Molecular Electrostatic Potential Analysis Research Articles

A pilot scale test study with theoretical justification of reaction mechanism for the recovery of chromium(VI) based on solvent extraction using novel centrifugal extractors

As a strategic resource and hazardous substance, the purification and recovery of chromium(VI) from the aqueous phase have attracted attention. In this study, the centrifugal extractor was used to treat the leach liquor of sodium roasting chromite on a pilot scale. The extraction performance and equilibrium distribution of chromium in countercurrent extraction were investigated. Meanwhile, the scrubbing effect of impurities was carefully studied, and the stripping and regeneration effects of the organic phase were tested. Under the selected process parameters, the pilot scale test results, including extraction efficiency of chromium, scrubbing efficiency of impurities, and regeneration performance of the organic phase, were excellent. The qualified (NH4)2Cr2O7 and Cr2O3 products were prepared using the strip liquor, and several physical properties of the products were tested. In addition, the molecular electrostatic potential surface maps, HOMO-LUMO orbitals, Fukui functions, and single point energy of the molecules involved were calculated by Quantum Chemistry. The molecular electrostatic potential analysis, frontiers molecular orbital analysis, Fukui function analysis and interaction energy analysis were applied to investigate the mechanism of separation of chromic acid from impurities in the extraction system.

Borophene as an carrier for mercaptopurine drug: electronic study via density-functional theory computations.

This paper studied MP-B36 interactions through DFT. MP molecules were observed to have a substantial tendency to be adsorbed through their N heads onto B36 at its edge, based on large adsorption energy values. The B atoms at the edges of B36 nanosheets showed higher reactivity than the internal B atoms toward MP. The electronic properties changed upon MP adsorption. The MP-B36 configurations of the highest stability underwent an energy gap reduction of 11-47%. Natural bond orbital (NBO) analysis and molecular electrostatic potential (MEP) analysis were used to evaluate the MP-B36 interaction. The configurations were subjected to geometric optimization at the TPSSH/6-31 + G(d) level of theory, at which frequency analysis was carried out to evaluate the stationary points. These configurations were neutral (Q = 0). The electronic properties of MP dramatically changed upon its interaction with B36 nanosheets. The stable configurations underwent an energy gap reduction, suggesting a chemical signal. The MP molecules were observed to be effectively adsorbed onto the B36 edge within aqueous phases. The MP-B36 configurations were estimated to have relatively large dipole moments. This demonstrated that MP-B36 systems were soluble and dispersed within solar media (e.g., water). It was concluded that B36 nanosheets could serve as efficient MP carriers in nanomedical drug delivery applications.

Theoretical investigations on structural, spectral, NBO, NLO and topology exploration (AIM, ELF, LOL, RDG) of piperazine-2,5-dione oxalic acid monohydrate

The present work investigates the structural stability and nonlinear optical (NLO) activity of piperazine-2,5‑dione oxalic acid monohydrate (PDOAH) using quantum chemical computational techniques. The optimized molecular structure and vibrational wavenumbers of the PDOAH molecule are determined by density functional theory (DFT) with B3LYP/6–311G(d,p) basis set. The vibrational wavenumbers, IR intensities, Raman activities and their corresponding PED values are obtained and analysed. Natural bond orbital (NBO) analysis is carried out to determine inter and intramolecular charge transfer interaction, intermolecular hydrogen bonding and hyperconjugative interactions that stabilize the structure. The charge transfer interaction, electrophilic, nucleophilic and chemical reactivity sites are identified with the aid of molecular electrostatic potential (MEP) and frontier molecular orbital (FMO) analysis. The TD-DFT method is utilized in UV–Vis spectral analysis for the molecule in the water solvent. RDG and IRI analysis is performed to spot the van der Waals interaction and steric effect within the molecule. The Hirshfeld surface analysis is carried out to scrutinize the intermolecular interactions. The nonlinear optical (NLO) parameters of PDOAH are evaluated through DFT calculation and compared with that of urea.

