Molecular Electrostatic Potential Surface Research Articles

Halogen Bond via an Electrophilic π-Hole on Halogen in Molecules: Does It Exist?

This study reveals a new non-covalent interaction called a π-hole halogen bond, which is directional and potentially non-linear compared to its sister analog (σ-hole halogen bond). A π-hole is shown here to be observed on the surface of halogen in halogenated molecules, which can be tempered to display the aptness to form a π-hole halogen bond with a series of electron density-rich sites (Lewis bases) hosted individually by 32 other partner molecules. The [MP2/aug-cc-pVTZ] level characteristics of the π-hole halogen bonds in 33 binary complexes obtained from the charge density approaches (quantum theory of intramolecular atoms, molecular electrostatic surface potential, independent gradient model (IGM-δginter)), intermolecular geometries and energies, and second-order hyperconjugative charge transfer analyses are discussed, which are similar to other non-covalent interactions. That a π-hole can be observed on halogen in halogenated molecules is substantiated by experimentally reported crystals documented in the Cambridge Crystal Structure Database. The importance of the π-hole halogen bond in the design and growth of chemical systems in synthetic chemistry, crystallography, and crystal engineering is yet to be fully explicated.

Insight into the solution thermodynamic properties of cimetidine form A and form B based on experiments and molecular simulations

Cimetidine (CIM) is an antagonist of the type II histamine receptors, and act as a significant agent in the treatment of stomach ulcers. In this work, the effect of polymorphism and solvent type on the thermodynamic properties of CIM was investigated based on experimental results and molecular simulations. The solubility data of two polymorphs for CIM (forms A and B) in organic solvents were measured and correlated with four thermodynamic models. It could be found that the solubility of CIM form A is higher compared to form B. In addition, molecular simulations were adopted to investigate the mechanism of the solubility and stability of the two forms. Hirshfeld surface analysis shows that strong H···N interaction contributes to better stability of form B. Meanwhile, molecular electrostatic potential surface and radial distribution function results indicate that the solubility behavior is significantly influenced by the intensity of the solute–solvent interactions. Finally, the dissolution thermodynamic properties, including the enthalpy change, the Gibbs energy change, and the entropy change, were calculated and the results show that the dissolution process of CIM is endothermic, entropy-driven and spontaneous.

Effect of TX-100 on solubilizing power of CTAB and CPC for H Acid: An experimental and computational analysis

The present research work investigates the solubility of an anionic dye 8-amino-1-naphthol-3,6-disulfonic acid (H Acid) within the micellar mediaof two cationic surfactants cetylpyridinium chloride (CPC) and cetyltrimethylammonium bromide (CTAB) as well as in the mixed micellar mediaof each cationic surfactant with Triton X-100 (TX-100). The data from differential absorption spectroscopy across a concentration range spanning from pre-micellar to post-micellar regions was used to determine the degree of solubilization by calculating the partition coefficient (Kx), binding constant (Kb) and Gibbs free energy associated with the relevant processes. Electrical conductivity of each cationic surfactant in the presence of H Acid was recorded in aqueous media and used to determine the CMC and subsequent thermodynamic parameters including entropy (ΔSm), enthalpy (ΔHm) and Gibbs free energy change (ΔGm) associated with the process of micellization. The computational analysis was carried out with GAUSSIAN 09 using a 6-311G + basis set with a DFT/ B3LYP hybrid approach and each set of energy minimization was executed to perform frequency calculations for Frontier molecular orbital analysis and to evaluate absorption spectra. Moreover, the molecular electrostatic potential surfaces (MESP) were also computed to find their suitable hydrophobic and hydrophilic interactions.

