Negative Electrostatic Potential Research Articles

Identification of new triazolo annulated dipyridodiazepine derivatives as HIV-1 reverse transcriptase inhibitors: Design, synthesis, DFT, molecular modelling and in silico studies

With the tremendous increase in viral infection spread and drug resistance, it is imperative to explore new efficient antiviral agents. Two series of novel compounds, triazole-annulated dipyridodiazepines 9(a–e) and methyl-substituted triazole-annulated dipyridodiazepines 10(a–e), were successfully synthesised and characterised by IR, NMR spectroscopy and mass spectrometry. The in vitro reverse transcriptase inhibitory ability of synthesized derivatives was determined using an HIV-1 reverse transcriptase assay kit. Results revealed that 9a and 10a were most potent with an IC50 of 66 and 71 nM compared with reference drug nevirapine 88nM. A density functional theory (DFT) study of the synthesized compound showed that both triazole series possess noticeably distorted butterfly-like structures, triazole and pyridine rings tilted relative to the diazepine ring and the phenyl ring is perpendicular to the diazepine ring. Significant HOMO/LUMO gap values for both series, 3.71–4.59 eV for the compounds 9(a–e) and 3.69–4.68 eV for compounds 10(a–e), suggest their quite noticeable stability. Further, these analogues were in silico analysed for molecular docking, drug-likeness, physicochemical and ADMET studies. The good binding scores (high interaction energies) obtained in the molecular docking studies are in good agreement with the molecular electrostatic potential (MEP) analysis results showing accumulations of negative and positive electrostatic potential on different parts of the molecules of the compounds studied. In conclusion, all these results suggest that synthesized analogues could be a potential candidate to inhibit HIV-1 reverse transcriptase and may be considered as lead molecules in the development of new anti-reverse transcriptase agents.

Study on the compounding optimization of surfactants and synergistic effects on the wettability of bituminous coal

To improve the wettability of surfactants on bituminous coal and to explore its wettability and wettability mechanism on bituminous coal, taking the Sandaogou bituminous coal as an example, a single factor experiment was carried out first. Through contact angle and surface tension experiments, three surfactants with good wettability were selected from among the nine surfactants and mixed in equal proportions two by two to determine the optimal compounding method and compounding concentration. The experimental results show that the compounding of nonionic and anionic, nonionic and zwitterionic, anionic and zwitterionic surfactants can have synergistic effects and significantly improve the wettability of bituminous coal. Among them, the 0.5 wt% SDS + 0.5 wt% CAB-50 (R2) compound surfactant had the best wettability on bituminous coal, and the contact angle and surface tension were only 15.24° and 23.62 mN/m, respectively. The surface electrostatic potential values of each material molecule were calculated by Materials Studio software based on the quantum chemistry method, and correlation analysis was carried out with wettability. The results show that the surface electrostatic potentials of CDEA, SDS and CAB-50 were greater than those of water and bituminous coal, and the region of maximum negative electrostatic potential corresponded to oxygen atoms, which are easier to adsorb on bituminous coal and water molecules. Then, through molecular dynamics simulation, the interaction energy and the distribution of contributions along the Z-axis of the water/compound surfactant/bituminous coal system at equilibrium were investigated, and finally, a spray dust reduction test was carried out in the Sandaogou Coal Mine. The results showed that the 0.5 wt% SDS + 0.5 wt% CAB-50 compound solution can be used as a water molecule adsorption carrier, prompting more water molecules to be embedded into coal molecules, increasing the relative concentration of water molecules on the surface of bituminous coal, restricting the diffusion of water molecules, and greatly improving the wettability. After the addition of 0.5 wt% SDS + 0.5 wt% CAB-50 as a spray agent, the concentration of total dust at the driver's position decreased from 65.14 to 9.11 mg/m3, the concentration of exhaled dust decreased from 30.07 to 3.35 mg/m3, and the efficiency of total and exhaled dust reduction compared with that of pure water was 86.01% and 89.35%, respectively.

