Molecular Structure Research Articles

Molecular dynamics simulation of solvation behavior and thickening properties of modified siloxanes in supercritical carbon dioxide under different pressure and temperature

Supercritical carbon dioxide (ScCO2) fracturing fluids have been limited in their application in unconventional reservoirs due to their weak proppant-carrying capacity resulting from their low viscosity. Consequently, numerous scholars have focused on modifying siloxanes to enhance their solubility and thickening performance in ScCO2. In this paper, the cohesive energy density, interaction energy, radial distribution function, shear viscosity and electrostatic potential distribution of modified siloxane with ScCO2 were calculated using molecular dynamics simulation. The effects of different temperatures and pressures on the dissolution and thickening ability of modified siloxanes in ScCO2 were investigated.The simulation results indicate that high temperature and low pressure have limited effects on promoting the solubility of modified siloxanes in ScCO2, with temperature exerting a more significant influence on solubility behavior than pressure. Additionally, PD4H+TMPTMA is less soluble in ScCO2 compared to PD4H+TAIC. The binding energy of ScCO2 and modified siloxanes decreases with increasing temperature but increases with increasing pressure. Van der Waals interactions and electrostatic interactions play decisive roles in the solubility of modified siloxanes in ScCO2. Finally, the thickening mechanism of modified siloxanes in ScCO2 was elucidated based on molecular structure and binding energy interactions.In summary, this paper aims to provide options and assistance in synthesis of better ScCO2 thickeners for unconventional reservoir fracturing applications through the study of modified siloxanes.

Towards improving the characteristics of high-energy pyrazines and their N-oxides.

Based on the methods of quantum chemistry and atom-atom potentials, the molecular and crystal structure of a number of high-energy pyrazines was modeled: unsubstituted diazines, as well as fully nitrated 1,4-diazabenzenes, their oxides and polymorphs. The enthalpies of formation, densities of molecular crystals, and some performance characteristics of these compounds were determined. The parameters of decomposition of substances were estimated. It has been established that tetranitropyrazine-1,4-dioxide has maximum energy content and excellent performance characteristics, which determine the prospects for using this compound as a high-energy one in the considered series of compounds. In this work, DFT calculations were conducted through the software Gaussian 09 using B3LYP functional with basis set aug-cc-PVDZ and the Grimme dispersion correction D2. For crystal structure optimization, the atom-atom potential methods with PMC program (Packing of Molecules in Crystal) were used. Charges for molecular electrostatic potential were fitted by FitMEP and enthalpies of formation in gas phase were assessed by G3B3.

Exploration of electrical conduction mechanisms via modulating sintering period of La0.67Ca0.33MnO3 films in various phase regions

Perovskite manganese oxide films have garnered significant attention due to their unique and diverse physical properties. In this work, La0.67Ca0.33MnO3 (LCMO) films are prepared on LaAlO3 (00l) substrates using the sol−gel spin coating method with varying sintering period (Ps). By optimizing Ps, improvements were observed in the films’ structure, morphology, ionic valence, and temperature−dependent resistivity. The reduction in Mn−O bond length and the increase in Mn−O−Mn bond angle change the degree of MnO6 distortion, resulting in an increased eg bandwidth. As Ps increased, the LCMO films exhibited better crystalline quality. The improved Mn4+/Mn3+ ratio strengthened the double exchange effect, facilitating the carrier hopping of the eg electrons. Analyses of various electrical conduction mechanisms showed that optimized electron scattering behavior, reduced hopping distance, energy and theoretical Curie temperature collectively enhance the temperature coefficient of resistivity (TCR) of LCMO films under optimal Ps. The TCR of the LCMO films reached a maximum value (31.64 % K−1) at Ps = 18 min. These findings offer valuable insights into the main electrical conduction mechanisms in both metallic and semiconducting phases, providing a deeper understanding of the underlying physical processes and offering experimental guidance for optimizing the electrical transport properties of perovskite films.

