interfacial characteristics to enhance composites insulating properties. The insulation failure of glass fiber-reinforced polymers (GFRP) limits their use in high-voltage insulation fields. In this study, boron nitride nanosheets (BNNS) were prepared using ball-milling and further fluorinated via dielectric barrier discharge (DBD) plasma treatment. The GFRP nanocomposites were fabricated using different filler types and doping concentrations. The test results indicated that fluorinated BNNS (F-BNNS) displays good dispersion and interfacial compatibility, enhances the interfacial bonding strength of the "fiber-matrix-filler" ternary system in GFRP, and reduces the internal defects of materials. In addition, the insulating properties of the composites were related to the filler concentration. Adding a trace amount of F-BNNSs increased the flashover and breakdown voltages of the GFRP by up to 28.77% and 21.62%, respectively. The results of molecular dynamics simulations and trap distribution calculations showed that plasma fluorination of BNNS increases the bandgap and deep trap energy level at the interface. The extremely strong charge-binding ability of the deep traps inhibits continuous charge injection and regulates carrier migration, which improves the insulating properties of the composites. The results of this study provide a novel, environmentally friendly, and efficient solution for improving the insulating properties of GFRP. [ABSTRACT FROM AUTHOR]

• A new useful concept, induced free volume (IFV), is introduced, which is connected directly to the entropic contribution of gas dissolution thermodynamics. • Combination of IFV conception and CH 3 SH/H 2 S interaction with ionic species reasonably explain solubility of these gases in ILs. • EDA calculations were utilized for the first time to illuminate the nature of CH 3 SH/H 2 S interactions with ionic liquids. • OPLS-AA-0.8 yields improved Henry's constants for solubility of CH 3 SH and H 2 S in ILs over previous OPLS versions. Sulfur contaminants in industrial gas streams, such as hydrogen sulfide and mercaptans, must be eliminated due to safety and environmental considerations. Ionic liquids, as a new class of chemical compounds, are an alternative to conventional aqueous alkanolamine solutions currently used in absorption gas treatment processes. In this work, the solubilities of methyl mercaptan (CH 3 SH) and hydrogen sulfide gases in 1-butyl-3-methylimidazolium-based ionic liquids with tetrafluoroborate ([C 4 mim][BF 4 ]), hexafluorophosphate ([C 4 mim][PF 6 ]), trifluoromethanesulfonate ([C 4 mim][OTf]), and bis(trifluoromethylsulfonyl)imide ([C 4 mim][Tf 2 N]) anions have been studied using molecular dynamics (MD) simulation and a recently developed OPLS all-atom (OPLS-AA-0.8) force field. A new concept, the induced free volume, has been introduced in this work, which provides a realistic and precise connection between the thermodynamic entropic contributions to the dissolution process of CH 3 SH and H 2 S in the ionic liquids, on one hand, and the microscopic free/void volume induced as a result of the entrance of a gas solute molecule into the liquid structure, on the other hand. The thermodynamic energetic contributions were correlated to the CH 3 SH/H 2 S interaction with the ionic species of the ionic liquids. Quantum chemical energy decomposition analysis (EDA) was employed to calculate and analyze the binding interaction and nature of CH 3 SH/H 2 S interactions with the ionic species of ionic liquids. It was found that the van der Waals contributions to the interaction of CH 3 SH with ionic liquids are more significant compared to that of H 2 S, while the opposite conclusion could be deduced for the corresponding electrostatic contributions. Both CH 3 SH and H 2 S established equivalent hydrogen bonding interactions with the ionic liquids studied in this work. The diffusion coefficients of the ionic species, as well as the excess chemical potentials and Henry's constants for the dissolution of CH 3 SH and H 2 S in the ionic liquids, were calculated by free energy perturbation technique (FEP) and compared with the MD simulated and experimental data, reported in the literature. It was concluded that the OPLS-AA-0.8 force field yields Henry's constants and diffusivities that are in better agreement with the reliable experimental data corresponding to other OPLS versions reported to date. [ABSTRACT FROM AUTHOR]