Synthesis, spectroscopic analysis (FT-IR, FT-Raman, UV, NMR), non-covalent interactions (RDG, IGM) and dynamic simulation on Bis(8‑hydroxy quinoline) salicylate salicylic acid

Using spectrum techniques and density functional theory (DFT) reckonings, structural, vibrational and electrical characteristics of Bis(8‑hydroxy quinoline) salicylate salicylic acid (8HQSA) were determined. Characterizing the chemical under inquiry involved employing FT-IR, FT-Raman, UV–vis spectral studies and single crystal X-ray diffraction (SCXRD). For the characterization, the B3LYP approach inside the structure of DFT was employed, with a 6–311++G(d,p) basis set. The structural study shows that the stability of 8HQSA crystalline structure arising from N–H⋯O, C–O⋯H and O–H⋯O hydrogen bonding interactions. The 1H and 13C NMR chemical shifts were calculated using Gauge Independent Atomic Orbital (GIAO) technical. Vibrational frequencies and molecular geometry were computed and likened with experimental data. Here, non-covalent interactions were deeply analyzed in terms of topological parameters (AIM), electron localization function (ELF), localized orbital locator (LOL), Hirshfeld surface and reduced density gradient (RDG) method. Weak interactions such as H-bonds, van der Waals and steric effect in 8HQSA were visualized and quantified by the independent gradient density (IGM) based on the trimolecular density. The hyper-conjugative and the delocalization of charge in 8HQSA have been elucidated by natural bonding orbital (NBO) while its chemical reactivity was studied and discussed by using molecular electrostatic potential surface (MEP), frontier molecular orbital (FMOs), density of state (DOS) and partial density of state (PDOS). The positions of the molecule's nucleophilic and electrophilic groups were ascertained using Fukui analysis. To describe the size, structure, and reactive sites of the molecules, the molecular electrostatic potential and total electron density are calculated. With a band gap (2.58 eV), FMO study indicates that the material is both bioactive and stable. The ADMET factor and drug similarity are used to predict 8HQSA's pharmokinetic characteristics. Based on the findings, it can be concluded that the 8HQSA particle is optimally crystallised and recommended as a preventative measure against bacterial and fungal infections. The stability of the title compound has been investigated via molecular dynamics simulations. In-vitro antimicrobial activity results clearly reveal that in all the four strains, activity increases with increase in compound concentration and the inhibition of the strains also increases. From both molecular docking and In-vitro Antimicrobial Activity the title compound can be certified that it inhibits antimicrobial activity.

Crystallographic and theoretical analysis of a spirohydantoin derivative: 3-(4‑tert-butylbenzoyl)-1,3-diazaspiro[4.5]decane-2,4‑dione

Providing structural information on drug-like compounds is a significant step in efforts to develop innovative drugs with balanced solubility, cell permeability and target binding. In this paper, a new cyclohexane-5-spirohydantoin tethered with a 4‑tert-butylbenzoyl group was synthesized and its crystal structure was determined using the single crystal X-ray diffraction. The Hirshfeld surface analysis was used to gain a preliminary insight into the proportion and nature of the intermolecular interactions in the crystal structure, while their quantitative description is further presented in terms of a systematic analysis of dimeric motifs representing different recognition modes. A combination of N–H∙∙∙O and C(sp3)–H∙∙∙O hydrogen bonds, C(sp3)–H∙∙∙π, lone-pair∙∙∙π and π∙∙∙π stacking interactions links the molecules into a bilayer having two carbonyl O atoms exposed to the exterior. Further stacking of the bilayers occurs through C(sp3)–H∙∙∙O hydrogen bonds involving these O atoms as acceptors, C(sp3)–H∙∙∙π and π∙∙∙π stacking interactions between the phenyl groups. The molecular electrostatic potential surface map reveals that the carbonyl O atoms of the hydantoin ring and the phenyl ring are electrophilic centers, while the N1–H1 group is a nucleophilic center. The calculated HOMO and LUMO energies were used to semiquantitatively estimate the global reactivity descriptors suggesting the soft nature of the molecule.