Investigational, computational explorations on betanin, lycopene, cyanidin, and peonidin organic photo sensitizers for green energy harvesting

In keeping green energy harvesting as a prime priority and lowering the cost per watt, three potential red-colored organic photosensitizers were separated and employed for proficient titanium dioxide (TiO2) photoanodes. In a prime attempt, Rivina Humilis fruit extract (Betanin) was used for natural dye-sensitized solar cells (NDSSCs). The Prunus cerasus fruits and Solanum lycopersicum fruits (Lycopene) extracts were also successfully employed to fabricate NDSSCs. Cyanidin, Peonidin, and Lycopene are the prominent colorants existent in Prunus cerasus, and their optimized molecular structure was premeditated via Density functional theory. Their thermochemistry and associated physical parameters, Frontier molecular orbitals (FMOs) analyses, theoretical ultraviolet (UV) – visible exploration, and molecular electrostatic potential reactivity analysis were studied. Microwave-assisted sol–gel practice has yielded pure anatase TiO2 nanoparticles (NPs). The pure, red dye-sensitized TiO2 NPs endured needed studies. Environment-friendly, cost-per-watt effective NDSSCs were accomplished by expanding three red-colored organic photoanodes. Among three photosensitizers, Rivina Humilis fruits showed 1.35%, followed by Prunus cerasus at 1.27 % and slightest by Solanum lycopersicum at 0.82%. And, owing to the above performances, these NDSSCs have the potential to be employed in low-power indoor energy harvesting.

Indapamide analogue a promising drug: Synthesis, a novel crystal structure, HSA/DFT/XRD, greener pastures biological study

A new indoline derivative, N-allyl-4-chloro-3-(N,N-diallylsulfamoyl)-N-(2-methylindolin-1-yl)benzamide (ASIB), indapamide analogue, has been synthesized via the N-allylation reaction and characterized by ESI-MS, IR, 1H & 13C NMR. The geometric parameters of the title compound, whose crystallographic structure has been defined by X-ray diffraction, have been calculated by Density Functional Theory (DFT), B3LYP, 6–311++G(d,p) basis set. For these operations, the data obtained by X-ray diffraction was used as initial values, and the calculated geometric parameters and experimental results were compared. In order to understand intermolecular interactions, Molecular Electrostatic Potential (MEP) and Hirshfeld Surface Analysis (HSA) studies were figured out for the molecule. Frontier Molecular Orbitals (FMO's) were created, and Energy Gap between Lowest Unoccupied Molecular Orbital (LUMO) and Highest Occupied Molecular Orbital (HOMO) was calcculated. Adapting Greener Pastures Biological Study (GPBS) aims to conduct a fair comparative study using accessible computer-aided software. ASIB, Indapamide, Asunaprevir, Danoprevir, and Vaniprevir were docked together using the same conditions and parameters to ensure a fair comparison. The binding scores against 6LU7 were −6.6, −7.1, −8.4, 7.6, and −7.9 kcal/mol−1 for ASIB, Indapamide, Asunaprevir, Danoprevir, and Vaniprevir, respectively. A relation between the molecule's binding score was due to the hydrophobic and hydrogen interactions between the ligand and the receptor's active amino acid residues. Worth pointing out here that the free energy and environmentally friendly in Silico molecular docking method aims mainly to rank ASIB, and Indapamide with respect to the approved drugs used in this study. Results support further investigation of ASIB as non-toxic a Diuretic, anti-COVID-19 and powerful antiviral drug as an indapamide derivative. Way2drug-PASS, Pro Tox-II and SwissADME are online software tools used in this study. Absorption, distribution, metabolism, excretion and toxicity (ADMET) properties of ASIB and its starting material (Indapamide) were compared.

Analyses on the reactivity, topology and bioactivity of Fluazinam using density functional theory

Quantum chemical computations were initiated to perform geometry optimization of Fluazinam by B3LYP/6–311 ++ G (d, p) basis set employing the DFT approach. Sample of Fluazinam dissolved in dichloromethane yielded single crystals for analysis through slow evaporation technique. For the objective of characterizing the title molecule, spectroscopic methods such as FT-IR, FT-Raman, NMR, and UV-Vis studies were used. The carbon atoms coupled to nitrogen atoms exhibit the strongest de-shielded signals, according to the NMR spectra. The observed UV-Vis spectrum is correlated with the computed spectrum. Natural Bond Orbital analysis interprets the charge delocalization within the molecule. Frontier molecular orbital (FMO), Molecular electrostatic potential (MEP) and Fukui function analyses were conducted to identify the chemical reactivity and hence the stability of the compound is evinced. Frontier molecular orbital study endorses a band gap of 3.66 eV which facilitates intra-molecular charge transfer. MEP study infers that the electronegative atoms behave as an electrophile while the hydrogen and carbon atoms take the nucleophilic reactivity. Weak covalent interactions as well as N-H…O intra-molecular hydrogen bonding were understood from the topology analyses. Molecular docking confirmed good binding affinity of -8.1 and – 7.6 Kcal/mol with the target proteins which were then ratified from the experimental activity assay showing a larger inhibition zone than the compared standard Nystatin.