• A new useful concept, induced free volume (IFV), is introduced, which is connected directly to the entropic contribution of gas dissolution thermodynamics. • Combination of IFV conception and CH 3 SH/H 2 S interaction with ionic species reasonably explain solubility of these gases in ILs. • EDA calculations were utilized for the first time to illuminate the nature of CH 3 SH/H 2 S interactions with ionic liquids. • OPLS-AA-0.8 yields improved Henry's constants for solubility of CH 3 SH and H 2 S in ILs over previous OPLS versions. Sulfur contaminants in industrial gas streams, such as hydrogen sulfide and mercaptans, must be eliminated due to safety and environmental considerations. Ionic liquids, as a new class of chemical compounds, are an alternative to conventional aqueous alkanolamine solutions currently used in absorption gas treatment processes. In this work, the solubilities of methyl mercaptan (CH 3 SH) and hydrogen sulfide gases in 1-butyl-3-methylimidazolium-based ionic liquids with tetrafluoroborate ([C 4 mim][BF 4 ]), hexafluorophosphate ([C 4 mim][PF 6 ]), trifluoromethanesulfonate ([C 4 mim][OTf]), and bis(trifluoromethylsulfonyl)imide ([C 4 mim][Tf 2 N]) anions have been studied using molecular dynamics (MD) simulation and a recently developed OPLS all-atom (OPLS-AA-0.8) force field. A new concept, the induced free volume, has been introduced in this work, which provides a realistic and precise connection between the thermodynamic entropic contributions to the dissolution process of CH 3 SH and H 2 S in the ionic liquids, on one hand, and the microscopic free/void volume induced as a result of the entrance of a gas solute molecule into the liquid structure, on the other hand. The thermodynamic energetic contributions were correlated to the CH 3 SH/H 2 S interaction with the ionic species of the ionic liquids. Quantum chemical energy decomposition analysis (EDA) was employed to calculate and analyze the binding interaction and nature of CH 3 SH/H 2 S interactions with the ionic species of ionic liquids. It was found that the van der Waals contributions to the interaction of CH 3 SH with ionic liquids are more significant compared to that of H 2 S, while the opposite conclusion could be deduced for the corresponding electrostatic contributions. Both CH 3 SH and H 2 S established equivalent hydrogen bonding interactions with the ionic liquids studied in this work. The diffusion coefficients of the ionic species, as well as the excess chemical potentials and Henry's constants for the dissolution of CH 3 SH and H 2 S in the ionic liquids, were calculated by free energy perturbation technique (FEP) and compared with the MD simulated and experimental data, reported in the literature. It was concluded that the OPLS-AA-0.8 force field yields Henry's constants and diffusivities that are in better agreement with the reliable experimental data corresponding to other OPLS versions reported to date. [ABSTRACT FROM AUTHOR]

Polyacrylamide hydrogels are widely used in medicine, petrochemical, water treatment and other fields, among which polyacrylamide hydrogels play an important role in oilfield Profile control and water shutoff and enhanced oil recovery, however, there are few reports on the effect of different inorganic salt solutions on the properties of SiO 2 composite hydrogel. In this paper, a cross-linked SiO 2 composite hydrogel was constructed using Materials Studio software for the first time, and its structure and properties in inorganic salt aqueous solutions were studied. The results show that the addition of inorganic salts can weaken the interaction between water molecules and hydrogels, and this effect is minimal in calcium chloride solution. The radial distribution function shows that there are strong hydrogen bonds between nitrogen and oxygen atoms in the amide group and water molecules, but there are van der Waals forces between oxygen and water atoms, and the addition of inorganic salts will enhance the hydration of nitrogen atoms in the amide group and the interaction between monovalent ions and amide groups was greater than that between bivalent ions. At the same time, the addition of inorganic salts can also enhance the diffusion ability of water molecules and the fluidity of polymer chains. Among the four inorganic salt solutions, Calcium chloride solution has the least effect on the polymer chain and the cross-linked SiO 2 composite hydrogel has the best expansion performance in calcium chloride solution, which is basically consistent with the experimental results, this has a potential application prospect in the reservoir with high calcium content for profile control and water plugging and enhanced oil recovery. [Display omitted] • Cross-linked SiO 2 composite hydrogel in inorganic salt solution is established. • Effects of different inorganic salt solutions on the interaction energy of composites each component are studied. • Both nitrogen and oxygen atoms in amide groups have strong hydrogen bonds with water molecules. • Main controlling factors affecting the fluidity of cation and polymer chains are revealed. • SiO 2 composite hydrogel has the best expansion performance in calcium chloride solution. [ABSTRACT FROM AUTHOR]