Research on triamterene equilibrium solubility in mono-solvents and aqueous solutions according to solvent effect, models, thermodynamic analysis and quantum chemical calculation

The equilibrium solubilities of triamterene in pure solvents {isopropanol, methanol, n-propanol, water, 1,2-dichloroethane, 2-methoxyethanol, ethyl acetate, acetonitrile, N-methylformamide (NMF), n-butanol, isobutanol and dimethylsulfoxide (DMSO)}, as well as solvent mixtures of methanol/DMSO + water, were determined by dint of the saturation shake-flask technique. Triamterene solubility (105x) rose as the determination temperature rose and fell in the order at 298.15 K: 2-methoxyethanol (453.9) > DMSO (281.3) > NMF (142.6) > methanol (8.424) > n-propanol (1.432) > n-butanol (1.152) > ethyl acetate (0.9441) > isobutanol (0.8738) > acetonitrile (0.7991) > isopropanol (0.7419) > 1,2-dichloroethane (0.5232) > water (0.1795). No crystal transition or solvation in the trial process was shown via X -ray power diffraction patterns. The solvent effects, in which the interactions of solvent–solvent and solvent–solute were considered, were studied via linear solvation energy relationship. Using equations such as Wilson, Apelblat, λh, and NRTL for mono-solvents and Jouyban-Acree as well as modified van't Hoff-Jouyban-Acree for solvent mixtures, the magnitudes of equilibrium solubility were associated. The greatest relative average deviation of 5.787 × 10−2 and the maximum deviation value of root mean square of 219.1 × 10−4 were computed for neat solvents. According to the solubility information in pure solvents, the Wilson equation was used to compute the mixing solution parameters. At 298.15 K, the inverse Kirkwood-Buff integral was utilized here to examine the preferred solvation of triamterene. In blends of DMSO/methanol + water with middle and rich DMSO/methanol compositions, the parameters of preferred solvation for DMSO/methanol were positive, indicating the preferential solvation of triamterene by DMSO/methanol. In addition, the electrostatic acidity-basicity properties were demonstrated using the lowest negative electrostatic potential in company with the minimum m local ionization energy of molecular surface. The N in ring of the triamterene is the preferential target for electrophilic assault; and –NH2 of the triamterene, for nucleophilic assault. The weak triamterene-solvent interactions were graphically displayed by the use of the independent gradient approach on the basis of Hirshfeld partition analysis.

Animal-derived food allergen: A review on the available crystal structure and new insights into structural epitope.

Immunoglobulin E (IgE)-mediated food allergy is a rapidly growing public health problem. The interaction between allergens and IgE is at the core of the allergic response. One of the best ways to understand this interaction is through structural characterization. This review focuses on animal-derived food allergens, overviews allergen structures determined by X-ray crystallography, presents an update on IgE conformational epitopes, and explores the structural features of these epitopes. The structural determinants of allergenicity and cross-reactivity are also discussed. Animal-derived food allergens are classified into limited protein families according to structural features, with the calcium-binding protein and actin-binding protein families dominating. Progress in epitope characterization has provided useful information on the structural properties of the IgE recognition region. The data reveals that epitopes are located in relatively protruding areas with negative surface electrostatic potential. Ligand binding and disulfide bonds are two intrinsic characteristics that influence protein structure and impact allergenicity. Shared structures, local motifs, and shared epitopes are factors that lead to cross-reactivity. The structural properties of epitope regions and structural determinants of allergenicity and cross-reactivity may provide directions for the prevention, diagnosis, and treatment of food allergies. Experimentally determined structure, especially that of antigen-antibody complexes, remains limited, and the identification of epitopes continues to be a bottleneck in the study of animal-derived food allergens. A combination of traditional immunological techniques and emerging bioinformatics technology will revolutionize how protein interactions are characterized.

DFT and TDDFT exploration on electronic transitions and bonding aspect of DPA and PTDC ligated transition metal complexes.

