Intermolecular Interaction Energies Research Articles

Synthesis of phenazone based carboxamide under thiourea reaction conditions. Molecular and crystal structure, Hirshfeld surface analysis and intermolecular interaction energies

Considering the added advantage of active pyrazolone pharmacophore and phenazone drug itself with associated medicinal applications, we herein aim to derivatize this potent active non-steroidal anti-inflammatory drug (NSAID) to its thiourea derivative for enhanced biological potential. Thiourea reaction conditions were utilized to make use of active amino group of phenazone drug in reaction with furan-2-carbonyl isothiocyanate for formation of corresponding aroyl thiourea derivative. However, on detailed single crystal XRD, spectroscopic and analytical investigations, it become apparent the formation of phenazone-carbonothioyl carboxamide rearranged product. The novel compound was characterized by spectroscopic methods and its crystal structure was determined by single-crystal X-ray diffraction. In the solid, the pseudo-syn conformation is observed for the amide/thioamide groups, with the C=O and C=S double bonds oriented mutually parallel, favoring the occurrence of intramolecular O2···S1 chalcogen bond, as characterized by Atoms in Molecules (AIM) topological analysis. According to quantum chemical calculations, the pyrazolone group favors the formation of a dimer (Etot = -56.7 kJ/mol) which is mainly stabilized by C-H···O hydrogen bonds and π···π stacking interactions between the pyrazole and furan rings. The solid-state structure was analyzed through Hirshfeld surface analysis, including the evaluation of the different energy frameworks, indicating that H···O hydrogen bonds and H···S/S···H contacts are the main electrostatic interactions. These studies are complemented with DFT calculations (B3LYP-D3/def2-TZVP) and a combination of QTAIM/NCIplot analyses disclosing that the H-bonding and π···π stacking interactions dominate the crystal packing.

Structural, Hirshfeld surface and three-dimensional inter-action energy studies of 2-(6-iodo-4-oxo-3,4-di-hydro-quinazolin-3-yl)ethane-sulfonyl fluoride.

In the crystal, mol-ecules of the title compound, C10H8FIN2O3S, are connected through C-H⋯N and C-H⋯O hydrogen bonds, I⋯O halogen bonds, π-π stacking inter-actions between the benzene and pyrimidine rings, and edge-to-edge electrostatic inter-actions, as shown by the analysis of the Hirshfeld surface and two-dimensional fingerprint plots, as well as inter-molecular inter-action energies calculated using the electron-density model at the HF/3-21 G level of theory.

МОЛЕКУЛЯРНАЯ СТРУКТУРА И РАДИОЗАЩИТНАЯ АКТИВНОСТЬ ПРОИЗВОДНЫХ АМИНОЭТИЛТИОСУЛЬФАТОВ И АМИНОТИОЛОВ

An analysis of the relationship of radioprotective properties in the series of derivatives of S-2-aminoethylthiosulphates and S-2-aminothiols with their electronic characteristics and physicochemical parameters was performed. The result indicates the existence of a statistically significant relationship between the radioprotective activity and the value of the parameters of the radioprotector molecule: the lower free molecular orbital, the product of the ionization potential and polarizability, and the distribution coefficient in the octanol-water system. In the process of implementing the protective properties of a radioprotector, the ability of the drug to participate in the formation of charge transfer complexes for temporary inhibition of biochemical processes is of great importance. It was shown that the protective effect correlates with the ability of these compounds to participate in the electron transfer process, the energy of intermolecular interaction in the drug-damaged biomolecule system, and the transport properties of radioprotector molecules in the body. It was established that protection can be carried out through the formation of complexes in which molecules of S-2-aminoethylthiosulphate and S-2-aminothiol derivatives act as ligands, and the protective effect increases with an increase in the bond of the complexes and the mobility of the radioprotector molecules.

Intermolecular interactions in clusters of ethylammonium nitrate and 1-amino-1,2,3-triazole.