Effect of resolution enhancement using metal ion assisted strategy based on electrospray ionization-ion mobility spectrometry: A case study of carbendazim and thiabendazole in fruits

A method for the rapid and simultaneous determination of carbendazim and thiabendazole residues by electrospray ionization-ion mobility spectrometry (ESI-IMS) combined with a metal ion-assisted technique was developed and validated in different fruit matrices. The metal ion assisted strategy was performed instead of tedious pre-separation procedures to overcome the limitation of low resolution of IMS. Four transition metal cations, Co(II), Ni(II), Cu(II), and Zn(II), were screened and their interactions with carbendazim and thiabendazole were investigated. The injection flow rate and metal ion concentration were optimized. The Cu(II) assisted approach helped to achieve well-separated peaks with a peak-to-peak resolution of 3.61. This method was then applied to detect carbendazim and thiabendazole simultaneously in apples, pears, bananas, and mangoes. The limit of detection (LOD) were 0.03 mg kg−1 and 0.13 mg kg−1 for carbendazim and thiabendazole, respectively, while spiked recoveries were 61.5–122.0% and 83.5–119.8%, respectively, with RSDs less than 13.9%. These satisfactory evaluation parameters indicated that the approach was capable of performing quantitative analysis of multi-pesticide residues. In addition, the feasibility of using metal ion assisted-ESI-IMS for the simultaneous detection also was theoretically demonstrated through molecular electrostatic potential analysis and binding energy calculation based on density functional theory (DFT). Both experimental and theoretical results revealed the effectiveness of the metal ion assisted strategy in improving the resolution of ESI-IMS.

Efficient removal of tetracycline by a novel bimetallic nickel/copper-loaded biochar: The crucial roles of π-π interaction and complexation

The development of a novel type of high-efficient biochar (BC) is important for the removal of tetracycline (TC). In this study, a bimetallic nickel/copper-loaded BC (Ni/Cu-BC) was synthesized, which had not been used for TC removal and lacked research on its safety and stability. The adsorption process was more likely to be monolayer chemical adsorption from the experiment. The density functional theory (DFT) calculation revealed that the interaction energy (Eads), energy gap (Eg) and dipole moment (P(D)) confirmed that the bimetallic loading improved the adsorption strength of the BC to TC. Moreover, the distribution of Ni/Cu-BC surface charge was considerably different from BC after bimetallic loading, and local polarization occurred according to the analysis of molecular surface electrostatic potential (ESP). It was demonstrated that the π-π interaction and complexation played a crucial role in the removal of TC. Finally, the functional groups of Ni/Cu-BC in removal were in the following order: CO > CC > NH2 > MO > CO. This study proves that Ni/Cu-BC is a novel, high-efficient, safe and reusable adsorbent. Overall, this study provides a new perspective on the design of BC and develops its environmental applications.

Engineering green MOF-based superhydrophobic sponge for efficiently synchronous removal of microplastics and pesticides from high-salinity water.

