Strong Hydrogen-bonding Interactions Research Articles

Tunable protic ionic liquid catalysts for the efficient one-step synthesis of isosorbide-based polycarbonates

Using CO2-derived dimethyl carbonate (DMC) instead of diphenyl carbonate (DPC) as a carbonyl source for synthesizing bio-based polycarbonates is a green and cost-effective route. However, the synthesis of high-performance polycarbonates via the DMC route remains challenging due to the poor reactivity and selectivity of DMC compared to DPC. Herein, we designed a series of highly active protic ionic liquid (PIL) catalysts for the synthesis of poly(isosorbide carbonate) (PIC) from DMC with ISB. The influences of the structures of anion and cation on the catalytic activity of PILs were systematically studied. Compared with the reported aprotic IL catalysts, the unique reactive hydrogen of the cation in PILs could form a strong hydrogen bond interaction with the carbonyl group of DMC, resulting in higher reactivity of the carbonyl carbon of DMC. Moreover, the nucleophilicity of the anion could be easily tuned by adjusting the pKa value, which effectively realized the balance of the reactivity difference between exo-OH and endo-OH in ISB. Among them, [DBUH][Im] showed the highest catalytic activity, and the weight-average molecular weight (Mw) and glass transition temperature of PIC reached 55,700 g/mol and 160 °C, respectively. Combined with NMR analyses and DFT calculations, the mechanism that exhibited the synergetic catalytic effect of anion-cation for the polymerization of DMC and ISB was presented.

Encapsulating phase change materials into melamine formaldehyde sponge assembled with polypyrrole modified halloysite nanotube for effective solar-thermal energy storage and solar-thermal-electric conversion

Exploiting inexpensive composite phase change materials (PCMs) with comprehensive characteristics of high encapsulation efficiency, good leakage resistance, strong flexibility, high heat conductivity, and powerful light absorption is considerably imperative for their solar-thermal and solar-thermal-electric conversion. Herein, polypyrrole (PPy) modified halloysite (HNT/PPy) was assembled into the pores of melamine formaldehyde (MF) sponge to construct hierarchical porous structure (MHP), in which PPy serves as light absorber and heat conducting agent to consolidate the light absorption and thermal conductivity, while the interwoven HNT in MF not only acts as carrier to provide sufficient space for guaranteeing more PCMs’ encapsulation, but also dramatically narrows MF’s pore size and prevents PCMs’ leakage. As expected, the MHP can encapsulate as high as 95 wt% of polyethylene glycol (PEG) with extremely high latent heat of 177.8 J g−1 (PEG@MHP). The rich hydroxyl groups on PEG, PVA and HNT form strong hydrogen bond interaction, effectively improving the leakage-proof performance of PEG@MHP. Especially, PEG@MHP with 82 wt% encapsulation ratio (PEG@MHP-82) demonstrates unexceptionable leakage resistance (negligible leakage at 100 °C), strong light absorption (97 %), good photothermal conversion efficiency (90.36 %), and high thermal conductivity (0.235 W m−1 K−1). Except that, the solar-thermal-electric (STE) conversion system assembled with PEG@MHP-82 enables efficient voltage and current outputs of 587 mV and 83.3 mA respectively under 3 kW m−2 with heat dissipation in water. Encouragingly, the voltage output still achieves 154.7 mV under actual outdoor illumination (0.984 kW m−2). This work provides a simple method to efficiently encapsulate PCMs for realizing high-efficiency solar-thermal and solar-thermal-electric conversion.

Investigating the self-assembly of pH-sensitive switchable diamine surfactant using sum frequency generation spectroscopy and molecular dynamics simulations.