In this study, we have investigated the structure, reactivity, bonding, and electronic transitions ofDPAandPDTC along with theirNi-Zncomplexes usingDFT/TD-DFT methods. The energy gap between the frontier orbitals was computed to understand the reactivity pattern of the ligands and metal complexes. From the energies of FMO's, the global reactivity descriptors such as electron affinity, ionization potential, hardness (η), softness (S), chemical potential (μ), electronegativity (χ), and electrophilicity index (ω) have been calculated. The complexes show a strong NLO properties due to easily polarization as indicated by the narrow HOMO-LUMO gap. The polarizability and hyperpolarizabilities of the complexes indicate that they are good candidates for NLO materials. Molecular electrostatic potential (MEP) maps identified electrophilic and nucleophilic sites on the surfaces of the complexes. TDDFT and NBO analyses provided insights into electronic transitions, bonding, and stabilizing interactions within the studied complexes. DPA and PDTC exhibited largerHOMO-LUMO gapsand more negative electrostatic potentials compared to their metal complexes suggesting the higher reactivity. Ligands (DPA and PDTC) had absorption spectra in the range of250nm to 285nm while their complexes spanned250nm to 870nm. These bands offer valuable information on electronic transitions, charge transfer and optical behavior. This work enhances our understanding of the electronic structure and optical properties of these complexes. Gaussian16 program was used for the optimization of all the compounds. B3LYP functional in combination with basis sets, such as LanL2DZ for Zn, Ni and Cu while 6-311G** for other atoms like C, H, O, N, and S was used. Natural bond orbital (NBO) analysis is carried out to find out how the filled orbital of one sub-system interacts with the empty orbital of another sub-system. The ORCA software is used for computing spectral features along with the zeroth order regular approximation method (ZORA) to observe its relativistic effects. TD-DFT study is carried out to calculate the excitation energy by using B3LYP functional.

Precise control of platinum coordination environment on fullerene-derived catalysts for oxygen reduction reaction

The interaction between catalysts and supports is recognized as a crucial factor influencing catalytic activity and stability. However, the carbon materials, which have been widely employed as the support at present, encounter challenges including intricate composition and the difficulty of precise control. In this study, the fullerene-derived carbon materials serve as support to electrocatalysts with low platinum. Fullerene-based materials, as the only carbon material with a well-defined molecular structure, have a controllable active site structure, which can provide a reaction model for studying metal-support interactions. Four kinds of fullerene-derived catalysts such as Pt/fullerene, Pt/nitrogen-doped fullerene, Pt/sulfur-doped fullerene, and Pt/phosphorus-doped fullerene, were synthesized. Once the coordination environment of the Pt particles was controlled, thus their catalytic performance was modulated. Despite a platinum loading of only 4.2%, Pt/N-fullerene demonstrates superior oxygen reduction activity and stability compared to commercial Pt/C (20%). Density functional theory calculations show that the introduction of heteroatoms can change the surface charge distribution of fullerenes, in which N-fullerene has a more negative electrostatic potential and can effectively anchor Pt. This research establishes a foundation for understanding the catalysts-support interaction and further precise control of the coordination environment of Pt. This provides new insights for designing efficient ORR catalysts.

Microstructure‐ionisation potential relationship analysis for understanding the molecular ionisation difference of natural esters during the impulse discharge via DFT calculation

AbstractUnderstanding the impulse discharge behaviour of natural ester (NE) is crucial for its safe application in high‐voltage transformers. The ionisation potential (IP) of triglycerides plays a significant role in the process of molecular ionisation during impulse discharge for NE. The correlation coefficients between molecular size, frontier orbital, electrostatic potential, polarity, and IP were analysed. And the quantitative microstructure‐IP model for triglycerides were built, which revealed that IP is strongly related to the highest occupied molecular orbital (HOMO) energy EHM, as well as the average value of positive electrostatic potential Vp(+), the average value of negative electrostatic potential Vp(−), and the surface area of negative electrostatic potential S(−). The HOMO and negative electrostatic potentials of saturated triglycerides are predominantly linked to the carbonyl O atoms. Conversely, in unsaturated triglycerides, the influence of C=C double bonds on HOMO and negative electrostatic potentials is more pronounced. Therefore, the IP of unsaturated NE with C=C bonds is lower than that of saturated NE, rendering it more susceptible to ionisation under a strong electric field which is unfavourable for impulse breakdown voltage. The structure‐property correlation analysis is valuable for understanding ionisation mechanism during the impulse discharge breakdown of NE at the microscopic level.

Critical Roles of Acidic Residues in Loop Regions of the Structural Surface for the Salt Tolerance of a GH39 β-d-Xylosidase.