Microplastics (MPs) and pesticides are becoming an intractable environmental issue due to their wide spreading and non-degradable nature, posing serious threat to ecosystem and human health. To settle such dilemma, this work reasonably designed a superhydrophobic MOF-based coated sponge (ODSOSS/TiO2/Ni-MOF/PDA@Sponge) through the combination of an environmentally friendly in-situ supersaturated coprecipitation and polysesiloxane modification method. Among them, (I) the introduction of polydopamine (PDA) not only improves the adhesion between coatings and sponge, but also enhances the growth of MOF structure through complexation. (II) The obtained Ni-MOF shows large-area microscale anthemy structure with multilayered flaky texture, forming heterogeneously hierarchical structure with the deposited TiO2 nanoparticles, which promotes photodegradation ability of TiO2 owing to great specific surface area of Ni-MOF. (III) The high specific large area Ni-MOF supplies sufficient action sites for linkage of PDA and polysesiloxane molecules with unique nanocage-like structure, thus further greatly increasing adsorption force for various pollutants. (IV) The superhydrophobicity protect the porous channels of MOF from contamination of various absorbed pollutants, while TiO2 nanoparticles effectively photodegrade the absorbed organic pollutants, endowing the sponge superior recyclability. The superhydrophobic sponge selectively rapidly and synchronously adsorbs various MPs (maintained almost 100% after 60 cycles) and pesticides (adsorption rates 71.6%-95.1%) from high-salinity water. The large-area sponge (9cm×6cm×1cm) simultaneously removes almost 100% MPs (40mg/L), Sudan Ⅲ (10mg/L), kerosene (30mL/L), and four pesticides (10mg/L) within 1min. Particularly, four pesticides are quickly photocatalytic degraded by the coated sponge. The free radical capture trials show that hydroxyl radicals (·OH) are the main active species of pesticide degradation. Furthermore, we reveal the negative centers where pesticide molecules are most vulnerable to ·OH attack, on basis of the charge distribution and molecular electrostatic potential (MEP) analysis. The adsorption mechanisms are carefully clarified through theoretical calculation and experimental data. This work not only provide an effective superhydrophobic candidate for MPs and pesticides removal in a broad applicable scope (especially in high-salinity wastewater), but also opens a new strategy for environmental remediation.

Microwave assisted green synthesis, Single crystal XRD, DFT, Hirshfeld surface analysis, Antibiofilm, Anti-inflammatory activity and Molecular docking study of 4-(4-Fluorophenyl)-5-methyl-1,3-thiazole-2-amine

The title compound 4-(4-Fluorophenyl)-5-methyl-1,3-thiazole-2-amine was synthesized by the green microwave irradiation method and the structure was confirmed by spectroscopic techniques. Single crystal X-ray diffraction study was performed to investigate the crystal structure of the title compound. Further, the molecular structure was optimized by density functional theory (DFT) calculations using the B3LYP/6-311G++ (d, p) basic set and compared with X-ray diffraction data. DFT optimized structure, geometrical parameters and IR spectra of the title compound showed excellent correlations with the experimental results. The chemical reactivity and stability of the title compound were studied by molecular electrostatic potential (MEP) and Frontier molecular orbitals (FMOs) analysis. Intermolecular interactions of the title compound were analyzed by Hirschfeld surfaces and 2D-fingerprint plots. In vitro, antibiofilm activity against C. albicans, suggests a potential biofilm inhibitor (MIC 12.5 μg/ml). A molecular docking study of the title compound with the active sights of the target protein (PDB:5TZ1) justifies the results of the antibiofilm activity whereas a drug-likeness pharmacokinetic study is used to analyze the safety and efficiency of the drug. Furthermore, the Anti-inflammatory activity study of the title compound indicates significant (82.63%) inhibition of protein denaturation.

A DFT and QTAIM insight into ethylene oxide adsorption on the surfaces of pure and metal-decorated inorganic fullerene-like nanoclusters

In this industrial era, the use of low-dimensional nanomaterials as gas sensors for environmental monitoring has received enormous interest. To develop an effective sensing method for ethylene oxide (EO), DFT computations are conducted using method ωB97X-D and B3LYP with 6-31G(d,p) basis set to evaluate the adsorption behavior of ethylene oxide gas on the surfaces of pristine, as well as Scandium and Titanium decorated B12N12, Al12N12, and Al12P12 nanocages. Several properties like structural, physical, and electronic are studied methodically to better understand the sensing behavior. Scandium-decorated aluminum phosphate and boron nitride nanocages were shown to perform better in terms of adsorption properties. The short recovery time observed in this study is beneficial for the repetitive use of the gas sensor. The Natural Bond Orbital and molecular electrostatic potential analysis demonstrated a substantial quantity of charge transfer from adsorbate to adsorbents. The bandgap alternation after adsorption shows an influence of adsorption on electronic properties. The interactions of adsorbate and adsorbents are further studied using the ultraviolet–visible predicted spectrum, and quantum theory of atoms in molecules all of which yielded promising findings.

In vitro and in silico perspectives on the activation of antioxidant responsive element by citrus-derived flavonoids.