The responses of the N-alkyl diamine groups to variations in pH affect their conformations and surface activities, making them relevant to applications relying on interfacial interactions, such as controlled emulsification and mineral flotation. An in-depth understanding of interfacial self-assembly is crucial. Herein, a molecular-level study was performed to investigate the adsorption and self-assembly of N-dodecylpropane-1,3-diamine (DPDA) at the air-water (A/W) interface using sum frequency generation (SFG) spectroscopy and molecular dynamics (MD) simulations. The SFG spectra of DPDA, acquired under three pH conditions, suggest that the protonation of the DPDA diamine group influences the alkyl chain arrangement at a varying degree at the A/W interface. Analysis of the di-cationic DPDA SFG spectrum at a low pH showed fewer gauche defects at low concentration, as indicated by the relatively higher intensity ratio (ICH3SS/ICH2SS) of 18.1 ± 0.6. The density profiles from MD simulations at different surface areas per molecule and pH conditions, showing varying degrees of packing, support the observation of gauche defects in SFG. With MD simulation, the radial distribution factor for di-cationic species has the highest probability of forming hydrogen bonds compared to mono-cationic and non-ionic species. These g(r) probability results conform with observations obtained from SFG spectroscopy, where we observed a strong hydrogen bond interaction at low pH conditions with di-cationic species, forming tetrahedrally arranged water molecules at the A/W interface. Overall, comprehensive insights will facilitate the visualization of alkyl diamines and their potential derivatives at the A/W interface, enabling a better understanding of their behavior across various applications.

Selective adsorption behaviors and mechanisms of benzyl quaternary ammonium salt on quartz and gypsum: A combined experimental and theoretical study

Benzyl quaternary ammonium salt is an effective collector of quartz from gypsum. To investigate the selective collection mechanism of tetradecyl dimethyl benzyl ammonium chloride (TDBAC) for quartz from a microscopic view, the adsorption experiments, first-principles calculations based on density functional theory (DFT), and molecular dynamics (MD) simulation were performed in this work. The adsorption experiment results show that the adsorption capacity of TDBAC on the quartz surface was 1.6 × 10−6 mol/m2, much larger than that on the gypsum surface (1.0 × 10−7 mol/m2). The interaction energy of TDBAC with quartz surface was −20202.98 kJ/mol, much smaller than that with gypsum surface (-78.37 kJ/mol). DFT calculation results indicate that the quartz surface was more likely to interact with TDBAC through electrostatic attraction since the average negative charge and exposure oxygen density of the quartz surface were both greater than those of the gypsum surface. After the adsorption of TDBAC, there were hydrogen bonds formed between the hydrogen atoms in TDBAC and the oxygen atoms on the quartz surface. This work confirmed that the highly selective adsorption of TDBAC on quartz surface was attributed to the strong electrostatic attraction and hydrogen-bond interaction.

Supramolecular Polymer Additives as Repairable Reinforcements for Dynamic Covalent Networks.

Employing rigid (in)organic materials as reinforcement for dynamic covalent networks (DCNs) is an effective approach to develop high-performance materials. Yet, recycling of these materials after failure often necessitates inefficient chemical reprocessing or inevitably alters their performance due to unrepairable inert components. Here, a non-covalent reinforcement strategy is presented by introducing a supramolecular additive to a DCN that can reversibly depolymerize and reform on demand, therefore acting as an adaptive and repairable reinforcement. The strong hydrogen-bonding interactions in the supramolecular polymer of triazine-1,3,5-tribenzenecarboxamide (S-T) strengthen the DCN at room temperature, while its non-covalent nature allows for easy one-pot reprocessing at high temperatures. Depending on wether S-T is covalently bond to the DCN or not, it can play either the role of compatibilizer or filler, providing a synthetic tool to control the relaxation dynamics, reprocessability and mechanical properties. Moreover, the S-T reinforcement can be chemically recovered with high yield and purity, showcasing the recyclability of the composite. This conceptually novel supramolecular reinforcement strategy with temperature-controlled dynamics highlights the potential of supramolecular polymer additives to replace conventional unrepairable reinforcements.

Sieving-type Electric Double Layer with Hydrogen Bond Interlocking to Stable Zinc Metal Anode.

The stability of aqueous zinc metal batteries is significantly affected by side reactions and dendrite growth on the anode interface, which primarily originate from water and anions. Herein, we introduce a multi H-bond site additive, 2, 2'-Sulfonyldiethanol (SDE), into an aqueous electrolyte to construct a sieving-type electric double layer (EDL) by hydrogen bond interlock in order to address these issues. On the one hand, SDE replaces H2O and SO4 2- anions that are adsorbed on the zinc anode surface, expelling H2O/SO4 2- from the EDL and thereby reducing the content of H2O/SO4 2- at the interface. On the other hand, when Zn2+ are de-solvated at the interface during the plating, the strong hydrogen bond interaction between SDE and H2O/SO4 2- can trap H2O/SO4 2- from the EDL, further decreasing their content at the interface. This effectively sieves them out of the zinc anode interface and inhibits the side reactions. Moreover, the unique characteristics of trapped SO4 2- anions can restrict their diffusion, thereby enhancing the transference number of Zn2+ and promoting dendrite-free deposition and growth of Zn. Consequently, utilizing an SDE/ZnSO4 electrolyte enables excellent cycling stability in Zn//Zn symmetrical cells and Zn//MnO2 full cells with lifespans exceeding 3500 h and 2500 cycles respectively.