Synthesis, structural, multitargeted molecular docking analysis of anti-cancer, anti-tubercular, DNA interactions of benzotriazole based macrocyclic ligand

Biologically important macromolecule 1, 1′, 3, 3′ Bis − [2,3,5,6-Tetramethyl-p-phenylenebis(methylene)] dibenzotriazlinium dibromide hydrate (BTD) was synthesized and characterized using FT-IR, NMR and single-crystal XRD (SCXRD). SCXRD revealed that the compound was crystallized as a monoclinic system and associated through weak intermolecular interactions like H-bonding and π- π stacking interactions. These weak intermolecular interactions in BTD were studied using Crystal Explorer and Gaussian. The calculated energies for the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) showed the stability and reactivity of the title compound. Molecular electrostatic potential (MEP) surface analysis was used to investigate the crystal’s nucleophilic and electrophilic reactive sites. The molecular shape and intermolecular interactions in the crystal structure were determined using Hirshfeld surface analysis and fingerprint plots. Anticancer, anti-bacterial and DNA binding ability of BTD were investigated by experimental and theoretical techniques. The obtained results suggest that BTD possesses better anti-cancer, anti-bacterial and DNA binding abilities. The mode of action of antibiotic and anticancer approach was discussed. This provides promising therapeutic advantages for further development.

Experimental and simulation study on the solubility of 1-naphthylamine in twelve neat solvents

To meet the demand of separating and purifying 1-naphthylamine from the reaction production and filling the solubility data gap, the solubility of 1-naphthylamine in twelve pure solvents (acetone, acetonitrile, ethyl acetate, n-butyl acetate, cyclohexane, n-heptane, methanol, ethanol, n-propanol, iso-propanol, n-butanol, and iso-butanol) was experimentally investigated in the range from 273.15 K to 308.15 K. It was found that the solubility of 1-naphthylamine increases markedly with increasing temperature in all solvent systems. The maximum solubility was 0.8978 (in the solvent of acetone,T = 308.15 K) and the minimum solubility was 0.005485 (in the solvent of n-heptane, T = 273.15 K). Then the experimental solubility data was correlated by the modified Apelblat model, Van't Hoff model, NRTL model, Wilson model, and Margules model. ARD% was calculated to assess the accuracy of the five equations and the results indicated that the modified Apelblat model fits optimally with an average ARD% value of 1.62 %. The effects of various physicochemical properties such as solvent polarity, hydrogen bond donor, hydrogen bond acceptor, and cohesive energy density on solute dissolution behavior were explored. In addition, the apparent thermodynamic properties of 1-naphthylamine in different solvents were analyzed based on modified Van’t Hoff model, which indicated the dissolution process of 1-naphthylamine in selected solvents is endothermic and entropy-driving. Finally, the effect of intermolecular interactions on the dissolution behavior was investigated at the molecular scale through molecular dynamics simulation studies, including molecular electrostatic potential surface, solvation free energy and radial distribution function analysis. This work will provide a fundamental guidance for the crystallization, separation, and purification of 1-naphthylamine.

Synthesis, NMR, electronic properties using DFT study and anticancer activity of 3-methyl-6-(m-tolylamine) quinazolin-4(3H)-one

3-methyl-6-(m-tolylamine) quinazolin-4(3H)-one (MTAQ) was synthesized. Its formation was ascertained with the help ESI mass spectroscopy in conjunction with 1HNMR spectroscopy. Anticancer activity of MTAQ was measured experimentally, for human carcinoma cell line pertaining to cervix (HeLa). Optimized structure parameters, Frontier molecular orbital (FMO) behavior, non linear optical (NLO) profile, molecular electrostatic potential surface (MESP), Fukui functions (FF) and thermodynamic parameters were evaluated for the molecule of interest employing DFT/B3LYP/6–311++G(d,p) formalism. TD-DFT was made use of to calculate absorption maxima (λmax) of electronic transitions for the molecule in CDCl3 solvent. Frontier molecular orbitals revealed the origin of UV–Vis spectrum and to comprehend chemical reactivity of the molecule. Good coincidence was noticed between measured and computed structure parameters, UV–Vis spectra, and 1HNMR signals. Fukui functions helped in identifying electrophilic and nucleophilic centers of MTAQ. The calculations showed that MTAQ exhibits significant NLO activity in addition to predicting existence of intramolecular hydrogen bond.