The intermolecular interaction energies, including hydrogen bonds (H-bonds), of clusters of the ionic liquid ethylammonium nitrate (EAN) and 1-amino-1,2,3-triazole (1-AT) based deep eutectic propellants (DeEP) are examined. 1-AT is introduced as a neutral hydrogen bond donor (HBD) to EAN in order to form a eutectic mixture. The effective fragment potential (EFP) is used to examine the bonding interactions in the DeEP clusters. The resolution of the Identity (RI) approximated second order Møller-Plesset perturbation theory (RI-MP2) and coupled cluster theory (RI-CCSD(T)) are used to validate the EFP results. The EFP method predicts that there are significant polarization and charge transfer effects in the EAN:1-AT complexes, along with Coulombic, dispersion and exchange repulsion interactions. The EFP interaction energies are in good agreement with the RI-MP2 and RI-CCSD(T) results. The quasi-atomic orbital (QUAO) bonding and kinetic bond order (KBO) analyses are additionally used to develop a conceptual and semi-quantitative understanding of the H-bonding interactions as a function of the size of the system. The QUAO and KBO analyses suggest that the H-bonds in the examined clusters follow the characteristic hydrogen bonding three-center four electron interactions. The strongest H-bonding interactions between the (EAN)1:(1-AT)n and (EAN)2:(1-AT)n (n = 1-5) complexes are observed internally within EAN; that is, between the ethylammonium cation [EA]+ and the nitrate anion ([NO3]-). The weakest H-bonding interactions occur between [NO3]- and 1-AT. Consequently, the average strengths of the H-bonds within a given (EAN)x:(1-AT)n complex decrease as more 1-AT molecules are introduced into the EAN monomer and EAN dimer. The QUAO bonding analysis suggests that 1-AT in (EAN)x:(1-AT)n can act as both a HBD and a hydrogen bond acceptor simultaneously. It is observed that two 1-AT molecules can form H-bonds to each other. Although the KBOs that correspond to H-bonding interactions in [EA]+:1-AT, [NO3]-:1-AT and between two 1-AT molecules are weaker than the H-bonds in EAN, those weak H-bond networks with 1-AT could be important to form a stable DeEP.

InsilicoScreening of Pentacyclic Triterpenoids against Vascular Dementia Target's.

Vascular dementia (VaD) accounts to 30% of cases and is predicted as second most common form of dementia after Alzheimer's disease by WHO. Earlier studies reported that plant-derived pentacyclic triterpenoids possess a wide range of pharmacological activities but these compounds are not extensively studied for their neuroprotective potential against VaD. This in silico approach was designed to screen 20 pentacyclic triterpenoid plant compounds against known targets of VaD using Flare software. S-Adenyl homocysteine hydrolase, Acetylcholinesterase, and Butyrylcholinesterase were selected as important VaD targets, and various parameters like intermolecular interaction energies, binding energy, and dock scores were analyzed and compared between selected ligands. Our results showed that Ursolic acid has lowest binding energy when docked with most of the target proteins, and among all 20 pentacyclic triterpenoids studied, onlythree ligands Betulinic acid, Ambolic acid, and Madecassic acid, showed better binding energy scores, and they can be shortlisted as lead compounds to further study their therapeutic potential against VaD using in vitro and in vivo animal models.

Theoretical study of the tuning role of β-methylthio or β-methylselenyl on the charge-transport properties of acenedithiophenes derivatives.

To date, the manipulation of intermolecular nonconjugation interactions in organic crystals is still a great challenge due to the complexity of weak intermolecular interactions. Here we designed molecules substituted by β-methylselenyl on naphtho[1,2-b:5,6-b']dithiophene and anthra[2,3-b:6,7-b']dithiophene, respectively (anti-β-MS-NDT, anti-β-MS-ADT), which together with anti-β-MS-BDT synthesized experimentally all exhibited 2D brickwork π-stacking. Moreover, their maximum molecular carrier mobilities reached 3.30 and 16.46 cm2 V-1 s-1. These results indicated that the substitution of β-methylselenyl could be a strategy to directionally adjust the parent herringbone stacking into 2D brickwork π-stacking. Hirshfeld surface analysis and symmetry-adapted perturbation theory (SAPT) were used to investigate the nonconjugated interactions in the pitched π-stacking formed by the β-methylthio-substituted acenedithiophene derivatives and the 2D brickwork π-stacking of the β-methylselenyl-substituted ones; wherein, the steric hindrance caused by the introduction of the substituents promoted Csp2-Csp2⋯π interactions to replace Csp2-H⋯π to stabilize the face-to-face stacking. Moreover, by calculating the decomposition energy of the intermediate state model of the molecular stacking mode that may exist in the replacement conversion process, it was found that the energy of this intermediate state was larger than that of the actual ones, finally confirming the inevitability of the actual existence in this stacking. In addition, because of the reduction in intensity of the special vibration modes, it could be found that the β-methylselenyl substitution showed better phonon assistance than β-methylthio substitution in terms of dynamic disorder. This study is a further step toward fully understanding the relationship between intermolecular interactions and regulation of the molecular stacking.