The membrane fouling induced by algal extracellular organic matter (EOM) remain a bottleneck in restricting ultrafiltration (UF) application during harmful algal-water treatment. In current study, the application of heat-activated peroxydisulfate (PMS) and coagulation (Aluminum chlorohydrate, PACI) on membrane fouling behavior during Chlorella -laden water treatment was investigated. The membrane fouling mechanism was analyzed using the extended Derjaguin-Landau-Verwey-Over-beek (XDLVO) theory. The results revealed that separated heat-activated PMS could enhance the filtration flux of EOM at high PMS does >0.2 mM, whereas the membrane fouling was further alleviated by combined heat-activated PMS (0.2–1.0 mM) and PACI (20 mg/L) treatment, especially at low PMS dose. Combined heat-activated PMS and PACI pretreatment could effectively increase the adhesive repulsion between membrane and foulants and reduce the cohesion free energies between organic foulants than those by separated heat-activated PMS treatment, making the initial filtration flux reduced and the cake layer looser. Moreover, the organic foulants of proteins, polysaccharides, and humic-like organics were removed. Cake formation was the major fouling mechanism when EOM was treated with/without separated heat-activated PMS treatment, whereas the membrane fouling mechanism was changed from cake layer formation to pore blocking after combined heat-activated PMS and PACI treatment. Overall, this research provided a feasible method in membrane fouling control during Chlorella -laden water treatment. [Display omitted] • Integrated heat-PMS and PACI on membrane fouling behavior was investigated during Chlorella -laden water treatment. • Membrane fouling mechanism was analyzed using XDLV theory. • Membrane fouling mechanism was changed after heat-PMS and PACI treatment. [ABSTRACT FROM AUTHOR]

Here, we investigate the performance of "Accurate NeurAl networK engINe for Molecular Energies" (ANI), trained on small organic compounds, on bulk systems including non‐covalent interactions and applicability to estimate solvation (hydration) free energies using the interaction between the ligand and explicit solvent (water) from single‐step MD simulations. The method is adopted from ANI using the Atomic Simulation Environment (ASE) and predicts the non‐covalent interaction energies at the accuracy of wb97x/6‐31G(d) level by a simple linear scaling for the conformations sampled by molecular dynamics (MD) simulations of ligand‐n(H2O) systems. For the first time, we test ANI potentials' abilities to reproduce solvation free energies using linear interaction energy (LIE) formulism by modifying the original LIE equation. Our results on ~250 different complexes show that the method can be accurate and have a correlation of R2 = 0.88–0.89 (MAE <1.0 kcal/mol) to the experimental solvation free energies, outperforming current end‐state methods. Moreover, it is competitive to other conventional free energy methods such as FEP and BAR with 15‐20 × fold reduced computational cost. [ABSTRACT FROM AUTHOR]

Clay particle deposition in porous media is critical in many geotechnical applications that rely on filtration. The deposition of particles in the filter medium can result in clogging, which causes a reduction in the hydraulic conductivity of the filter medium. Particle attachment and detachment are a function of the interaction energy between clay particles and the filter bed material, which is frequently sand. These mechanisms are governed by the size of the clay particles as well as the solution chemistry. Batch kinetic adsorption tests were carried out to investigate the impact of ionic strength on the attachment of kaolinite to silica sand grains. Significant attachment of kaolinite was observed as ionic strength of the pore fluid increased and as the size of silica particles decreased. The short-term deposition of clay particles was not sensitive to ionic strength; however, in contrast, long-term deposition was a strong function of ionic strength. [ABSTRACT FROM AUTHOR]