Fascinating inclusion of metal–organic complex moieties in dinuclear Mn(II) and Zn(II) compounds involving pyridinedicarboxylates and phenanthroline: Experimental and theoretical studies

In the present study, we have reported the synthesis of two new dinuclear Mn(II) and Zn(II) metal–organic compounds, [Mn(2,5-PDC)(phen)2][Mn(phen)2(H2O)2]2Cl·10H2O (1) and [Zn(phen)3][Zn(2,6-PDC)2]·11.5H2O (2) (where, 2,5-PDC = 2,5-pyridinedicarboxylate, 2,6-PDC = 2,6-pyridinedicarboxylate, phen = 1,10-phenanthroline) at room temperature which have been characterized by elemental analysis, TGA, spectroscopic (FTIR, electronic) and single crystal X-ray diffraction techniques. A fascinating chloride-water supramolecular cluster in 1 and (H2O)13 H-bonded cluster in 2 along with π-stacked assemblies stabilize the solid state structures. The most interesting aspect of the crystal structure of 1 is the inclusion of complex cationic moieties within the infinite self-assembled chloride-water cluster. Similarly the inclusion of cationic complex moieties in compound 2 inside the supramolecular cavity formed by the anionic complex provides rigidity to the crystal structure. DFT calculations, molecular electrostatic potential (MEP) surface analysis, quantum theory of atoms-in-molecules (QTAIM) and the non-covalent index plot (NCI plot) analysis were performed to investigate the supramolecular assemblies of the compounds. The studies reveal that the antiparallel π-stacking interactions are energetically significant synthons for the assemblies. However, the assemblies in 2 have been dominated mostly by Columbic attraction of the cationic and anionic complex moieties.

Photochemical properties and toxicity of fluoroquinolone antibiotics impacted by complexation with metal ions in different pH solutions

Acid-base dissociable antibiotic-metal complexes are known to be emerging contaminants in the aquatic environments. However, little information is available on the photochemical properties and toxicity of these complex forms. This study investigated the spectral properties of three fluoroquinolones (FQs) with and without metal ions Fe(III), Cu(II), and Al(III) in solutions under different pH conditions, as well as evaluated the changes in toxicity due to the complex with these metal ions using luminescent bacteria (vibrio fischeri). FQs showed a higher tendency to coordinate metal ions under alkaline conditions compared to neutral and acidic conditions, and the formation of complexes weakened the ultraviolet-absorbing ability of FQs. At pH = 7.0, Cu(II) quenched the fluorescence intensity of FQs. Moreover, their Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy were explored, revealing that the coordination sites of Cu(II) in three FQs were situated in a bidentate manner through the oxygen atom of the deprotonated carboxyl group and cyclic carbonyl oxygen atom. This conclusion was further verified by the theory of molecular surface electrostatic potential. In addition, except for complexes of ciprofloxacin-metals, enhanced toxicity of FQs upon coordination with Fe(III) was observed, while reduced toxicity was found for coordination with Cu(II) and Al(III). These results are important for accurately evaluating the photochemical behavior and risk of these antibiotics in aquatic environments contaminated with metal ions.

Depicted simulation model for removal of second-generation antipsychotic drugs adsorbed on Zn-MOF: adsorption locator assessment.