Xylan is the main component of hemicellulose. Complete hydrolysis of xylan requires synergistically acting xylanases, such as β-d-xylosidases. Salt-tolerant β-d-xylosidases have significant application benefits, but few reports have explored the critical amino acids affecting the salt tolerance of xylosidases. Herein, the site-directed mutation was used to demonstrate that negative electrostatic potentials generated by 19 acidic residues in the loop regions of the structural surface positively correlated with the improved salt tolerance of GH39 β-d-xylosidase JB13GH39P28. These mutants showed reduced negative potentials on structural surfaces as well as a 13-43% decrease in stability in 3.0-30.0% (w/v) NaCl. Six key residue sites, D201, D259, D297, D377, D395, and D474, were confirmed to influence both the stability and activity of GH39 β-d-xylosidase. The activity of the GH39 β-d-xylosidase was found promoting by SO42- and inhibiting by NO3-. Values of Km and Kcat/Km decreased aggravatedly in 30.0% (w/v) NaCl when mutation operated on residues E179 and D182 in the loop regions of the catalytic domain. Taken together, mutation on acidic residues in loop regions from catalytic and noncatalytic domains may cause the deformation of catalytic pocket and aggregation of protein particles then decrease the stability, binding affinity, and catalytic efficiency of the β-d-xylosidase.

An efficient copper(II) salamo-based complex fluorescence chemosensor for detecting sulfide ions: Structure exploration and practical application

A novel salamo-based fluorescent chemical sensor l-Cu2+ was designed and prepared via the reaction of H2L and Cu(OAc)2·H2O. The whole research has found that Cu(II) atom in the complex crystal are located in the N2O2 cavity of H2L, forming a four-coordination system. Hirshfeld surface analysis confirmed the presence of hydrogen bonding and π···π stacking interactions. As a probe molecule, l-Cu2+can selectively and sensitively detect S2- without interference from other ions, and can be effectively used within the biological pH range. In addition, DFT theoretical calculations and molecular electrostatic potential analysis (ESP) were used to investigate the electron cloud density and positive and negative electrostatic potentials inside the probe, as well as the mechanism for identifying sulfur ions. Finally, the probe l-Cu2+has shown good practical application effects and can recognize S2− in three different water samples. It can also be used as a qualitative detection strip. l-Cu2+complex possesses excellent application prospect in bacteriostasis.

Water-Resistant, Scalable, and Inexpensive Chiral Metal–Organic Framework Featuring Global Negative Electrostatic Potentials for Efficient Acetylene Separation

Water-Resistant, Scalable, and Inexpensive Chiral Metal–Organic Framework Featuring Global Negative Electrostatic Potentials for Efficient Acetylene Separation

Columnar Liquid Crystal Enables In‐Situ Dispersing of Excess PbI2 Crystals for Efficient and Stable Perovskite Solar Cells

AbstractExcess PbI2 has been deemed as indispensable component to boost the efficiency of perovskite solar cells (PSCs). However, the random aggregation of PbI2 crystals seriously disturbs the transport behavior of the carrier and accelerates the degradation of perovskite film. Herein, an effective strategy to in situ disperse excess PbI2 crystals via the columnar liquid crystal (T6TE) is developed. Rapid self‐assembly induced by intermolecular π–π interaction enables T6TE to form the ordered columnar phase with “edge‐on” orientation in perovskite. The columnar T6TE can efficiently disperse excess PbI2 crystals with the merits of strong negative electrostatic potential and highly steric hindrance. Target perovskite deserves preferable crystallization and reconstructed surface, leading to reduced defects density, less residual stress, and efficient carrier transport. Besides, the T6TE significantly impedes the degradation of perovskite film and the formation of Pb0 defects. Resultant T6TE‐assisted PSCs achieve the champion power conversion efficiency (PCE) of 24.27% for mixed Cs+‐FA+‐MA+ perovskite. The PCE of a larger area (1 cm2) device reaches to 21.50%. The unencapsulated device maintains ≈85% of the initial PCE after 1500 h storage in the atmosphere with 40–60% relative humidity. This work provides a new strategy to in situ disperse excess PbI2 by incorporating columnar liquid crystal for the first time.

Endowing the Operability of Supercapacitors at High Temperatures by Regulating the Solvation Structure in Dilute Hybrid Electrolyte with Trimethyl Phosphate Cosolvent.