Electronic, thermodynamic, NLO, and spectroscopic properties of OAFLC compounds via DFT: A focus on 1F6B, 1F6Bi, 1F6BiN, and 1F6BN

This study presents a comprehensive quantum mechanical investigation of four novel liquid crystalline compounds: 1F6B, 1F6Bi, 1F6BiN, and 1F6BN. Using Density Functional Theory (DFT) with the B3LYP functional and 6-311G(d,p) basis set, we optimized the molecular geometries and analyzed their electronic and vibrational properties. Atomic Polar Tensor (APT) charge analysis showed significant charge distributions. Electrostatic potential (ESP) mapping identified potential reactive sites, while Electron Localization Function (ELF) and Localized Orbital Locator (LOL) analyses depicted the electron density distributions. Thermodynamic parameters indicated the compounds’ vibrational stability and responsiveness to thermal changes. Non-linear optical (NLO) properties were characterized by significant dipole moments and polarizabilities, suggesting potential in optoelectronic applications. Frontier molecular orbital analysis indicated stability with HOMO-LUMO gaps ranging from 4.15 to 4.64 eV. UV–Vis spectra revealed key electronic transitions, while Raman spectroscopy detailed various vibrational modes. The study offers valuable insights into the molecular behavior of these compounds, laying the groundwork for their future applications in material science and advanced technologies.

Investigating the Inhibition of Diindolylmethane Derivatives on SARS-CoV-2 Main Protease.

The SARS-CoV-2 main protease (Mpro) is an essential enzyme that promotes viral transcription and replication. Mpro conserved nature in different variants and its nonoverlapping nature with human proteases make it an attractive target for therapeutic intervention against SARS-CoV-2. In this work, the interaction mechanism between Mpro and diindolylmethane derivatives was investigated by molecular docking, enzymatic inhibition assay, UV-vis, fluorescence spectroscopy, and circular dichroism spectroscopy. Results of IC50 values show that 1p (9.87 μM) was the strongest inhibitor for Mpro in this work, which significantly inhibited the activity of Mpro. The binding constant (4.07 × 105 Lmol-1), the quenching constant (5.41 × 105 Lmol-1), and thermodynamic parameters indicated that the quenching mode of 1p was static quenching, and the main driving forces between 1p and Mpro are hydrogen bond and van der Waals force. The influence of molecular structure on the binding is investigated. Chlorine atoms and methoxy groups are favorable for the diindolylmethane derivative inhibitors of Mpro. This work confirms the changes in the microenvironment of Mpro by 1p, and provides clues for the design of potential inhibitors.

Rapid carbonate precipitation induced by carbamate coating: A new approach to form impermeable thin barrier and its mechanism

Various coating strategies have been explored in the past to prevent the ingress of aggressive substances into concrete. However, either the durability or performance is still far from satisfaction. Here, carbamate solutions were prepared by pre-absorbing CO2 into amino acid salts (AASs) to carbonize the surface of cementitious materials. The high concentration of carbonate ions provided by the carbamate induced rapid surface carbonation, resulting in the formation of an AAS-CaCO3 composite barrier with a thickness of 2–3 μm and possessing high micromechanical properties. Additionally, it was observed that the barrier's effectiveness depends on the molecular structures of the amino acids employed. Coatings formed by arginine-based carbamates demonstrated excellent performances, likely due to the highly compacted calcite particles they produced. This easy-to-operate and effective strategy has the potential to open new avenues for the development of highly durable and impermeable coating barriers for practical applications.

Differences in the molecular structure of curcumin and its breakdown products affect their inhibitory effect on pepsin: Kinetic and protein spatial conformation study

Curcumin, a natural phenolic compound with various bioactivities, is easily decomposed into stability ferulic acid and vanillin molecules. Whether the functional equivalence of decomposition products can match that of curcumin is a matter worth attention. In this work, the inhibition and interaction of curcumin and its decomposition products on pepsin were studied. The inhibition by curcumin and ferulic acid belonged to competitive inhibition, the quenching types were static quenching with spontaneous process. Binding energies of curcumin, ferulic acid and vanillin were -8.33±0.14, -7.88±0.09 and -6.12±0.08 kcal/mol, respectively, through H-bonds and hydrophobic interactions. All molecules significantly changed the secondary structure of pepsin and reduced the deformation temperature about 15 °C. The results show that better inhibition on pepsin from curcumin than ferulic acid, whereas vanillin did not show inhibition. The results provided the experimental basis for curcumin as potential inhibitors of pepsin in special diets.