Electronic durable behavior on the material surface was accompanied by a class of antipsychotic drugs (APD) to describe the surface modification in the designed adsorption model. Hierarchically Zn-MOF system was utilized for estimating its capacity for drug molecule removal. Geometrically optimized strategy on the studied systems was performed using DFT/GGA/PBE. FMOs analysis was depicted based on the same level of calculations, and molecular electrostatic potential surface (MEP) was generated for unadsorbed and adsorbed systems to illustrate the variation in the surface-active sites. By interpreting the electronic density of states (DOS), the atomic orbital can be identified as a major or minor electronic distribution by PDOS graph. Adsorption locating behavior was considered to detect the significant surface interaction mode between APD and Zn-MOF surface based on lower adsorption energy. The stability of the adsorbed model was best described through dynamic simulation analysis with time through elevated temperatures. The non-covalent interactions were described using RDG/NCI analysis to show the major favorable surface interaction predicting the highly stable adsorption system. The most accurate geometrical computations were performed using the materials studio software followed by surface cleavage and vacuum slab generation. The first principle of DFT was used to apply CASTEP module with GGA/PBE method for band structure and DOS calculations. Three systems of antipsychotic drugs were computationally studied using CASTEP simulation package and adsorbed on an optimized Zn-MOF surface. Adsorption locator module predicted the preferred adsorption mechanistic models, in which the first model was arranged to be more stable, to confirm the occurrence of some interactions in the adsorption mechanism.

SERS analysis, DFT, and solution effects regarding the structural and optical characteristics of folic acid biomolecule adsorbed on a Cu3 metal cluster

The optical characteristics of folic acid (ABP) and metal clusters of copper (Cu3) at various locations were investigated by means of density functional theory (DFT) computations. Mulliken charge analysis and molecular electrostatic potential (MEP) surface show how charge moves from Cu3 to ABP through the various groups. The peak in the UV–Vis spectra of ABP-Cu3 is caused by bonding and anti-bonding orbitals. In both vacuum and aqueous conditions, the polarizability values of ABP-Cu3 cluster are significantly higher than those of pure ABP, indicating a possible enhancement of the nonlinear optical (NLO) effect. Our research investigates the possibility of using ABP adsorbed metal clusters for NLO materials. Surface enhanced Raman scattering (SERS) in the ABP adsorbed metal clusters enhances the vibrational modes of ABP. Adsorption energies are found to be in the range −17.08 to −58.52 kcal/mol in vacuum and −53.34 to −93.44 kcal/mol in aqueous medium for the different configurations for ABP-Cu3. It indicates that metal clusters adsorbed by ABP are stable in the aqueous media. Experimental IR and UV–Vis of ABP is in agreement with theoretically predicted ones.

Synthesis, crystal structure, DFT calculation, Hirshfeld suface analysis and antitumor activity of 4-(tert-butyl)-5-(1H-1,2,4-triazole-1-yl)thiazole derivatives containing benzoxazinone

Seven novel 4-(tert-butyl)-5-(1H-1,2,4-triazole-1-yl)thiazole derivatives containing benzoxazinone (B1-B7) were obtained by cyclization of 4-(tert-butyl)-5-(1H-1,2,4-triazol-1-yl)-N-(2-hydroxy-benzyl)thiazol-2-amine. The chemical structures of the target compounds were confirmed by 1H NMR and 13C NMR. The single crystal X-ray diffraction revealed that B1 crystallizes in a triclinic system with the space group P1¯. Hirshfeld surfaces and two dimensional (2D) fingerprint plots were employed to quantitatively characterize the influence of intermolecular interactions within the crystal lattice of B1. And the molecular electrostatic potential (MEP) surface was calculated employing Becke-3-Lee Yang Parr (B3LYP)/6-311++G (d,p) theoretical approach. Meanwhile, the Frontier-molecular orbitals of B1 and B2 were calculated using density functional theory (DFT) B3LYP technique with the def2-SVP basis set in the ground state. Preliminary biological tests revealed that the title compounds had certain antitumor activities against three cell lines MCF-7, Hela and A549, and compound B2 presented the most potent antitumor efficacy against A549.