Application of a biodegradable poly(butylene adipate-co-terephthalate) membrane for phenol pervaporation recovery.

In the field of membrane separation, the environmental concerns caused by spent membranes are becoming increasingly serious, which contradicts the concept of sustainable development. Based on this, a biodegradable poly(butylene adipate-co-terephthalate) (PBAT) membrane was used for the first time in the pervaporation separation of phenol, a high boiling point organic compound (HBOC). By using the PBAT membrane, outstanding separation efficiency was achieved, and environmental pollution and disposal issues were also avoided. The separation process and mechanism of the PBAT membrane were systematically studied through the experiment together with molecular dynamics (MD) simulation. The swelling experiment and intermolecular interaction energy calculation demonstrated that the PBAT membrane had a strong affinity for phenol. Further simulation concluded that higher phenol concentration increased the number of hydrogen bonds so that the membrane was more greatly swollen. Meanwhile, the simulations on the adsorption, diffusion and permeation predicted that the PBAT membrane had excellent separation performance for phenol. Besides MD simulation, the influences of feed concentration and temperature on pervaporation performance were also investigated by experiment. The results showed that the flux of each component increased with the feed concentration. This phenomenon was attributed to the preferential adsorption of phenol by the PBAT membrane, which resulted in large free volumes and cavities within the membrane, accelerating the diffusion of molecules. In addition, it was found that the optimal operating temperature was 333 K with the best separation performance. This study confirms that the biodegradable PBAT membrane is valuable for the recovery of high boiling point organic compounds (HBOCs) such as phenol.

Investigating the Structural and in-Silico Bioactive Properties of a Newly Synthesized Schiff Base Compound through Experimental and Computational Approaches

A new Schiff base compound, (E)–2–[(2–bromophenylimino)methyl]–4,6–dichloro–3–methoxyphenol, was obtained from the condensation reaction of 3,5–dichloro–2–hydroxy–6–methoxybenzaldehyde and 2–bromoaniline in ethanol. Single-crystal XRD studies revealed that the planarity in 3D molecular structure with 5.2° between the two aromatic rings and the crystal packing pattern which is formed by weak intermolecular C―H···O hydrogen bonds and π···π interactions. Geometry optimizations with Gaussian and Slater-type basis sets revealed the molecule's planarity to be significantly distorted at 40.2°. Fingerprint plots and energy frameworks were generated using the Hirshfeld surface analysis approach to better comprehend crystal packing and show the quantity of intermolecular interaction energies. To confirm the suitability of the chosen computational methods, root mean square errors in bond lengths and angles were calculated for the two calculated structures and the experimental structure. Intramolecular charge transfer effects on the molecule have been investigated with the scan and NBO calculations using Gaussian-type basis sets, which were time-saving basis sets in the geometry optimizations. Using experimental FT–IR/UV spectra and calculated ones, molecular electronic configuration outlined in solid-state and solvent media. Molecular docking studies were carried out to examine the compound's potential inhibitory activities against hMAOB protein, and binding energy was found as -8.84 kcal/mol.

Decoding the infrared spectra changes upon formation of molecular complexes: the case of halogen bonding in pyridine⋯perfluorohaloarene complexes.