Oxidative stress plays an essential role in the pathogenesis of chronic diseases. Disrupting the Keap1-Nrf2 pathway by binding Keap1 is identified as a potential strategy to prevent oxidative stress-related chronic diseases. Therefore, of special interest is the utilization of dietary antioxidations from citrus, including narirutin, naringenin, hesperetin, hesperidin, naringin, neohesperidin dihydrochalcone, neohesperidin, and nobiletin, has been exploited as a prospective way to treat or prevent several human pathologies as Keap1-Nrf2 inhibitors for modulation of antioxidant properties. To probe into the structural foundation of the molecular identification of citrus-derived antioxidations, we calculated the antioxidant responsive element activation ability of citrus-derived flavonoids after binding with Keap1. Also, the quantum chemistry properties and binding mode were performed theoretically with frontier molecular orbitals, molecular electrostatic potential analysis, molecular docking, and absorption, distribution, metabolism, excretion (ADME) calculation. Experimental findings combining computational assays revealed that the tested citrus-derived flavonoids can be grouped into strong agonists and weak agonists. The citrus-derived antioxidations were well housed in the bound zone of Keap1 via stable hydrogen bonding and hydrophobic interaction. Eventually, three of eight antioxidations were identified after ADME and physicochemical evaluations. The citrus-derived flavonoids were identified as potential dietary antioxidants of the Keap1-Nrf2 interaction, and can be used to improve oxidative stress-related chronic diseases.

Hydrogen bond ferroelectric liquid crystal for tripartite temperature sensor: Experimental and computational (DFT) studies

The mesogenic behavior and electronic properties of hydrogen bond ferroelectric liquid crystal (HBFLC) complex are studied using experimental and theoretical techniques. HBFLC complex is synthesized from mesogenic 4-hexyloxy benzoic acid (6O BA) as the proton donor and nonmesogenic chiral DL-tartaric acid (DLTA) as the proton acceptor through intermolecular hydrogen bonding. Molecular geometry of DLTA+6O BA HBFLC complex is optimized by density functional theory (DFT) calculation. An interesting observation is that polarizing optical microscope (POM) study confirms that the HBFLC complex exhibits thermochromic behavior in chiral nematic (N[Formula: see text] along with induced nontitled smectic G* phases. Another noteworthy observation is the manifestation of tripartite temperature stages. Fourier-transform infrared spectroscopy (FTIR) and natural bond orbital (NBO) analysis elucidate the intermolecular hydrogen bond between mesogenic (6O BA) and nonmesogenic (DLTA) compounds. Further, frontier molecular orbital (FMO) study and electrostatic potential (ESP) analysis explore the reactivity sites, intermolecular charge transfer and electronic behavior of HBFLC complex.

A novel salt- and organic solvent-tolerant phosphite dehydrogenase from Cyanothece sp. ATCC 51142.

Phosphite dehydrogenase (PtxD) is a promising enzyme for NAD(P)H regeneration. To expand the usability of PtxD, we cloned, expressed, and analyzed PtxD from the marine cyanobacterium Cyanothece sp. ATCC 51142 (Ct-PtxD). Ct-PtxD exhibited maximum activity at pH 9.0°C and 50°C and high stability over a wide pH range of 6.0-10.0. Compared to previously reported PtxDs, Ct-PtxD showed increased resistance to salt ions such as Na+, K+, and NH4 +. It also exhibited high tolerance to organic solvents such as ethanol, dimethylformamide, and methanol when bound to its preferred cofactor, NAD+. Remarkably, these organic solvents enhanced the Ct-PtxD activity while inhibiting the PtxD activity of Ralstonia sp. 4506 (Rs-PtxD) at concentrations ranging from 10% to 30%. Molecular electrostatic potential analysis showed that the NAD+-binding site of Ct-PtxD was rich in positively charged residues, which may attract the negatively charged pyrophosphate group of NAD+ under high-salt conditions. Amino acid composition analysis revealed that Ct-PtxD contained fewer hydrophobic amino acids than other PtxD enzymes, which reduced the hydrophobicity and increased the hydration of protein surface under low water activity. We also demonstrated that the NADH regeneration system using Ct-PtxD is useful for the coupled chiral conversion of trimethylpyruvic acid into L-tert-leucine using leucine dehydrogenase under high ammonium conditions, which is less supported by the Rs-PtxD enzyme. These results imply that Ct-PtxD might be a potential candidate for NAD(P)H regeneration in industrial applications under the reaction conditions containing salt and organic solvent.