Exploring the non-covalent interactions, vibrational and electronic properties of 2-methyl-4-hydro-1,3,4-triazol-thione-5 in different solutions

In this study, the optimal geometry and vibrational assignments of 2-methyl-4-hydro-1,3,4-triazol-thione-5, one of the triazole derivatives, were analysed by the DFT approach and vibrational spectroscopy. PED values were calculated, and vibrational assignments were determined. Experimental results showed that interactions between 2-methyl-4-hydro-1,3,4-triazol-thione-5 and solvent (acetone, acetonitrile, dioxane, and DMF) molecules lead to a red shift of the N-H stretching vibrational band. The computations were performed at the B3LYP/6-311++G(d,p) functional set. The molecular electrostatic potential surface was used to distinguish between electrophilic and nucleophilic regions. The reactivity of the molecular complexes was determined by examining their frontier molecular orbitals. Topological investigations revealed the existence of N-H…N and N-H…O-type hydrogen bonds between 2-methyl-4-hydro-1,3,4-triazole-thiol-5 and solvent molecules. The red-shift of the N-H stretching band and H-bond strength between solute–solvent molecules are in the order of acetonitrile, acetone, dioxane, and DMF.

Bistriazolotriazole-tetramine: commendable energetic moiety and cation.

Various 7H,7'H-[6,6'-bi[1,2,4]triazolo[4,3-b][1,2,4]triazole]-3,3',7,7'-tetramine (A) based nitrogen-rich energetic salts were designed and their properties explored. All energetic salts possess relatively high nitrogen content (> 48%), positive heats of formation (> 429kJ/mol) and stability owing to a significant contribution from fused backbone. The cationic component shows a very high heat of formation (2516kJ/mol); therefore, it is highly suitable for enthalpy enhancement in new energetic salts. The cation was paired with the energetic anions nitrate (NO3-), perchlorate (ClO4-), dinitromethanide (CH(NO2)2-), trinitromethanide (C(NO2)3-), nitroamide (NHNO2-), and dinitroamide (N(NO2)2-) to improve oxygen balance and detonation performance. Designed salts show moderate detonation velocities (7.9-8.7 km/s) and pressures (23.8 - 33.1 GPa). The distribution of frontier molecular orbitals, molecular electrostatic surface potentials, QTAIM topological properties, and noncovalent interactions of designed salts were simulated to understand the electronic structures, charge distribution in molecules, hydrogen bonding, and other nonbond interactions. The predicted safety factor (SF) and impact sensitivity (H50) of designed salts suggest their insensitivity to mechanical stimuli. This work explored the 7H,7'H-[6,6'-bi[1,2,4]triazolo[4,3-b][1,2,4]triazole]-3,3',7,7'-tetramine as a suitable cationic component which could be promising and serve exemplarily in energetic materials. The optimization and energy calculations of all the designed compounds were carried out at the B3LYP/6-311 +  + G(d,p) and M06-2X/def2-TZVPP levels, utilizing the Gaussian software package. The molecular surface electrostatic potential, quantum theory of atoms in molecules (QTAIM), reduced density gradient (RDG), and noncovalent interaction (NCI) analysis were performed by employing Multiwfn software. The EXPLO5 (v 7.01) thermochemical code and PILEM web application were used to predict the detonation properties.

DFT and molecular simulation validation of the binding activity of PDEδ inhibitors for repression of oncogenic k-Ras.

The development of effective drugs targeting the K-Ras oncogene product is a significant focus in anticancer drug development. Despite the lack of successful Ras signaling inhibitors, recent research has identified PDEδ, a KRAS transporter, as a potential target for inhibiting the oncogenic KRAS signaling pathway. This study aims to investigate the interactions between eight K-Ras inhibitors (deltarazine, deltaflexin 1 and 2, and its analogues) and PDEδ to understand their binding modes. The research will utilize computational techniques such as density functional theory (DFT) and molecular electrostatic surface potential (MESP), molecular docking, binding site analyses, molecular dynamic (MD) simulations, electronic structure computations, and predictions of the binding free energy. Molecular dynamic simulations (MD) will be used to predict the binding conformations and pharmacophoric features in the active site of PDEδ for the examined structures. The binding free energies determined using the MMPB(GB)SA method will be compared with the observed potency values of the tested compounds. This computational approach aims to enhance understanding of the PDEδ selective mechanism, which could contribute to the development of novel selective inhibitors for K-Ras signaling.