Sieving‐type Electric Double Layer with Hydrogen Bond Interlocking to Stable Zinc Metal Anode

AbstractThe stability of aqueous zinc metal batteries is significantly affected by side reactions and dendrite growth on the anode interface, which primarily originate from water and anions. Herein, we introduce a multi H‐bond site additive, 2, 2′‐Sulfonyldiethanol (SDE), into an aqueous electrolyte to construct a sieving‐type electric double layer (EDL) by hydrogen bond interlock in order to address these issues. On the one hand, SDE replaces H2O and SO42− anions that are adsorbed on the zinc anode surface, expelling H2O/SO42− from the EDL and thereby reducing the content of H2O/SO42− at the interface. On the other hand, when Zn2+ are de‐solvated at the interface during the plating, the strong hydrogen bond interaction between SDE and H2O/SO42− can trap H2O/SO42− from the EDL, further decreasing their content at the interface. This effectively sieves them out of the zinc anode interface and inhibits the side reactions. Moreover, the unique characteristics of trapped SO42− anions can restrict their diffusion, thereby enhancing the transference number of Zn2+ and promoting dendrite‐free deposition and growth of Zn. Consequently, utilizing an SDE/ZnSO4 electrolyte enables excellent cycling stability in Zn//Zn symmetrical cells and Zn//MnO2 full cells with lifespans exceeding 3500 h and 2500 cycles respectively.

Adipogenic Effects of Cresyl Diphenyl Phosphate (Triphenyl Phosphate Alternative) through Peroxisome Proliferator-Activated Receptor Gamma Pathway: A Comprehensive Study Integrating In Vitro, In Vivo, and In Silico from Molecule to Health Risk.

Cresyl diphenyl phosphate (CDP), a novel organophosphate ester (OPE), has been detected in various environmental and human samples. However, there is very limited knowledge regarding its toxicity, mechanisms of action, and potential health risks. Using new alternative methods (NAMs), across the molecular interactions, signaling pathways, cell functions, animal effects, and population risks, we investigated the potential adipogenic effects and associated risks of CDP and legacy OPE triphenyl phosphate (TPHP) by acting on peroxisome proliferator-activated receptor gamma (PPARγ). Among the 19 screened OPEs, CDP bound to PPARγ with the highest binding potency, followed by TPHP. CDP activated PPARγ through fitting into the binding pocket with strong hydrophobicity and hydrogen bond interactions; CDP exhibited higher potency compared to TPHP. In 3T3-L1 cells, CDP enhanced the PPARγ-mediated adipogenesis activity, exhibiting greater potency than TPHP. The intracellular concentration and receptor-bound concentrations (RBC) of CDP were also higher than those of TPHP in both HEK293 cells and 3T3-L1 cells. In mice, exposure to CDP activated the PPARγ-mediated adipogenic pathway, leading to an increased white adipose tissue weight gain. Overall, CDP could bind to and activate PPARγ, thereby promoting preadipocyte differentiation and the development of white adipose tissue. Its potential obesogenic risks should be of high concern.

N,N′-Dibenzylethylenediammonium dichloride

The isolation and crystalline structure of N,N′-dibenzylethylenediammonium dichloride, C16H22N2 2+·2Cl−, is reported. This was obtained as an unintended product of an attempted Curtius rearrangement that involved benzylamine as one of the reagents and 1,2-dichloroethane as the solvent. Part of a series of reactions of a course-based undergraduate research experience (CURE), this was not the intended reaction outcome. The goal of the course was to engage students as active participants in a laboratory experience which applies the foundational techniques of a synthetic organic laboratory, using the Curtius rearrangement as a tool for the assembly of medicinally significant scaffolds. The isolation of the title compound, N,N′-dibenzylethylenediammonium dichloride, the result of the 1,2-dichloroethane solvent outcompeting the Curtius isocyanate intermediate in the reaction with the nucleophilic amine, confirms the importance of conducting research at the undergraduate level where the outcome is not predetermined. The solid-state structure of N,N′-dibenzylethylenediammonium dichloride was found to feature an all-trans methylene-ammonium backbone. Strong N—H...Cl hydrogen bonds and C—H...Cl interactions lead to a layered structure with pseudo-translational symmetry emulating a C-centered setting. Different phenyl torsion angles at each end of the molecule enable a more stable packing by allowing stronger hydrogen-bonding interactions, leading to a more ordered but lower symmetry and modulated structure in P21/n.