Fabrication, Structural, DFT, Biological and Molecular Docking Studies of Fe(III), Ni(II), and Cu(II) Complexes Based on Schiff-base derived from benzene-1,4-diamine and 2-hydroxy-1-naphthaldehyde

This study presents the design & comprehensive characterization of three novel metal complexes derived from a Schiff base compound (H2PDN) synthesized from benzene-1,4-diamine and 2-hydroxy-1-naphthaldehyde, coordinated with Fe (III) (FePDN), Ni (II) (NiPDN), & Cu (II) (CuPDN). Structures of both the H2PDN ligand & its metal complexes were proposed utilizing various analytical methods, having elemental analysis, ultraviolet-visible spectroscopy, mass spectrospcopy, infrared spectroscopy, magnetic properties, conductivity measurement, & thermal analysis. The obtained data revealed octahedral geometries for both FePDN and CuPDN complexes, denoted as [Fe2(PDN)(H2O)4(Cl)4] and [Cu2(PDN)(H2O)6(Cl)2], respectively, while the NiPDN complex exhibited a distorted tetrahedral structure, represented as [Ni2(PDN)(H2O)2(Cl)2]. Density functional theory (DFT) computations were employed to validate the molecular structures & explore quantum chemical parameters of both H2PDN & its metal complexes. The synthesized H₂PDN Schiff base and its metal complexes (FePDN, NiPDN, CuPDN) showcased significant antimicrobial, anti-inflammatory, and antioxidant activities. NiPDN exhibited the highest inhibition zone against P. aeruginosa (21.44±0.28 mm) and S. aureus (19.37±0.40 mm), while CuPDN showed strong inhibition against E. coli (18.42±0.13 mm). NiPDN demonstrated excellent antibacterial efficacy with a low MIC against B. cereus (21.00±0.98 μM), and CuPDN displayed potent anti-inflammatory (IC50: 121.65 μM) and antioxidant activity (IC50: 84.7±0.77 μM). These results indicate the therapeutic potential of the H₂PDN complexes. Molecular docking studies targeting specific proteins (2VF5 for Escherichia coli, 3CKU for Aspergillus flavus, 5IKT for Human Cyclooxygenase-2, & 5IJT for human peroxiredoxin 2) were performed to assess the binding affinities & interactions of H2PDN & its metal complexes. The results propose promising potential for the application of H2PDN and its metal complexes as novel therapeutic agents with diverse biological activities.

Twisted Benzothieno-Fused BOPHY Dyes as Triplet Photosensitizers with Long-Lived Triplet Excited States.

The synthesis of a series of photostable [b]-benzothieno-fused BOPHY derivatives is reported via one-pot condensation of formylated isoindoles or formylindoles with hydrazine and subsequent boron complexation. These dyes show strong absorption in the deep red region and acceptable fluorescence quantum yields (∼30%). The two fused benzothiophene moieties are slightly deviated from the BOPHY core (with dihedral angles of 6.1 and 10.2°). This slightly twisted conformation brings an enhanced spin-orbit coupling and a reduced energy band gap between singlet and triplet states. The enhanced intersystem cross process endows these series of dyes with a good singlet oxygen quantum yield (up to 63%), a high triplet-state quantum yield (up to 78%), and a long lifetime value (up to 127 μs). Density functional theory calculations indicate that the transition from S1 to T2 states is crucial for triplet-state formation, highlighting their high efficiency in intersystem crossing. The calculated triplet electron spin surface reveals a widespread distribution of triplet states across the conjugated molecular structure, which enhances the Dexter mechanism for triplet energy transfer in these BOPHY photosensitizers. These findings are helpful for thorough understanding of the fundamental ISC process and developing triplet photosensitizers.