Shedding light into the biological activity of aminopterin, via molecular structural, docking, and molecular dynamics analyses

In this study, the structural and anticancer properties of aminopterin, as well as its antiviral characteristics, were elucidated. The preferred conformations of the title molecule were investigated with semiempirical AM1 method, and the obtained the lowest energy conformer was then optimized by using density functional (DFT/B3LYP) method with 6-311++G(d,p) as basis set. The vibrational frequencies of the optimized structure were calculated by the same level of theory and were compared with the experimental values. The vibrational assignments were performed based on the computed potential energy distribution (PED) of the vibrational modes. The molecular electrostatic potential (MEP) and frontier molecular orbitals (HOMO, LUMO) analyses were carried out for the optimized structure and the chemical reactivity has been scrutinized. To enlighten the biological activity of aminopterin as anticancer and anti-COVID-19 agents, aminopterin was docked into DNA, αIIBβ3 and α5β1integrins, human dihydrofolate reductase, main protease (Mpro) of SARS-CoV-2 and SARS-CoV-2/ACE2 complex receptor. The binding mechanisms of aminopterin with the receptors were clarified. The molecular docking results revealed the strong interaction of the aminopterin with DNA (−8.2 kcal/mol), αIIBβ3 and α5β1 integrins (−9.0 and −10.8 kcal/mol, respectively), human dihydrofolate reductase (−9.7 kcal/mol), Mpro of SARS-CoV-2 (−6.7 kcal/mol), and SARS-CoV-2/ACE2 complex receptor (−8.1 kcal/mol). Moreover, after molecular docking calculations, top-scoring ligand-receptor complexes of the aminopterin with SARS-CoV-2 enzymes (6M03 and 6M0J) were subjected to 50 ns all-atom MD simulations to investigate the ligand-receptor interactions in more detail, and to determine the binding free energies accurately. The predicted results indicate that the aminopterin may significantly inhibit SARS-CoV-2 infection. Thus, in this study, as both anticancer and anti-COVID-19 agents, the versatility of the biological activity of aminopterin was shown. Communicated by Ramaswamy H. Sarma

Synthesis of 1-Piperoylpiperidine Investigated Through Spectroscopy, Quantum Computation, Pharmaceutical Activity, Docking and MD Simulation Against Breast Cancer

1-Piperoylpiperidine (1-PIP) was crystallized as a single unit by a slow evaporation process, and it was examined using XRD and FT-IR spectroscopy. The centrosymmetric monoclinic structure is confirmed by XRD. The functional groups were determined by experimental FT-IR range from 4000 to 400 cm−1. Density functional theory was used to do calculations on quantum chemistry on B3LYP/6-311++G (d,p) theory. The vibrational wavenumbers were calculated, and experimentally obtained were assigned and compared. The molecule’s reactivity and kinetic stability are revealed via molecular orbital research. The Mulliken atomic charge distribution and molecular electrostatic potential analyses provide additional evidence of the molecule’s reactive site. The electronic spectrum was computed through TD-DFT and the electronic transition was attained at π→π*. The molecule’s bioactivity is shown by the natural bond orbital analysis. The efficiency and contribution of interactions between various atoms were evaluated using the Hirshfeld analysis. The DPPH assay was performed to access the antioxidant ability of 1-PIP. The disk diffusion test exhibited the antibacterial efficiency of 1-PIP molecule. The safety profile of 1-PIP was confirmed through physiochemical and pharmacokinetic predictions. In silico docking evaluation was performed for 1-PIP against 10 breast cancer-aided proteins and the higher binding affinity was recorded for NAMPT, which was further investigated through molecular dynamic (MD) simulation. MD simulation for a time period of 50 ns confirmed the stability of 1-PIP bounded NAMPT structure.

Novel Fluorinated Biphenyl Compounds Synthesized via Pd(0)-Catalyzed Reactions: Experimental and Computational Studies.