Simple synthesis of monocyclic pyrimidine-based energetic molecule with “amino–nitro–hydrazino” arrangement

With the constant development of energetic materials, numerous explosive molecules have been synthesized, some of which feature competitive performances. However, energetic materials are directly oriented to application requirements. Therefore, more emphasis is gradually placed on route simplification and cost reduction while designing novel energetic molecules. In this work, monocyclic energetic compound 2,4-diamino-6-hydrazineyl-5-nitropyrimidine (3) was successfully obtained. This compound exhibits an alternating “amino–nitro–hydrazino” arrangement, featuring strong intramolecular hydrogen-bonding interaction. With cheap raw material, the whole reaction comprised only two steps, and exhibited simple post processing, only filtration. This novel energetic molecule possesses excellent mechanical security (IS > 40 J, FS > 360 N), acceptable thermal stability (Td = 225 °C), and good detonation parameters (Dv = 8470 m/s, P = 24.9 GPa), indicating that compound 3 may act as a candidate of insensitive explosives.

Lignin-modified cellulose nanofibers hydrogel under adjustable binary solvent systems with excellent adhesion, self-healing and anti-freeze properties

Hydrogels with remarkable flexibility have gained popularity as materials for current research. However, the unfavorable properties of short-term adhesion, susceptibility to damage, and freezing in low-temperature presented by conventional hydrogels have become bottlenecks for further applications. In this work, an anti-freezing hydrogel with excellent mechanical, adhesion, and self-healing properties were developed by constructing a persistent semiquinone/quinone-catechol redox equilibrium environment. The introduction of lignin-modified cellulose nanofibers (LCNFs) significantly improved the overall mechanical properties of the material, driven by strong hydrogen bond interactions. This enhancement was evident in the tensile properties (97.74 ± 1.72 kPa, 783 %) and compression properties (> 90 %). Within the internal network of the gel, the synergistic action of lignin and ammonium persulfate resulted in the production of catechol, which imparted the gel with excellent adhesion properties (28.26 ± 2.13 KPa) and broad adhesion applicability. In addition, the incorporation of ethylene glycol (EG) positively contributed to the strengthening of the gel while endowed with tunable anti-freezing properties. Given the exceptional advantages of the prepared hydrogels, they were used to assemble flexible strain sensors with outstanding sensitivity for monitoring human motions.

Design, synthesis, and evaluation of chalcone derivatives as xanthine oxidase inhibitors

Xanthine oxidase (XO) is an important enzyme that catalyzes the oxidation of hypoxanthine to xanthine and xanthine to uric acid in the catabolism of purines in humans. This makes XO a well-recognized target in alleviating hyperuricemia. The present study adapted a structure-based drug discovery approach to develop potent and low-toxicity XO inhibitors with the chalcone skeleton. We introduced a carboxyl group and a hydroxyl group to the B ring and modified the A ring. 35 chalcone derivatives were designed and synthesized. All the 35 derivatives exhibited higher XO inhibition activities (IC50 = 0.064–0.559 μM) compared with allopurinol (IC50 = 2.588 μM). Their high affinity was attributed to strong hydrogen bond interactions formed between the introduced carboxyl and hydroxyl groups with key amino acid residues in XO. SAR analysis disclosed that carboxyl, hydroxyl, ethyl (12c), methylamino (12h), dimethylamino (12i), indolin (13k), and indol (13l) groups played important roles in improving the whole molecules’ inhibition potency against XO. ADME predictions and cytotoxicity assays suggested their pharmacokinetic characteristics and biocompatibility were desirable. Additionally, 12c exhibited a significant hypouricemic effect on potassium oxonate-induced hyperuricemia rats after orally administrated at a dose range of 10–40 mg/kg, representing a promising anti-hyperuricemia potential for further optimization and development.