Increase of bridge length by ingenious grafting of ester chains, imparting epoxy resins superb thermal, smoke suppression, gas-phase flame retardancy, and mechanical properties

While bifunctional synergistic flame retardants have demonstrated efficacy in enhancing the fire safety of epoxy resins (EPs), the grafting of specific functional monomers into flame retardant molecules, elucidating their mechanisms of action through comparative analysis, and concurrently achieving a delicate balance among flame retardancy, heat resistance, and mechanical toughness remains a significant challenge. Herein, this research present an innovative strategy to derive a novel sulfur-based bifunctional flame retardant, DSTA, based on the structure of the original flame retardant, DST, by grafting the ester chains to increase the bridge length of the molecular structure. As expected, the addition of flexible ester chains enabled DSTA to have a very high initial decomposition temperature and the heat-resistance index. DSTA can be used in low dosage compared to DST, enabling EP to achieve UL-94 V-0 rating. Combustion behavior showed that DSTA had the best ability to heat and smoke suppression for EP, and had faster response speed and higher fire growth index. Notably, pyrolysis volatiles tested on DSTA revealed that the ester chains can pyrolysis to release large amounts of CO2, which occurs in the early stages of pyrolysis and works together with other N-containing inert gases and P-containing radicals in the gas-phase to efficiently extinguish flames. Meanwhile, DSTA improves all mechanical properties of EP, which was attributed to the presence of ester chains. In summary, this work presents a new strategy for examining the impact of specific functional groups on the flame retardant mechanisms of EP.

Assessing the potential for upscaling the continuous production of lignin oils through reductive catalytic depolymerization

Lignin represents up to one third of lignocellulosic biomass and is a sustainable carbon source available at a sufficient scale to replace an impactful amount of fossil resources when converted into materials and chemicals. The molecular structure of lignin renders it ideal to obtain renewable aromatic building blocks for the polymer industry. Nevertheless, in polymeric form, lignin poses serious challenges for material applications and chemical conversion, namely poor solubility, and low reactivity. This problem can be circumvented by depolymerization of isolated lignins. To meet the demand for renewable aromatic building blocks, it is crucial to utilize technical lignin streams generated on large scale. This will eventually allow the development of continuous, high-throughput processes which are required for viable industrial-scale operations. Our work demonstrates for the first time that “technical grade” hydrolysis lignin from an operating biorefinery can be successfully subjected to continuous reductive catalytic depolymerization (RCD) in a packed bed reactor using a commercially available Pd/Al2O3 catalyst. The impact of catalyst amount, feed concentration (in methanol), and temperature with regards to process stability and product quality was investigated. The product was characterized by NMR, GPC, and GC-FID. Feed concentrations up to 7 wt% could be continuously processed for 77 h at 200 °C whereas at 225 °C, the operation time was restricted to 21 h. In all cases, a stable output was obtained over time in terms of molar mass, OH-group distributions, and monomer content. At 200 °C, carbon yields above 90 % of the soluble lignin fraction were feasible.

The simultaneous application of fulvic acid and protein hydrolysate biostimulants enhances cucumber responses to Fe deficiency

Iron (Fe) is widely recognized as a critical factor in limiting crop production; however, eco-friendly strategies to address its deficiency are still required. The use of biostimulants has displayed promising results in mitigating Fe deficiency. Our hypothesis was that the combined application of two biostimulants with distinct molecular structures - fulvic acid (FA) and protein hydrolysate (PH) - could be more effective than the use of a single compound. The simultaneous presence of FA and PH (MIX) in a Fe-free nutrient solution led to a redistribution of endogenous Fe, resulting in a higher leaf SPAD index. Furthermore, the addition of FeCl3 as a Fe source (resupply) in MIX-treated plants enhanced the biostimulant effect, as evidenced by increased dry root and shoot weight and a more developed root system. In addition, the expression of Strategy-I-related genes, CsFRO1 and CsIRT1, remained elevated. These effects can be attributed to improved interaction between the roots and biostimulants through the formation of the FA-PH complex, as demonstrated by circular dichroism and isothermal titration calorimetry analyses.