A recently developed computational scheme is employed to interpret changes in the infrared spectra of halogen-bonded systems in terms of intermolecular interaction energy components (electrostatic, exchange, induction, dispersion) taking pyridine⋯perfluorohaloarene complexes as examples. For all complexes, we find a strong linear correlation between the different terms of the interaction-induced changes of the IR band associated with an intermolecular halogen bond stretching mode and the corresponding terms of the interaction energy, which implies that the interaction components play similar roles in both properties. This is not true for other vibrational modes localized in one of the monomers studied here, for which the corresponding interaction-induced changes in IR bands may present a completely different decomposition than the interaction energy.

A Quinoline-Based Fluorescent Labelling for Zinc Detection and DFT Calculations

8-carboxamidoquinoline derivatives were gradually investigated as zinc's label in resolving weak water solubility, poor membrane permeability, and difficulty measuring free Zn2+ ion in cells quantitatively. The potential of 2-oxo-2-(quinolin-8-ylamino)acid (OQAA) as zinc's label was prepared and characterized spectroscopically. Theoretical and experimental data of OQAA were compared and discussed. The optimized molecular structure, molecular orbital of HOMO-LUMO, energy band gaps, and molecular electrostatic potential (MEP) of OQAA were carried out using the DFT method with Becke-3-Parameter-Lee-Yang-Parr (B3LYP) and 6-31G(d,p) basis set. The intermolecular interaction energy of OQAA-Zn is calculated by using the hybrid method of GEN with a basis set of LANL2DZ for Zn2+ ion and DFT/6-31G(d,p) for OQAA ligand. OQAA exhibited remarkable and excellent fluorescence enhancement selective and qualitatively only for Zn2+ than other metal cations tested (Fe2+, Cu2+, Co2+, Ni2+, Hg2+, Cd2+) under a long wavelength. Job's plot and 1H NMR titrations indicate OQAA-Zn2+ has a binding ratio at 1:1 stoichiometry (M1L1). Substantial shifting of amide N-H proton to higher chemical shift and intensity of the proton peak of N-H amide decrease abruptly implies that Zn2+ is binding to an amide. These changes confirmed interactions among the ligand OQAA and metal Zn2+ ion. As a result of the benefits discussed, OQAA could effectively and selectively optimize and fabricate for Zn2+ sensors.

Determination of Intermolecular Interactions of Nicotinamide Liganded Complexes of Co(II), Cu(II), Ni(II) and Zn(II) 4-Formilbenzoates by Hirshfeld Surface Analysis and Investigation of Interaction Energies.

CrystalExplorer program is a program that has been used frequently in the field of theoretical chemistry in recent years and its popularity has increased. First of all, Hirshfeld surface analysis of molecules can be done in this program. Thanks to Hirshfeld surface analysis, intermolecular interactions and their contributions to the crystal surface can be determined. In this study, Hirshfeld surface analyzes and energy frameworks of nicotinamide complexes of Co(II), Cu(II), Ni(II) and Zn(II) 4-formylbenzoate were investigated. Dnorm index, shape index, curvature index and 2D fingerprint graphs were examined for all complexes. In addition, the intermolecular interaction energies of the complexes were calculated using the CE-B3LYP/6-31G (d,p) and CEHF/3-21G energy models. As a result of all these, it was seen that the most important interaction in the four isostructured complexes was H...H interactions.
 According to Hirshfeld surface analysis and energy frameworks, O-H...O and N-H...O hydrogen bonds and π•••π stacking and C−H••π interaction energies are seen as the most important interaction types in the crystal structure.

Effects of Atypical Hydrogen Bonds and π-π Interactions on Nonlinear Optical Properties: Dimers of Triangular Structures Based on Perylene, Naphthalene, and Pyromellitic Diimides.

Nonlinear optical (NLO) materials have become important materials in the field of high-speed optical devices due to the changes in light absorption and refraction caused by the photoelectric field. Compounds tend to exist as aggregates rather than single molecules, so intermolecular interactions are crucial to the nature of aggregates. Therefore, to study the effects of intermolecular interactions on nonlinear optical properties, we use a dimer simplified model and adopt the methods of controlling variables, which are the different intermolecular interactions resulting from the different stacking patterns of dimers based on the same monomer structures (2PMDI-1NDI and 2NDI-1PDI). It is found that compared with dimers involving π-π interactions, dimers involving C-H···O interactions have shorter intermolecular distances, larger intermolecular interaction energies, and smaller highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy gaps. Moreover, the C-H···O interactions are more conducive to the intermolecular charge transfers and more beneficial for increasing the nonlinear optical response values of aggregates with respect to π-π interactions. This work provides an important basis for the influence of intermolecular interactions on nonlinear optical properties.