Protonation-induced tautomerization lowers the activation barriers for N-glycosidic bond cleavage of thymidine and 5-methyluridine

Synergistic infrared multiple photon dissociation (IRMPD) action spectroscopy experiments and electronic structure calculations revealed that both 2,4-dihydroxy tautomers and O2 protonated conformers of protonated thymidine, [dThd+H]+, and protonated 5-methyluridine, [Thd+H]+ coexist in the gas phase with the 2,4-dihydroxy tautomers dominating the population. In the current study, the kinetic energy dependence of the collision-induced dissociation behavior of [dThd+H]+ and [Thd+H]+ are examined in a guided ion beam tandem mass spectrometer. The primary dissociation pathways observed involve N-glycosidic bond cleavage leading to competitive elimination of either protonated or neutral thymine. The potential energy surfaces (PESs) for these N-glycosidic bond cleavage pathways are mapped via electronic structure calculations for the mixture of 2,4-dihydroxy tautomers and O2 protonated conformers of [dThd+H]+ and [Thd+H]+ populated in the IRMPD experiments. The activation energies and heats of reaction predicted for N-glycosidic bond cleavage at the B3LYP and MP2(full) levels of theory are compared to the measured values. The agreement between experiment and theory indicates that B3LYP provides better estimates of the energetics of the species along the PESs for N-glycosidic bond cleavage of [dThd+H]+ and [Thd+H]+ than MP2, and that the 2,4-dihydroxy tautomers, which are stabilized by strong hydrogen-bonding interactions, control the threshold dissociation behavior of [dThd+H]+ and [Thd+H]+.

Amino acid – Squaramide conjugates as anion binding receptors

Squaramides have garnered significant attention as anion binding motifs and have become a popular supramolecular synthon owing to their unique structural features and propensity to form strong hydrogen bond interactions particularly with anionic species. However, their conjugation to biomaterials to form biomimetic receptors remains underexplored even though such species would combine the biocompatibility of amino acids with the strong hydrogen bonding propensity of squaramides and may prove useful across broad applications in the chemical and biological sciences. In this study, we present the design and synthesis of a series of amino acid – squaramide conjugates (AASqs) 1 – 5, as well as studying their anion recognition properties. 1–5 were prepared using facile synthetic methods and their anion binding properties were investigated via 1H NMR titrations with a range of anions in 0.5 % H2O in DMSO‑d6. Our findings constitute a cautionary tale, where it was shown that the presence of the C-terminal carboxylic acid of the amino acids complicate the binding behaviour of the receptors towards anions. We show that the C-terminal carboxylates compete with other anionic species for the squaramide binding site leading to complex binding equilibria in solution. However, upon esterification of the C-termini to afford compound 5, a simplification of the binding profile was observed and was easily fitted to a 1:1 (Receptor:Anion) binding stoichiometry. This work sheds light on the potential of AASqs as anion binding receptors whilst underlining the influence of the C-terminus on anion recognition. It also provides a direct solution to mitigate the complex binding behaviour of 1–4 through esterification and will prove useful in the design of more complex squaramide bioconjugates.

Extraction of Pyrrole from Its Mixture with n-Hexadecane Using Protic Ionic Liquids.

The removal of nitrogen compounds from fuel via the conventional method, which is hydrodenitrogenation, is costly and involves catalysts and energy-intensive conditions (600 K and 300 atm). Recently, ionic liquids (ILs) have emerged as a promising alternative solvent for the denitrogenation of fuel oil. However, certain ILs are expensive and challenging to synthesize, prompting the exploration of protic ionic liquid (PIL) substitutes, which offer similar advantages to ILs. This study utilized the conductor-like screening model for real solvents (COSMO-RS) to predict the phase equilibria for three PILs-triethylammonium p-toluenesulfonate (TEA-TSA), triethylammonium salicylate (TEA-SA) and triethylammonium benzoate (TEA-BZ)-which were subsequently validated through experimental investigations. Liquid-liquid extraction experiments were conducted at 298 K and 1 atm, with pyrrole (serving as the model nitrogen compound) concentrations in n-hexadecane (representing the model fuel) ranging from 10 to 50 wt%. Additionally, the NRTL model effectively correlated the experimental tie lines. The obtained data indicated that TEA-TSA exhibited superior selectivity and distribution ratio compared to TEA-SA and TEA-BZ. All the ternary systems tested displayed positive slopes, suggesting a higher affinity of nitrogen compounds for the PIL. Supporting this observation, interaction energy (ΔE) and excess enthalpy (HE) were employed. The predicted outcomes revealed that TEA-TSA had high ΔE, and all PILs exhibited negative values of HE. The HE calculation underscored the significance of strong hydrogen bond interactions between pyrrole and the PIL for successful extraction.