Research on the microscopic mechanism and model applicability differences of CH4 and CO2 adsorption based on molecular dynamics

To verify the accuracy and rationality of the molecular simulation model, the microscopic mechanism of gas adsorption was analyzed and clarified from a microscopic perspective. The effect of molecular models created by direct construction and supercell expansion on the adsorption capacities of CH4 and CO2 has been analyzed. Eight coal-based molecular configurations were created to simulate the isothermal adsorption process of CH4 and CO2 using various coal-based molecular configurations. Using physical experiments, the validity of different construction methods for coal-based molecular structures was verified. The direct construction method was chosen to simulate the effect of various coal-based molecular numbers on the adsorption capacity of CH4 and CO2. The results show that the adsorption capacity of CO2 on coal is greater than that of CH4. The isothermal adsorption curves of CH4 and CO2 in coal-based molecular systems constructed using different methods reveal that the adsorption of methane on coal molecules adheres to the Langmuir monolayer adsorption theory. The adsorption sites for methane increase with the rise in free volume. The structure directly constructed and the supercell expansion directly determines the amount of methane adsorbed by each coal based molecule. The adsorption constants of CH4 and CO2 on the supercell extended structure are more volatile than those on the directly constructed structure, and the structure constructed directly for different coal based molecules is better than the supercell extended structure. The simulation using the direct construction method shows that as the number of coal-based molecules in the molecular configuration increases, The isothermal adsorption quantities of CH4 and CO2 increase linearly. The molecular configuration is not affected by the number of anthracite molecules. Molecular configuration is not affected by the number of anthracite molecules. The rationality of model construction has no obvious relationship with the number of coal based molecules.

Acceptor-acceptor′-acceptor type N-annulated perylenediimide dimeric acceptors at the outside-bay position: Synthesis and role of asymmetric 4,7-di(thien-2-yl)-5-fluorobenzothiadiazole linker

Acceptor-acceptor′-acceptor (A-A′-A) type N-annulation perylene diimide (PDI) dimeric acceptors possessed the fascinating merits but were ignored. Herein, two A-A′-A type N-annulated PDI dimers, termed as, DTBT-(PPDI-B)2 and DTFBT-(PPDI-B)2, in which the electron-deficient moieties 4,7-di(thien-2-yl)benzothiadiazole (DTBT) and monofluorinated 4,7-di(thien-2-yl)-5-fluorobenzothiadiazole (DTFBT) were selected as the central linkers and two N-annulation N-butyl-[1,12-b,c,d]pyrrole-N,Nʹ-bis(2-hexyldecyl)perylenediimide (PPDI-B) aromatic rings as the dual wings were explored. The annulation-free DTBT-(PDI-HD)2 was chosen as reference material. Owing to electron-donating of the newly formed pyrrolic aromatic ring, these studied N-annulated acceptors possessed the improved absorption and up-shifted ELUMO than those of the counterpart DTBT-(PDI-HD)2. Both of them exhibited the wide absorption spectra spanning from 300 nm to 700 nm, the similar aggregation and good photostability in solution. Monofluorinating the central benzothiadiazole linker gave the enhanced absorption, the down-shifted EHOMO and ELUMO, the reduced the dihedral angle from 9.09o to 3.64o between two N-annulated PPDI sub-planes and the enhanced solid stacking and aggregation. As a result, the N-annulation modification achieved the 0.16 V increased VOC, decreased JSC and FF, and thus the reduced PCE of 0.90%. Moreover, the 21.33% increased JSC of 3.64 mA cm‒2 and the 35.58% raised FF up to 42.68% were observed in the monofluorinated PTB7-Th:DTFBT-(PPDI-B)2-based device, synergistically contributing to an 62.22% elevated PCE of 1.46% in spite of a 0.01 V dropped VOC. This upgradation was predominantly profited from the increased absorption, the improved exciton dissociation, elevated electron mobility and improved microstructural morphology benefiting from introducing the asymmetric 4,7-dithienyl-5-fluorobenzothiadiazole. This work demonstrates that outside bay N-annulation strategy could tune the molecular structure, energy level and thus improve the voltage, and monofluorinating the central linker is an effective tactic for regulating the molecular configuration, aggregation, morphology and thus elevating the photovoltaic performance in the A-A′-A type N-annulated PDI dimeric acceptors.