Growth, DFT, spectroscopic analysis, third-order NLO properties and optical limiting behavior of Bis(p-aminobenzoic acid-N) dichloro cadmium (II) (BPANDC) crystal

A new organic nonlinear optical crystal, Bis(p-aminobenzoic acid-N) dichloro cadmium (II) (BPANDC) has been grown by Slow Evaporation Solution Technique (SEST). The experiments were carried out to study the structural, optical, DFT and nonlinear optical properties of the grown crystals. The BPANDC crystal belongs to triclinic system with space group Pī with lattice parameters a = 6.359(4)Å, b = 7.509(11)Å, c = 17.263(7)Å, α= 94.50(2)˚, β=104.56(2)˚, γ=96.79(4)˚, and volume V = 787.20Å3. Using the TD-DFT method, the electronic absorption spectra of BPANDC was calculated in gas phase. The calculated FT-IR, FT-Raman spectrum, Molecular geometrical analysis, TD-DFT, HOMO–LUMO energy gap and Molecular electrostatic potential surface of BPANDC were calculated by DFT/ LANL2DZ basis set. The Z-scan analysis evidenced that the BPANDC exhibits sequential two-photon absorption induced reverse saturable absorption.

Experimental and molecular simulation analysis of the dissolution behavior of Musk ambrette in organic solvents

The solubility of Musk ambrette in i-propanol (IPA), i-butanol (IBA), n-heptane (HPT), n-hexane (HX), cyclohexane (CYH), methyl acetate (MAC), ethyl acetate (EAC), acetone (ACE), IPA + ACE at 278.15 K to 318.15 K was determined. The mole fraction solubility of Musk ambrette in pure IPA at the temperature of 298.15 K were found to be 0.9492 × 10-2 mol·mol−1. The difference is that the solubility of Musk ambrette in ACE reaches 0.2257 mol·mol−1, which is much higher than the solvent mentioned above. The strong intermolecular hydrogen bonding formed by IPA resulted in its lowest solvation capacity for Musk ambrette. In addition, to further investigate the solubility pattern of Musk ambrette, we used 8 models (Van’t Hoff, modified Apelblat, Buchowski-Ksiazczak, Yaws, NRTL, Wilson, Jouyban-Acree and Sun model) to fit and obtain a general equation for solubility versus temperature. These results yielded a large amount of statistically significant data. Comparisons revealed that the modified Apelblat and Yaws equation showed the least deviation in forecasting solubility variations with temperature. Meanwhile, we proved that the dissolution of Musk ambrette is a heat-absorbing entropy increasing process by Van't Hoff equation calculation. ΔsolGo for the 12 solvents is in the following order: ACE < MAC < EAC < w = 0.2007 < w = 0.4025 < w = 0.6076 < CYH < w = 0.8070 < HPT < HX < IBA < IPA. ΔsolGo is smaller the easier it dissolves, which is consistent with the law of dissolution. Secondly, we performed thermal analysis and X-ray diffraction tests on Musk ambrette crystals prepared in different solvents, which showed that none of the several systems investigated led to the creation of new crystalline forms or solvatoids, further confirming the suitability of the solvents. Besides, we discuss the correspondence between solubility and the HSP, π, α, β, and CED of the solvents and thus tentatively confirm the significant influence of the solvent properties on solubility. The principle of similarity and compatibility is satisfied for most of the solvents. In particular, the CED values of the larger solvents were not favorable for the solubilization of Musk ambrette. We also analyzed the molecular surface electrostatic potential of Musk ambrette by visualization techniques. Finally, IPA and ACE and their binary solution systems were analyzed by molecular dynamics simulations. The effect of solvent intermolecular interactions on the solubilization pattern was discussed. It was further confirmed that weak interactions of solvent molecules contribute more to the dissolution of Musk ambrette. These findings suggest that the prediction of solvent solubility can be initially achieved by molecular simulation techniques. Undoubtedly, this study will furnish a valuable information for the purification of Musk ambrette.