In-situ assembly of polypyrrole onto heterocyclic aramid for high-strength, ultratough, durable, and multifunctional films

High-strength, ultratough, multifunctional polymer-based electromagnetic interference (EMI) shielding nanocomposite films have colossal application potential in artificial intelligence, 5G communications, and flexible electronics. In this work, a large-scale, high-strength, and ultratough heterocyclic aramid@polypyrrole (HA@PPy) composite film is developed via the in-situ loading of PPy onto the HA template. The synthesized films achieve remarkable mechanical properties and high electronic conductivity by using the template effect of HA to guide the assembly of conductive polymers. When the content of PPy is 45 wt%, the HA@PPy (HP45) film possesses excellent tensile strength (240.3 MPa), significant elongation at break (25.9 %), outstanding toughness (53.1 MJ m−3), and exceptional folding durability owing to strong hydrogen bond interaction between PPy and HA. Furthermore, thanks to the highly connected conductive paths formed by PPy, the HP45 film exhibits satisfactory EMI shielding effectiveness (EMI SE) of 45.5 dB and specific EMI SE of 14691.6 dB cm2 g−1 at an ultra-thin thickness (26.3 μm). The HP45 film also demonstrates excellent electromagnetic protection, electro-/photothermal deicing, thermal therapy, and flame retardancy applications. Therefore, high-performance and multifunctional HA@PPy films have substantial potential for widespread application in EMI shielding and thermal management.

Spectroscopic, solvent interactions, topological analysis, docking evaluation with biological studies on 1,3,3-trimethyl-2-oxybicyclo[2.2.2] octane by anti-cancer proteins

In the current study the title molecules have been shown the anticancer properties of few cancers cell line and biological activity. Electron transition, solute solvent, experimental and computational exploring on the natural bio-molecular structure 1,3,3-tri methyl-2-oxybicyclo[2.2.2] octane stimulated by B3LYP/6–311++G (d,p) set. The 1TOBO molecular structure has identified from GC–MS study by extract of Zingiber Officianale Roscoe. The optimized parameters are correlated with XRD data and NBO expressed the delocalization of charge due to intermolecular interactions and their stronger stabilization E(2) = 4.01 Kcal/mol. The experimental spectral data recorded in the range 400–4000 cm−1 of 1TOBO and strong correlated with computational spectral have been estimated. The UV–vis spectra of corresponding gas phase and solvent-liquid estimated by TD-SCT process well agreement with reported spectra. 1H and 13C NMR spectrum have been capturing the chemical shifts of 1TOBO interpreted by Gauge Independent Atomic Orbital (GIAO) approach with carbinol solvent. The HOMO-LUMO values, Mulliken charges and MEP surface were used to predict the regioselectivity reaction in the region of electrophilic and nucleophilic attack. The topological analysis of LOL and ELF surfaces have been estimated and RDG-NCI map exhibits the van der Walls, steric effect and strong hydrogen bond interaction within the molecules. The Electron-hole distribution analysis revealed the electron transition of three excited states. Furthermore, the quantitative analysis of drug likeness and ADMET were studied. The molecular docking determines the lowest binding impact on the 1TOBO against cancer proteins 7QTZ, 1OXR have been estimated by Auto dock software.

Unraveling the Roles of Ionic Size and Hydrogen Bonding in Electric Field-Driven Ion Emission from Hydroxylamine Nitrate-Based Ionic Liquids.