The redox stabilities of different oxygen donor solvents (C═O, P═O and S═O) and lithium salt anions for supercapacitors (SCs) electrolytes have been compared by calculating the frontier molecular orbital energy. Among six lithium difluoro(oxalate)borate (LiDFOB)-based mono-solvent electrolytes, the dilute LiDFOB-1,4-butyrolactone (GBL) electrolyte exhibits the highest operating voltage but suffers from electrolyte breakdown at elevated temperatures. Trimethyl phosphate (TMP) exhibits the highest redox stability and a strongly negative electrostatic potential (ESP), making it suitable for promoting the dissolution of LiDFOB as expected. Therefore, TMP is selected as a co-solvent into LiDFOB-GBL electrolyte to regulate Li+ solvation structure and improve the operability of electrolytes at high temperatures. The electrochemical stable potential window (ESPW) of 0.5m LiDFOB-G/T(5/5) hybrid electrolyte can reach 5.230 V. The activated carbon (AC)-based symmetric SC using 0.5m LiDFOB-G/T(5/5) hybrid electrolyte achieves a high energy density of 54.2Whkg-1 at 1.35kWkg-1 and the capacitance retention reaches 89.2% after 10000 cycles. The operating voltage of SC can be maintained above 2V when the temperature rises to 60°C.

Electrostatic Impact of Brefeldin A on Thiocyanate Probes Surrounding the Interface of Arf1-BFA-ARNO4M, a Protein-Drug-Protein Complex.

Protein-protein interactions regulate many cellular processes, making them ideal drug candidates. Design of such drugs, however, is hindered by a lack of understanding of the factors that contribute to the interaction specificity. Specific protein-protein complexes possess both structural and electrostatic complementarity, and while structural complementarity of protein complexes has been extensively investigated, fundamental understanding of the complicated networks of electrostatic interactions at these interfaces is lacking, thus hindering the rational design of orthosterically binding small molecules. To better understand the electrostatic interactions at protein interfaces and how a small molecule could contribute to and fit within that environment, we used a model protein-drug-protein system, Arf1-BFA-ARNO4M, to investigate how small molecule brefeldin A (BFA) perturbs the Arf1-ARNO4M interface. By using nitrile probe labeled Arf1 sites and measuring vibrational Stark effects as well as temperature dependent infrared shifts, we measured changes in the electric field and hydrogen bonding at this interface upon BFA binding. At all five probe locations of Arf1, we found that the vibrational shifts resulting from BFA binding corroborate trends found in Poisson-Boltzmann calculations of surface potentials of Arf1-ARNO4M and Arf1-BFA-ARNO4M, where BFA contributes negative electrostatic potential to the protein interface. The data also corroborate previous hypotheses about the mechanism of interfacial binding and confirm that alternating patches of hydrophobic and polar interactions lead to BFA binding specificity. These findings demonstrate the impact of BFA on this protein-protein interface and have implications for the design of other interfacial drug candidates.

Occurrence Modes of AAEMs (Na+ and Ca2+) and the Effect on the Molecular Structures of Zhundong Coal via Quantum Chemistry.

Zhundong coal is known for its high content of alkali and alkaline earth metals (AAEMs), which greatly influences coal processing and utilization. To reveal the occurrence modes and the effect of AAEM ions on the molecular structures of Zhundong coal, the previously constructed molecular structure models of vitrinite-rich and inertinite-rich Zhundong coal (ZD-V and ZD-I) were selected to simulate using quantum chemical methods. By focusing on Na+ and Ca2+, the adsorption capacity at different adsorption sites was investigated based on the density functional theory (DFT), and the effects of adsorption of Na+ and Ca2+ on nearby atomic charges, chemical bonds, and molecular orbitals were investigated. Results show that compared with ZD-I, ZD-V contains a more negative electrostatic potential (ESP) distribution and lower bond order, indicating that vitrinite contains more adsorption sites for AAEM ions and exhibits stronger chemical reactivity. Na+ and Ca2+ are easily adsorbed to the most negative ESP with the optimal adsorption site near the carbonyl group (C=O). Compared with adsorbed Na+, Ca2+ has a smaller adsorption distance from the molecule and a higher adsorption energy. Ca2+ can transfer more charge than Na+ and has more affinity with the coal molecule. Ca2+ at all adsorption sites is bound to organic molecules by chemisorption, which also reveals the reason for the low water-soluble Ca content in coal at the molecular level. Adsorption of AAEM ions has a more significant effect on the chemical bond of oxygen-containing functional groups near AAEM ions compared to the overall molecular fragments, which makes the nearby chemical bonds (C-O/C=O) decrease in bond order and increase in bond length. Ca2+ makes the nearby chemical bonds more prone to break than Na+. Additionally, Ca2+ has a more significant impact on the energy gaps (ΔEgap) compared to Na+. Adsorption of Ca2+ near the carbonyl and carboxyl groups leads to a significant decrease in ΔEgap, indicating an enhanced chemical reactivity of coal molecular fragments.