Methylation modification is a poor prognostic factor in non-small cell lung Cancer and regulates the tumor microenvironment: mRNA molecular structure and function

Non-small cell lung cancer (NSCLC) is the most common and deadly type of lung cancer, and its poor prognosis is closely related to the complex interactions of the tumor microenvironment. Through methylation analysis of tumor tissue samples from NSCLC patients, combined with high-throughput sequencing technology, the methylation status and structural characteristics of mRNA molecules were studied. Bioinformatics tools were used to analyze the regulatory effects of methylation modification on mRNA expression and genes associated with the tumor microenvironment. The results showed that the methylation level of specific mRNA was significantly correlated with the expression changes of tumor microenvironment-related factors. In addition, methylation modification affected mRNA stability and translation efficiency, further altering the metabolic activity and immune escape capacity of tumor cells. The results showed that mRNA with high methylation level was significantly associated with poor prognosis. Methylation modification profoundly affects the tumor microenvironment and prognosis of non-small cell lung cancer by altering the structure and function of mRNA molecules.

A semi-empirical parameter predicting the sensitivity of energetic materials from external pressure

Measuring the ability of a material to absorb energy from an external stimulus is crucial for understanding the sensitivity mechanism of energetic materials (EMs). Based on this, a semi-empirical parameter, M, is proposed to measure the material’s ability to absorb energy from an external stimulus, which is closely related to zero-point energy and volume. In this work, taking the external pressures (P) of 0.1 and 1.0 GPa as examples, we calculate the value of M for 16 EMs, and discuss the relationship between M and the impact sensitivity of EMs (E50). Considering the indispensable influence of molecular structure on the impact sensitivity of EMs, 16 EMs are divided into Groups A and B according to their structure whether contains a benzene ring. We find that the correlation between M0 and E50 when P is 0.1 GPa is less than that when P is 1.0 GPa. Therefore, the parameter M0 has been modified by adding the initial zero-point energy, and the modified parameter is referred to as M∗. The correlation between M∗ and E50 is further improved compared with M0. In particular, for Group B, the correlation between M∗ and E50 is good, where R2 is 0.95 and PCCs is 0.97 when P is 1.0 GPa, and R2 is 0.87 and PCCs is 0.92 when P is 0.1 GPa.

Design, Characterization, and Bioactivity Evaluation of Novel Symmetrical N,N'-benzene-1,2-diylbis[1-(2-chloroquinolin-3-yl)methanimine] based metal complexes

This study presents the synthesis and characterization of two novel metal complexes derived from the symmetrical Schiff base N,N'-benzene-1,2-diylbis[1-(2-chloroquinolin-3-yl)methanimine] (OBCQ), coordinated with Nickel(II) (NiOBCQ) and Copper(II) (CuOBCQ). The structural elucidation of these complexes was achieved through a comprehensive suite of analytical techniques, including elemental analysis, UV-visible spectroscopy, mass spectrometry, infrared spectroscopy, magnetic susceptibility, conductivity measurements, and thermal analysis. The data confirm that both NiOBCQ and CuOBCQ adopt octahedral geometries, formulated as [Ni(OBCQ)(H₂O)₂(Cl)₂] and [Cu(OBCQ)(H₂O)₂(Cl)₂], respectively. Density Functional Theory (DFT) calculations were employed to validate the molecular structures and explore the quantum chemical parameters of OBCQ and its metal complexes. Additionally, in vitro assessments of anti-inflammatory and antioxidant activities revealed enhanced bioactivity for the metal complexes compared to the free OBCQ ligand. Molecular docking studies against key proteins (5IKT for Human Cyclooxygenase-2 and 5IJT for Human Peroxiredoxin 2) highlighted strong binding affinities and molecular interactions, suggesting that OBCQ and its metal complexes hold significant promise as novel therapeutic agents with multifaceted biological activities.