Ionic size and hydrogen bonding (HB) may play significant roles in controlling ion emission from HAN (hydroxylamine nitrate)-based ionic liquids (ILs) but have received little attention. In this paper, the ion emission behavior and mechanism in an external electric field are meticulously investigated using the molecular dynamics (MD) method and density functional theory. We find that the higher the proportion of ionic HAN in the blend of ILs, the longer the delay time of the ion start-up emission. In the positive mode, cations can evaporate directly from the surface of the studied ILs and manifest exclusively as the [EMIM]+ monomers within the simulation time scale, whereas in the negative mode, a variety of complicated anion clusters are emitted. As a result, the average charge-to-mass ratio of the positively charged species remarkably exceeds that of the negatively charged species. This large difference is attributed to the relatively larger size of the [EMIM]+ ion and the absence of substantial HB interactions between the [EMIM]+ ion and any other monomer, leading to diminished binding energies. Conversely, the strong HB interactions, primarily constituted by N-H--O and O-H--O hydrogen bonds, are clearly found in the [EtSO4]--based and HAN-based clusters. In addition, the [NO3]- and [EtSO4]- ions tend to combine with the small-sized [HA]+ ions to form large anion clusters rather than with the [EMIM]+ ions. The energy decomposition results further elucidate that the orbital interaction plays a pivotal role in the [NO3]- and [EtSO4]--based clusters. The findings clearly elucidate the experimental phenomena observed in previous studies and have implications for the formulation of multimode IL propellants.

Guanidinium and spermidinium decavanadates: as small biomimetic models to understand non-covalent interactions between decavanadate and arginine and lysine side chains in proteins

During the last three decades, numerous investigations have been conducted on polyoxidovanadates to treat several illnesses and inhibit enzymes. Numerous decavanadate compounds have been proposed as potential therapies for Diabetes mellitus, Cancer, and Alzheimer’s disease. Only six relevant functional proteins interacting with decavanadate, V10, have been deposited in the PDB. These are acid phosphatase, tyrosine kinase, two ecto-nucleoside triphosphate diphosphohydrolases (NTPDases), the human transient receptor potential cation channel (TRPM4), and the human cell cycle protein CksHs1. The interaction sites in these proteins mainly consist of Arginine and Lysine, side chains binding to the decavanadate anion. To get further knowledge regarding non-covalent interactions of decavanadate in protein environments, guanidinium and spermidinium decavanadates were synthesized, crystallized, and subjected to analysis utilizing various techniques, including FTIR, Raman, 51V-NMR, TGA, and X-ray diffraction. The DFT calculations were employed to calculate the interaction energy between the decavanadate anion and the organic counterions. Furthermore, the Quantum Theory of Atoms in Molecules (QTAIM) and Non-covalent Interaction-Reduced Density Gradient (NCI-RDG) analyses were conducted to understand the non-covalent interactions present in these adducts. Decavanadate can engage in electrostatic forces, van der Waals, and hydrogen bond interactions with guanidinium and spermidinium, as shown by their respective interaction energies. Both compounds were highly stabilized by strong hydrogen bond interactions N−H···O and weak non-covalent interactions C−H···O. In addition, the interactions between guanidinium and spermidinium cations and decavanadate anion form several stable rings. This study provides new information on non-covalent intermolecular interactions between decavanadate and small biomimetic models of arginine and lysine lateral chains in protein environments.

Citrus-derived flavanones as neuraminidase inhibitors: In vitro and in silico study

Neuraminidase (NA) has been well-studied as a therapeutic target for Influenza. However, resistance to the influenza virus has been observed recently. Out of special interest in the utilization of dietary antivirals from citrus, in vitro inhibition activity against NA and in silico studies including molecular docking, molecular dynamic simulation, and a predictive ADMET study, were performed on five citrus-derived flavanones. Encouragingly, citrus-derived flavanones displayed comparable or even more potent in vitro inhibitory activity than oseltamivir carboxylate against NA. Orange peel extract exhibited higher activity than hesperidin. Among the tested compounds, neohesperidin, forming strong hydrogen-bonding interactions with key arginine residues, exhibited the most effective inhibitory activity against NAs from C. perfringens, consistent with the results of molecular dynamics simulations. Although the molecular docking results were inconsistent with the in vitro activity, the binding energy was identical against the wild-type and mutant, suggesting a lower likelihood of developing drug resistance. Moreover, predictive ADMET studies showed favorable pharmacokinetic properties for the tested compounds. Overall, citrus fruit peel emerges as a promising dietary supplement for prevention and treatment of influenza. These findings elucidate the impact of flavanones on NA activity, and the analysis of their binding modes provides valuable insights into the mechanism of NA inhibition.