Tetrel Bonding in Anion Recognition: A First Principles Investigation

Twenty-five molecule-anion complex systems [I4Tt···X-] (Tt = C, Si, Ge, Sn and Pb; X = F, Cl, Br, I and At) were examined using density functional theory (ωB97X-D) and ab initio (MP2 and CCSD) methods to demonstrate the ability of the tetrel atoms in molecular entities, I4Tt, to recognize the halide anions when in close proximity. The tetrel bond strength for the [I4C···X-] series and [I4Tt···X-] (Tt = Si, Sn; X = I, At), was weak-to-moderate, whereas that in the remaining 16 complexes was dative tetrel bond type with very large interaction energies and short Tt···X close contact distances. The basis set superposition error corrected interaction energies calculated with the highest-level theory applied, [CCSD(T)/def2-TZVPPD], ranged from -3.0 to -112.2 kcal mol-1. The significant variation in interaction energies was realized as a result of different levels of tetrel bonding environment between the interacting partners at the equilibrium geometries of the complex systems. Although the ωB97X-D computed intermolecular geometries and interaction energies of a majority of the [I4Tt···X-] complexes were close to those predicted by the highest level of theory, the MP2 results were shown to be misleading for some of these systems. To provide insight into the nature of the intermolecular chemical bonding environment in the 25 molecule-anion complexes investigated, we discussed the charge-density-based topological and isosurface features that emanated from the application of the quantum theory of atoms in molecules and independent gradient model approaches, respectively.

Cyclic Dimers of 4-n-Propyloxybenzoic Acid with Hydrogen Bonds in the Gaseous State.

A comprehensive study of saturated vapors of 4-n-propyloxybenzoic acid (POBA) by gas electron diffraction (GED) and mass spectrometric (MS) methods supplemented by quantum chemical (QC) calculations was carried out for the first time. An attempt was made to detect dimeric forms of the acid in the gaseous state. It has been established that at the temperature of GED experiment, vapor over a solid sample contains up to 20 mol.% of cyclic dimers with two O-H...O hydrogen bonds. The main geometrical parameters of gaseous monomers and dimers of POBA are obtained. The distance r(O…O) = 2.574(12) Å in the cyclic fragment of the gaseous dimer is close to that in the crystal structure (2.611 Å). In the mass spectrum of the POBA recorded the ions of low intensity with a mass exceeding the molecular mass of the monomer were detected. The presence of ions, whose elemental composition corresponds to the dissociative ionization of the dimer, confirms the results of the GED experiment on the presence of POBA dimers in the gas state. The results of GED studies of acetic acid, benzoic acid, and POBA were compared. It is shown that the COOH fragment saves its geometric structure in monomers, as well as the COOH...HOOC fragment with two hydrogen bonds in dimers of different acids. The intermolecular interaction energy in considered acid dimers was estimated using QC calculations (B97D/6-311++G **). The significant value of last (>84 kJ/mol) is the reason for the noticeable presence of dimers in the gas phase.

η3-allyl-Pd(II) complexes of 2-, 3- and 4-pyridylmethyl-coumarin esters

A series of 2-, 3- and 4-pyridylmethyl-coumarin esters ligands (1–3) and their η3-allyl palladium complexes (1-Pd–3-Pd) have been designed, synthetized, and characterized. NMR analysis of compounds 1-Pd–3-Pd indicated the presence of the allyl fragment. The molecular structures of 2, 3 and 1-Pd were determined by X-ray crystallographic analysis. The molecular structure of 1-Pd reveals that coumarin ligand (2) is coordinated to the palladium center via a monodentate fashion through the nitrogen atom of the pyridinyl fragment while, the allyl group is binding via a η3 fashion in an overall square-planar geometry completed with a chloride atom. The crystal packing is stabilized by a variety of weak intermolecular conventional and non-conventional interactions involving C–H–O/N hydrogen bonds, π–π and C–H–π interactions, which have been analyzed by Hirshfeld surface and non-covalent interactions analysis. The intermolecular interaction energies were explored using an energy framework analysis, which revealed that π–π and C–H–π interactions serve as the primary building blocks in these crystal packing.Graphical abstract