Quantum chemical study on the catalytic debromination mechanism of brominated epoxy resins

The study employed Density Functional Theory (DFT) to investigate the catalytic debromination mechanism of brominated epoxy resins (BERs) by iron (Fe) and copper (Cu) catalysts. By introducing electric field (EF), intramolecular electron transfer and polarization effects on BERs debromination were explored and experimentally validated. Results indicated that the bond dissociation energy (BDE) of the C-Br bond was 312.27 kJ/mol without catalysis, while with Fe, Cu, and EF, it was 114.47 kJ/mol, 94.85 kJ/mol, and 292.59 kJ/mol, respectively, enhancing reactivity. EF parallel to the C-Br bond and oriented toward the C atom, altered electrostatic potential and dipole moment around C-Br bond, leading to 68.60% and 50.19% increment in electronic contribution difference and molecule polarity, respectively, thereby reducing the C-Br BDE. Fe and Cu facilitated electron transfers with BERs, inducing reactions between their negative electrostatic potentials and Br's positive potential, changing electron sharing, resulting in 19.87% and 12.11% increase in polarity, respectively, and further BDE reduction. Structural modifications by the EF and catalysts also intensified van der Waals forces with bromine atoms and decreased spatial hindrance, collectively making C-Br bond breakage easier. Experiments revealed the EF enhanced BERs' debromination efficiency but hindered Fe/Cu's catalysis at lower temperatures.

Thermal stability and thermal decomposition mechanism of octamethyltrisiloxane (MDM): Combined experiment, ReaxFF-MD and DFT study

The thermal stability and decomposition mechanism of octamethyltrisiloxane (MDM) were studied using a combination of experimental, ReaxFF simulation, and DFT calculation techniques. After heating MDM for 24 h at 250 °C and 1 MPa, the signature product CH4 was detected, along with liquid products such as hexamethyldisiloxane (MM) and decamethyltetrasiloxane (MD2M). The decomposition rate of MDM remained relatively constant in the temperature range of 250 °C–320 °C but exhibited a sharp increase at 350 °C. Higher pressure was found to promote MDM polymerization. The oxygen (O) atoms displayed a large negative electrostatic potential, while the hydrogen (H) and silicon (Si) atoms exhibited a large positive potential. The electrostatic interaction facilitated the rearrangement reactions, with O and carbon (C) atoms being the most reactive for electrophilic and free radical reactions. The thermal decomposition of MDM initiated with the cleavage of Si–C bonds. Hydrogen extraction reactions between methyl radicals and MDM, as well as Si–O bond rearrangement reactions of demethylated radicals with MDM, further promoted MDM decomposition and the formation of CH4 and siloxane oligomers. These findings are significant for the safe application of MDM as a working fluid in ORC system.

Interactions between fluorocarbon surfactant and coal dust at macro, meso and molecular scales and their applications in coal dust control

Surfactants play an important role in the field of coal dust prevention, among which fluorocarbon surfactants have the advantages of low surface tension and have the potential to become mine dust suppressants. In this study, the wettability of fluorocarbon surfactant (OBS) on coal dust was studied from macro experiments, meso dust mist coupling and micro molecular simulation. The results showed that the surface tension of 0.06% OBS was as low as 17.6 mN/m, and the median particle size of coal dust reached 60.25 μm after wetting coal dust. Coal dust particles are easier to bond with each other into large particles, thus promoting settlement; During the meso collision between droplets and coal dust particles, OBS droplets showed excellent wetting and spreading effect, and the droplet state was stable, and the optimal spraying velocity was determined to be 20–30 m/s; At the molecular level, the diffusion coefficient of water molecules in the OBS system is minimally 0.46 Å2/ps, indicating a strong ability to constrain water molecules. The strength and energy of the hydrogen bonds formed with water molecules were greater than those of hydrocarbon surfactants, resulting in the best adsorption of water molecules. Additionally, it was found that the law of attractive and competitive adsorption of different surfactants in wetting coal dust is based on the difference in positive and negative electrostatic potential, where the greater the difference, the stronger the interaction. This provides a theoretical reference for judging the wetting performance of different surfactants at the molecular level.