The intramolecular aggregation of phosphaphenanthrene groups and benzene-terminated effect within linear phosphonate oligomers effectively enhanced the flame retardancy and toughness of epoxy resin

To explore the potential of a flame retardant molecular structure that simultaneously enhances the flame retardancy and physical properties of epoxy resin (EP), benzene-terminated linear phosphonate oligomers Bz-DQPC-n were synthesized. Compared with the previously prepared linear bisphenol phosphonate oligomers DQPC-n, the benzene-terminated effect of Bz-DQPC-n molecules endows EP composites with better flame retardancy and toughness. In the vertical combustion (UL 94) test, Bz-DQPC-n/EP reached a V-0 rating. For the Bz-DQPC-2 molecule, the results revealed that under the same phosphorus contents, the limiting oxygen index (LOI) value of the Bz-DQPC-2/EP reached 38.2 %, which was higher than that of DQPC-2/EP. Furthermore, the peak heat release rate (pk-HRR) and total heat release rate (THR) of Bz-DQPC-2/EP were 677 kW/m2 and 83 MJ/m2. These values decreased by 54.7 % and 27.2 % in comparison to pure EP, respectively. In addition, the incorporation of Bz-DQPC-n can enhance the glass transition temperature (Tg) of EP composites. The flame retardant mechanism research demonstrated that Bz-DQPC-n molecules produced phosphorus-containing free radicals and aromatic compound fragments during gas-phase pyrolysis. These phosphorus-containing free radicals can interrupt or inhibit the combustion chain reaction process. A proportion of the aggregated phosphaphenanthrene groups decomposed to produce aromatic compounds that remained in the condensed phase, thereby enhancing the quality of the char layer. The investigation of the impact of the end-capping effect within Bz-DQPC-n molecules on the flame retardant behavior of EP composites offers a valuable reference for designing phosphaphenanthrene compounds with high flame retardant efficiency.

Elimination of hydrogen bonds in cellulose enables high-performance disordered carbon anode in sodium-ion batteries

Pre-oxidation remains an advantageous method to regulate the cross-linking structure of cellulose to prepare an increasingly disordered hard carbon applied in sodium-ion batteries. However, it is ambiguous how the introduction of oxygen affects the changes in the molecular structure of cellulose as well as the micro-structure of hard carbon. We herein systematically investigate the effect of air pre-oxidation on the crystallinity and cross-linking structure of cellulose macro-molecules by controlling the degree of oxidation. The findings indicate that the introduction of air can break the hydrogen bonding network of cellulose in advance and release a large number of reactive hydroxyl groups on the surface to be oxidized to form ether and ester cross-linking bonds. Ether bonds can transversely cross-link and extend the carbon layer and the bent carbon layers enclose a well-developed connective pore structure. Additionally, the breakage of oxygen-containing functional groups leads to the escape of large amounts of oxygen-containing gases to etch out more open pore structures with large pore sizes. Benefiting from these advantages, the prepared hard carbon possesses a specific capacity of 335 mAh·g‒1 and 89% of initial coulombic efficiency at 30 mA·g‒1 by pre-oxidating at 300°C for 12 h.

Proposition of In silico Pharmacophore Models for Malaria: A Review.

In the field of medicinal chemistry, the concept of pharmacophore refers to the specific region of a molecule that possesses essential structural and chemical characteristics for binding to a receptor and eliciting biological activity. Understanding the pharmacophore is crucial for drug research and development, as it allows the design of new drugs. Malaria, a widespread disease, is commonly treated with chloroquine and artemisinin, but the emergence of parasite resistance limits their effectiveness. This study aims to explore computer simulations to discover a specific pharmacophore for Malaria, providing new alternatives for its treatment. A literature review was conducted, encompassing articles proposing a pharmacophore for Malaria, gathered from the "Web of Science" database, with a focus on recent publications to ensure up-to-date analysis. The selected articles employed diverse methods, including ligand-based and structurebased approaches, integrating molecular structure and biological activity data to yield comprehensive analyses. Affinity evaluation between the proposed pharmacophore and the target receptor involved calculating free energy to quantify their interaction. Multiple linear regression was commonly utilized, though it is sensitive to multicollinearity issues. Another recurrent methodology was the use of the Schrödinger package, employing tools such as the Phase module and the OPLS force field for interaction analysis. Pharmacophore model proposition allows threedimensional representations guiding the synthesis and design of new biologically active compounds, offering a promising avenue for discovering therapeutic agents to combat Malaria.