Five new difluorinated biphenyl compounds, 4'-(tert-butyl)-3,4-difluoro-1,1'-biphenyl (TBDFBP), 1-(3',4'-difluoro-[1,1'-biphenyl]-4-yl)ethanone (DFBPE), 3',4'-difluoro-2,5-dimethoxy-1,1'-biphenyl (DFDMBP), 3,4-difluoro-3'-nitro-1,1'-biphenyl (DFNBP), and (3',4'-difluoro-[1,1'-biphenyl]-3-yl)(methyl)sulfane (DFBPMS), have been successfully synthesized by the well-known Suzuki-Miyaura coupling with excellent yields averaging 78%. UV-visible, Fourier transform infrared ,and 13C NMR and 1H NMR spectroscopies along with single-crystal X-ray diffraction (SC-XRD) analysis (for TBDFBP and DFBPE) were used for the structure elucidation of the synthesized compounds. The SC-XRD results demonstrated the crystal systems of the studied compounds, TBDFBP and DFBPE, to be monoclinic, and their space groups were found to be P21/c. Also, a detailed density functional theory study was performed. The calculated structures for TBDFBP and DFBPE were found to agree quite well with the experimental results. The natural bonding orbital charge analysis suggested that molecules of these compounds should interact quite noticeably with each other in the solid phase and with polar solvent molecules. Molecular electrostatic potential analysis suggests that accumulation of positive and negative potential implies possibility of quite significant dipole-dipole intermolecular interactions in crystals of these compounds, as well as quite strong interactions with polar solvent molecules. The global reactivity parameters analysis suggests all compounds to be quite stable in redox reactions, with the compound DFNBP being relatively more reactive and the compounds TBDFBP and DFDMBP being relatively more stable.

Effect of functional group position in co-formers and solvent on cocrystal polymorphism/stoichiomorphism: a case study

In recent years, there has been an increase in the number of reports on cocrystal polymorphism and stoichiomorphism. However, the research on the factors that influence these phenomena is limited. Herein, picolinamide (PAM), nicotinamide (NAM), and isonicotinamide (INA) were selected as co-formers to form multicomponent solids with 4-chloro-3-sulfamoylbenzoic acid (CSBA). Six new cocrystal forms of CSBA were discovered and their crystal structures were determined. It was found that PAM and NAM can only form one cocrystal with CSBA, while INA can form up to four cocrystals, including both cocrystal polymorphism and stoichiomorphism. Molecular electrostatic potential analysis and crystal structure analysis showed that the functional group position of PAM limited the diversity of cocrystal synthons, while the lattice energy limited the diversity of cocrystal synthons when NAM acted as a co-former. Only INA was not subject to these restrictions when forming cocrystals. Finally, the influence of solvents on cocrystals was illustrated by determining the ternary phase diagrams. The mechanism of two similar solvents, ethyl acetate and acetone, controlling the crystallization of cocrystal polymorphism was analyzed by molecular simulations.

Molecular docking/dynamics simulations, MEP analysis, and pharmacokinetics prediction of some withangulatin A derivatives as allosteric glutaminase C inhibitors in breast cancer

The current study aims to understand the binding mechanism and intermolecular interactions of the novel Withangulatin A derivatives towards the allosteric site of Glutaminase C (GAC) using in silico analysis. The molecular docking and dynamics simulation results revealed that compounds L5, L8, L13, and L18 show high affinity toward the allosteric pocket of the GAC (PDB:3UO9), as confirmed by the high negative score values and hydrogen bonds. We found that these compounds interact with the most important residues and suggest a similar binding mechanism to the native compound (BPTES) and the clinical trial drug (CB-839). The combination of molecular electrostatic potential (MEP) analysis and molecular docking/dynamics studies confirms that the favorable reactive sites of these compounds establish many hydrogen bonds with active site residues of the target. Finally, pharmacokinetics prediction showed that L8 and L13 present the best ADMET profile among the selected compounds, and they share similar properties with the clinical compound CB-839. The obtained results in this investigation demonstrate that these two Withangulatin A derivatives might be used for further development as new allosteric GAC inhibitors for treating TNBC.

Theoretical insight of hydrochlorothiazide and aspirin adsorption on potassium and phosphorus doped carbon nanostructure as polypill prototype

Simultaneous adsorption of drugs on a novel carrier is a challenge for cardiovascular polypill design. The Density Functional Theory (DFT) calculations have been carried out to provide a possible mechanism associated with hydrochlorothiazide and aspirin adsorption on potassium- and phosphor- doped eighteen carbon nanostructure. The energetically most stable geometries are determined. The electronic structure of both molecules, as well as the doping nanostructure, before and after adsorption of the drugs, is studied. The molecular electrostatic potential analysis is presented and the orbital hybridizing is searched by the density of states plots. The results provide a direction for the further experiments in terms of through the recognition of binding trends and how the binding interaction change by modifying the surface.