Porphyrin-based hydrogen-bonded organic framework for visible light driven photocatalytic removal of U(VI) from real low-level radioactive wastewater

The reduction of soluble U(VI) to insoluble U(IV) precipitates by visible light is an environmentally friendly and highly effective strategy to remove uranium from uranium-containing radioactive wastewater. Herein, a porous hydrogen-bonded organic framework (HOF) of UPC-H4a was self-assembled by intermolecular hydrogen bonds of 5,10,15,20-tetra(4-(2,4-diaminotriazine)phenyl) porphyrin to remove U(VI) from aqueous solution. UPC-H4a has high crystallinity with permanent porosity, excellent photocatalytic property, good chemical stability, and strong photocatalytic reducibility. The experiments showed that UPC-H4a removed 98.18% of U(VI) after illumination for 120 min, with high selectivity, strong ion interference resistance, and good reusability. A real low-level radioactive wastewater was employed to estimate the potential of UPC-H4a for practical application and its removal rate can reach 66.14% in the presence of redox competing metal ions, exhibiting great potential for practical application. The DFT calculations and EPR spectra revealed that a more negative electrostatic potential of DAT-porphyrin and the formed intermolecular hydrogen bonds in UPC-H4a can facilitate the participation of photogenerated electrons in the O2/∙O2– reaction, and the radical of ∙O2– was proved to be the critical participant in U(VI) photoreduction. The discovery of UPC-H4a in this work will help to develop more potential applications of HOFs as photocatalysts in radioactive wastewater treatment.

Adsorption performance and mechanisms of MgO-modified palygorskite/biochar composite for aqueous Cd (II): Experiments and theoretical calculation

The treatment of Cd2+ pollution in water has been a hot topic of research, while the studies for the preparation and application of biochar composites to treat Cd2+ and the corresponding micro-mechanisms were still lacking. In this study, a novel MgO-modified palygorskite/biochar derived from rice straw composite (MPBC) was synthesized to remove Cd2+ in the aqueous solution. Batch experiments were conducted to evaluate the adsorption ability for Cd2+ on MPBC. The results showed that the maximum adsorption capacity of MPBC was 441.1 mg/g, which was 4.6 times higher than that of the original biochar (BC). Adsorption mechanisms were clarified combine systematic characterization and density functional theory (DFT) calculations. Precipitation, complexation, ion exchange, and Cd-π interaction were the main adsorption mechanisms, and the contribution of the ion exchange, compared with 12.08% of BC, increased to 37.82%. The O atom of the MgO group performed negative electrostatic potentials as an electrophilic active site. The nucleophilic Cd tends to transfer electrons to the electrophilic O atom of the MgO group. Furthermore, the density of state (PDOS) identified that hybrid overlap occurred between MgO and Cd, and a new chemical bond was formed in the adsorption process. Overall, this work offers a new approach to removing aqueous Cd2+ and uses biowaste to create a sustainable environment.

Preparation and Properties of Three Plasticiser-Free Novel Di-benzo-18-Crown-6 Aldimine-Derived Lead(II) Ion-Selective Electrodes

Three novel dibenzo-18-crown-6 aldimines were successfully synthesised and structurally characterised via various spectroscopic methods (1H,13H NMR, FT-IR) and their solution phase lead binding behaviours probed via absorption spectroscopy, the results are supported by Density Functional Theoretical (DFT) modelling. These methods revealed that the asymmetric nature of these compounds is such that at equilibrium the ether cavity adopts an open configuration where the constituent oxygen atoms exhibit a highly negative electrostatic potential; hence, they spontaneously (ΔG~−58 kJ mol−1) interact/bind aqueous lead ions to form stable 2:1 metal–ligand complexes. As indicated by cyclic and square voltammetry studies, all compounds are redox active and polymerise relatively easily onto a platinum surface to form a multi-layered lead Ion-selective Membrane (ISM), the structure of which is confirmed by Scanning Electron Microscopy (SEM) and Electrochemical Impedance Spectroscopy (EIS). These novel Ion-selective Electrodes (ISEs), as characterised by Differential Pulse Anodic Stripping Voltammetry (D PASV), allow selective electrochemical detection and quantification of lead at concentrations as low as 10 ppm, over a range of 15–60 ppm, with only minimal interference from mercury(II) and aluminium(III) ions at a 1:1 analyte-interferent ratio.