Non-covalent interactions towards 2-(4-(2,2-dicyanovinyl) benzylidene)malononitrile packing polymorphism due to solvent effect. Experimental and theoretical spectroscopy approach

Two polymorphs of 2-(4-(2,2-dicyanovinyl)benzylidene)malononitrile (I) were obtained by slow evaporation in acetone (Ia) and acetonitrile (Ib). These two polymorphic forms were analyzed by single-crystal XRD, which revealed both crystallized in the monoclinic crystal system and space group P21/n with Z = 2 (Z′= 0.5). Also, the SCXRD analysis evidenced that in the solvent-induced packing polymorphism; the Ia compound molecules are arranged in a slipped stacking pattern formed through the π···π interactions; while Ib molecules are arranged in a herringbone pattern stabilized by the intermolecular CH···N interactions. Packing polymorphism affects the fluorescence; for Ia crystals, the maximum emission wavelength was at 500 nm and for Ib was at 482 nm. The molecule structure features two C–C bonds with free rotation allowing conformational variation between polymorphs, and the principal difference is in molecular packing due to intramolecular and intermolecular interactions. The intermolecular interaction energies for the molecular dimers were obtained by the PIXEL method. The total lattice energy estimated using PIXELC module, was 32.71 and 34.03 kcalmol−1, for Ia and Ib, respectively; Ib showed a lower contribution of %Edis towards the total stabilization energy and might be due to a more significant number of stacking interactions formed in the crystal packing. Hirshfeld surface (HS) analysis and 2D-fingerprint plots were used to evaluate the relative contribution of non-covalent interactions (NCI) towards the crystal packing. The topology parameters suggested that the intermolecular interactions are weaker, and purely van der Waals and NCI plots were used to visualize the nature of non-covalent interactions. The complete assignments of all vibrational modes computed with potential energy distributions (PEDs) using the VEDA were in good agreement with experimental values; the difference is for the CN-stretching bands caused for the intramolecular interactions indicating possible charge transfer (CT). Natural bond orbital (NBO) analysis and electrostatic potential surfaces (MEPS) were performed to estimate the donor and acceptor sites in the molecule. Additionally, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies and absorption wavelength were calculated by the time-dependent DFT approach. Using 1H and 13C chemical shifts to determine interactions before crystallization. The physicochemical characterization for both Ia and Ib did not show important differences using analytical techniques FT-IR, NMR, DSC/TGA, and PXRD.

Synthesis, Characterization, Crystal Structure and Computational Study of Third‐Order NLO Properties of Schiff bases

AbstractThe current study involves the synthesis of two azomethine compounds, (E)‐2‐((6‐nitrobenzo[d][1,3]dioxol‐5‐yl)methylene)amino)phenol (2AP6NO) and (E)‐2‐((4‐ethylbenzylidene)amino)phenol (2AP4ETH), as well as their theoretical investigations. The synthesized azomethine compounds were then characterized by combustion analysis (CHN), FT‐IR, NMR (1H and 13C), and single crystal X‐ray diffraction (SC‐XRD) analysis. The SC‐XRD study confirmed the enol tautomeric form of 2AP6NO as well as 2AP4ETH. The strong and comparatively weak intermolecular interactions were elaborated by Hirshfeld surface analysis. For both compounds, intermolecular interaction energies between the pair of molecules, energy framework, and void analysis were calculated to visualize the three‐dimensional topology of the crystal packing. Additionally, quantum chemical computations were also utilized to study the optical and nonlinear optical (NLO) response. The molecular geometries were optimized at the M06‐2X/6‐311G* method and equated to their respective experimental counterparts. The third‐order NLO polarizabilities were also calculated at the same level of theory. The calculated average third‐order NLO polarizabilities were 62.55×10−36 esu and 55.08×10−36 esu, respectively, predicting the modest behavior of the above compounds when displaying NLO properties.