Synthesis, in vitro α‐Glucosidase Inhibition, DFT Calculations, and Molecular Docking Studies of Some New Substituted 2,5‐Bis(pyrazolyl)‐1,3,4‐oxadiazoles

AbstractA pivotal feature of present research study is the synthesis of some new 2,5‐bis(pyrazolyl)‐1,3,4‐oxadiazoles as promising α‐glucosidase inhibitors. In this regard, a facile reaction scheme was designed to afford 1,3,4‐oxadiazole ring. In search of the most favourable reaction condition, a model reaction was first carried out between 1,3‐diphenyl‐1H‐pyrazole‐4‐carbohydrazide (3) and 1,3‐diphenyl‐1H‐pyrazole‐4‐carboxylic acid (4 a) using phosphorous oxychloride (POCl3). The results emanated from this model reaction were utilized to prepare other derivatives to highlight the scope of current synthetic approach and the structures of the prepared molecules were characterized from spectroscopic techniques. These derivatives were further investigated for their α‐glucosidase inhibitory potentials. 2,5‐Bis(1,3‐diphenyl‐1H‐pyrazol‐4‐yl)‐1,3,4‐oxadiazole (5 a) and 2‐(3‐(4‐bromophenyl)‐1‐phenyl‐1H‐pyrazol‐4‐yl)‐5‐(1,3‐diphenyl‐1H‐pyrazol‐4‐yl)‐1,3,4‐oxadiazole (5 c) displayed strong in vitro inhibitory activities with IC50 73.1±1.13 μM and IC50 87.3±1.12 μM respectively with least toxicity profiles. Molecular docking and computational studies including geometry optimization of synthesized molecular systems, calculations of their orbital energies, and molecular electrostatic potential (MEP) surface maps further helped to establish structural and electronic properties contributing towards their bioactivity. The electrophilicity index significantly quantifies the biological activity. The experimental and computational data altogether facilitated in understanding the therapeutic attributes of these versatile scaffolds in relation to their α‐glucosidase inhibition.

Coordination nanosheets based molecular computing for detection and differentiation of high-energy explosives TATB and FOX-7

Detection and differentiation of explosives is an issue of immediacy for security and environmental monitoring. At present, the most operated explosive system combines primary and secondary explosives. Although various advances are presently equipped for identifying primary explosives, the insensitive nature of secondary explosives makes their detection and differentiation challenging. Here, we report three coordination nanosheets (CNs) AM-8-Eu, AM-8-Tb, and AM-8-Zn containing three-way terpyridine ligands (AM-8) and Eu(III), Tb(III), and Zn(II) ions. These CNs act as a highly selective platform for detecting unexplored high-energy explosive 1,1-Diamino-2,2-dinitro ethylene (FOX-7) in solid and solution phases. For AM-8-Zn, calculated molecular electrostatic surface potential revealed two modes of interactions for triaminotrinitrobenzene (TATB) and FOX-7, producing two distinct spectral responses. Digital analysis of these responses revealed a complimentary implication (IMP)/not implication (NIMP) logic function. Finally, the unique feature of IMP gate is used to define all possible sixteen distinct binary Boolean operations on two logic values for “functional completeness”. The detection and differentiation of such insensitive high-energy explosives TATB and FOX-7, where Boolean logic can process information through distinct binary responses in solid and solution phases, have not been witnessed hitherto in a single chemical platform.