Methods: The intermolecular interactions between the heavy-atom analogues of acetylene T2H2 (T = Si, Ge, Sn, Pb) and HCN have been investigated by theoretical calculations at the CCSD(T)/aug-cc-pVTZ//MP2/aug-cc-pVDZ level. Results: The global energy minimum of T2H2 is the butterfly structure A, and another energy minimum is the planar structure B. Both structures A and B exhibit the dual behavior when binding with HCN. The various hydrogen bond (HB), dihydrogen bond (DB) and tetrel bond (TB) complexes can be found according to the MEP maps of T2H2. One TB and three HB complexes formed between structure A and HCN can be located for Si2H2 and Ge2H2. One TB, two HB and one DB complexes formed between structure A and HCN can be located for Sn2H2 and Pb2H2. Four TB and one HB complexes formed between structure B and HCN can be located for all the T2H2. The geometries and binding strengths of the complexes are compared and analyzed. Conclusions: The interactions in these complexes are generally weak, and the interaction energies of these complexes range from −0.53 to −8.23 kcal/mol. The interaction energies of the TB complexes are larger than those of the corresponding HB and DB complexes for structure A···HCN systems. The relative binding strength of the four TB complexes exhibits different order for different structure B···HCN systems, which is consistent with the MEP maps of the isolated monomers. [ABSTRACT FROM AUTHOR]

To explore the influence of freezing and thawing on drainage behaviour for porous asphalt pavement (PA), molecular dynamics simulation was applied to study the interaction between asphalt and water. Based on the establishment and verification of micro models for asphalt (virgin and aged) and water (ice, ice–water mixture and water), the micro behaviour of interfacial transition zone was intuitively observed. Combined with the multi-gradient experiment results, the micro influence mechanism of freezing and thawing on drainage behaviour of porous asphalt pavement was revealed. The results show that the interaction energy of asphalt–water changes with the occurrence of freeze–thaw. The interaction energy (attraction) between aged asphalt and water is enhanced, which leads to water-induced distress more easily. In addition, with the occurrence of freeze–thaw, the relative concentration of hydrogen atoms at the interfacial transition zone gradually increases, while the fluctuation of carbon atoms increases. The results provide a micro-mechanism for the study of drainage behaviour of porous asphalt pavement under freezing and thawing, which has certain theoretical significance and practical value. [ABSTRACT FROM AUTHOR]

Molecular structures of four 6-chloro-coumarins have been optimized using DFT/B3LYP method. The energy of the HOMO and LUMO has been predicted. Lattice energy analysis (based on CLP-PIXEL module) in case of each structure indicates that the crystal packing stability is mainly derived by C–H...O and π...π type interactions. Besides this, the intermolecular interactions of the type C–H...Cl, C–H...π, C–Cl...π and C–Cl...O also exist in the crystal structures. Quantitative analysis of each intermolecular interaction using 3D-Hirshfeld surfaces and corresponding 2D-fingerprint has been carried out. [ABSTRACT FROM AUTHOR]

We analyse two‐component electroneutral systems of classical finite‐sized macroions with the charge Z ≫ 1 and point oppositely charged microions with a unit charge. The article deals with a modification of the Debye–Hückel plus hole approximation when nonlinear screening effect is taken into account in asymmetric complex plasmas. We calculate the interaction energy in the Poisson–Boltzmann plus hole approximation considering the interaction of all particles (both inside and outside the hole). This energy has a greater value than some previous results. In addition, we subdivide all hole microions into two types, free microions and bound ones, and show a significant reduction of an effective macroion charge Z* in comparison with its initial charge Z due to the nonlinear screening by a thin high‐concentration bound microions envelope. We demonstrate that this procedure increases the Debye radius that takes the screening by microions and macroions outside the hole into account. [ABSTRACT FROM AUTHOR]