Mechanistic insight into separation of benzene and cyclohexane by extractive distillation using deep eutectic solvent as entrainer

In this work, a technical scheme for separation of benzene and cyclohexane by extractive distillation using deep eutectic solvent (DESs) as entrainer was proposed. Acetic acid (AA) was selected as hydrogen bond donor (HBD), tetraethylammonium bromide (TEAB) and tetraethylammonium chloride (TEAC) were selected as hydrogen bond acceptors (HBA), and two kinds of DESs were successfully prepared (i.e., DES1 is TEAC : AA = 1:3, DES2 is TEAB : AA = 1:3). Vapor liquid equilibrium experiments show that the relative volatility of benzene cyclohexane system can be significantly improved by using DESs as an entrainer, so that the separation of the target system can be achieved by extractive distillation. Further, quantitative calculations and molecular dynamics simulations were performed to explore the separation mechanism at the molecular level. The interaction sites between molecules were revealed by ESP analysis, and the interaction types between molecules were further elaborated by IGMH analysis. The results show that the Br atom of TEAB and the Cl atom of TEAC have hydrogen bonding with benzene, while there is π - π interaction between AA and benzene. The intermolecular interaction energy and spatial distribution function (SDF) further proved that the interaction between DES and benzene was stronger than that with cyclohexane. In conclusion, DES as entrainer for azeotrope separation has broad industrial application prospects.

The Role of Electrostatic Interactions in IFIT5-RNA Complexes Predicted by the UBDB+EPMM Method.

Electrostatic energy has a significant contribution to intermolecular interaction energy, especially in biological systems. Unfortunately, precise quantum mechanics calculations are not feasible for large biological systems; hence, simpler calculation methods are required. We propose a method called UBDB+EPMM (University at Buffalo Pseudoatom DataBank + Exact Potential Multipole Moments), which shortens computational time without losing accuracy. Here, we characterize electrostatic interactions in selected complexes of IFIT proteins with RNA. IFIT proteins are effectors of the innate immune system, and by binding foreign RNA, they prevent the synthesis of viral proteins in human host cells; hence, they block the propagation of viruses. We show that by using the UBDB+EPMM method it is possible to describe protein-RNA interactions not only qualitatively but also quantitatively. Looking at the charge penetration contribution to electrostatic interactions, we find all amino acid residues with strong local interactions. Moreover, we confirm that electrostatic interaction of IFIT5 with pppRNA does not depend on the sequence of the RNA.

Experimental and theoretical investigation into the response to shock wave for booster explosives JO9C, JH14, JH6, and insensitive RDX.

In order to reduce the vulnerability, the responses to shock waves for booster explosives JO9C, JH14, JH6, and insensitive RDX were evaluated using shock wave partition loading test. To explain the experimental results, molecular dynamics simulation, intermolecular interaction and bond dissociation energy (BDE), and shock initiation pressures were evaluated using the B3LYP, MP2 (full), and M06-2X methods with the 6-311 + + G(2df,2p) basis set. The order of the responsivity is JO9C > JH14 > JH6 > insensitive RDX. The binding energies follow the order of JH14* ≈ JO9C* < insensitive RDX* < JH6*. The interaction energies and BDEs are in RDX∙∙∙(CH3COOCa)+ > RDX∙∙∙CH3COOH > RDX∙∙∙CH2FCH2F. Thus, it can be inferred that for the RDX-based explosives, the stronger the binding energy, intermolecular interaction, and BDE are, the more insensitive the booster is, and thus, the larger energy has to be consumed to overcome the above three kinds of energies during the initiation process, leading to the smaller energy output and weaker response. However, it should be noted that it is mainly the density and the type of explosive that influence the depth of the dent produced on the steel witness block. The essence of the responses to shock waves is revealed by the reduced density gradient, atoms in molecules, and surface electrostatic potentials. HIGHLIGHTS: • Response of booster to shock wave was evaluated by shock wave partition loading test. • Responsivity to shock wave is explained by binding energy, intermolecular interaction, and BDE. • Shock initiation pressures were evaluated. • Essence of responses to shock wave is revealed by RDG, AIM and ESP.