Electronegative Groups Research Articles

Fluorinated porous covalent polymer nanofilm assembled sandwich separator: Lithiophilic sites engender uniform Li+ flux towards lithium metal battery

Lithium metal is renowned for its high theoretical specific capacity and extremely low reduction potential. Nevertheless, the repeated breaking/forming of the solid electrolyte interface and uncontrolled growth of lithium dendrites in lithium metal batteries significantly impede their commercial application. In this study, we propose a novel sandwich separator (F-BtTp@PP) composed of fluorinated porous covalent polymer nanofilms (F-BtTp-Nfilm) assembled using roll-to-roll technology. The F-BtTp@PP improves the pore distribution of PP, enhances its resistance to dendrite penetration, and promotes a uniform distribution of lithium ions flux. Furthermore, Fourier-transform infrared spectroscopy and density functional theory calculations confirm the energy affinity. Abundant lithophilic sites and strong electronegative groups effectively control the deposition behavior of lithium ions, resulting in a transfer number of 0.87. This mitigates effectively the occurrence of significant concentration gradients and localized hot-spots during cycles with high current density. The symmetrical cells of F-BtTp@PP Li|Li can maintain a stable cycling voltage of 52.2 mV for 5600 h under a current density of 20 mA cm−2 and capacity density of 10 mAh cm−2. This result robustly demonstrates the exceptional efficiency of F-BtTp@PP, which can be readily scaled up for protecting lithium metal anodes and provides valuable guidance for the design and industrial development of lithium metal batteries with modified separators.

Spherical g-C3N4@PDA nanocarrier for synergistic chemo-photothermal tumor therapy

In this paper, by wrapping the near-infrared (NIR) response polydopamine (PDA) as a nanocoating on the surface of spherical nano graphitic phase carbon nitride (g-C3N4), a multifunctional g-C3N4/PDA (CNP) nanocarrier platform was prepared. The π-conjugation system in PDA and the electronegative hydroxyl groups on the surface of CNP promote the creation of abundant active sites, which had a high drug loading rate of about 98.5 % for the electropositive GA. Due to the strong NIR reaction of CNP, the release of GA from CNP/GA can be greatly accelerated by the rising temperature, bonding disruption and charge transfer. Moreover, the photo-generated electron-hole pairs could be excited by the NIR effect of CNP, which promotes the production of ROS (·OH, ·O2– and 1O2) to induce apoptosis in HepG2 cells. Thus, the present spherical CNP nanocarrier with a combination of enzyme-mimic activity and NIR-responsive properties has a great potential for chemo-photothermal synergistic tumor therapy.

Culture-free detection of β-lactamase-Producing bacteria in urinary tract infections using a paper sensor

Developing simple, inexpensive, fast, sensitive, and specific probes for antibiotic-resistant bacteria is crucial for the management of urinary tract infections (UTIs). We here propose a paper-based sensor for the rapid detection of β-lactamase-producing bacteria in the urine samples of UTI patients. By conjugating a strongly electronegative group –N+(CH3)3 with the core structures of cephalosporin and carbapenem antibiotics, two visual probes were achieved to respectively target the extended-spectrum/AmpC β-lactamases (ESBL/AmpC) and carbapenemase, the two most prevalent factors causing antibiotic resistance. By integrating these probes into a portable paper sensor, we confirmed 10 and 8 cases out of 30 clinical urine samples as ESBL/AmpC- and carbapenemase-positive, respectively, demonstrating 100% clinical sensitivity and specificity. This paper sensor can be easily conducted on-site, without resorting to bacterial culture, providing a solution to the challenge of rapid detection of β-lactamase-producing bacteria, particularly in resource-limited settings.

Tribological Behavior of Sulfonated Polyether Ether Ketone with Three Different Chemical Structures under Water Lubrication.

With the development of the shipbuilding industry, it is necessary to improve tribological properties of polyether ether ketone (PEEK) as a water-lubricated bearing material. In this study, the sulfonated PEEK (SPEEK) with three distinct chemical structures was synthesized through direct sulfonated polymerization, and high fault tolerance and a controllable sulfonation degree ensured the batch stability. The tribological and mechanical properties of SPEEK with varying side groups (methyl and tert-butyl) and rigid segments (biphenyl) were compared after sintering in a vacuum furnace. Compared to the as-made PEEK, as the highly electronegative sulfonic acid group enhanced the hydration lubrication, the friction coefficient and wear rate of SPEEK were significantly reduced by 30% and 50% at least without affecting the mechanical properties. And lower steric hindrance and entanglement between molecular chains were proposed to be partially responsible for the lowest friction behavior of SPEEK with methyl side groups, making it a promising and competitive option for water-lubricated bearings.

Layer stacked polyimide with great built-in electronic field for fast lithium-ion storage based on strong p-p stacking effect

Polyimide has been regarded as a potential organic cathode for lithium-ion batteries (LIBs) due to its excellent solvent resistance, thermodynamic stability and flexibly programmable polymer structure. However, the poor conductivity, easy entanglement and agglomeration of PI chains lead to slow ion diffusion, poor electron transfer, and insufficient reaction, which make it difficult to effectively exert its theoretical capacity at high current density. Herein, a layer stacked polyimide cathode (NT-U) based on π-π stacking effect was successfully obtained. NT-U possesses a large molecular dipole moment that induced by the strong electronegative groups in PI and further enhanced by the π-π stacking structure, which contributes to the formation of a robust built-in electric field (BIEF). The strong BIEF in this highly crystalline PI plays a critical role in accelerating the charge transport dynamics and improving electrochemical performances of LIBs, as verified by in-situ XRD, ex-situ FTIR, ex-situ XPS, and ex-suit SEM, DFT calculations. These findings provide new insights into the construction of PIs cathode based on the mechanism of dipole and BIEF for fast and efficient energy storage.

Weak Electrostatic Force on K+ in Gel Polymer Electrolyte Realizes High Ion Transference Number for Quasi Solid-State Potassium Ion Batteries.

Quasi-solid-state potassium-ion batteries (SSPIBs) are of great potential for commercial use due to the abundant reserves and cost-effectiveness of resources, as well as high safety. Gel polymer electrolytes (GPEs) with high ionic conductivity and fast interfacial charge transport are necessary for SSPIBs. Here, the weak electrostatic force between K+ and electronegative functional groups in the ethoxylated trimethylolpropane triacrylate (ETPTA) polymer chains, which can promote fast migration of free K+, is revealed. To further enhance the interfacial reaction kinetics, a multilayered GPE by in situ growth of poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) on ETPTA (PVDF-HFP|ETPTA|PVDF-HFP) is constructed to improve the interface contact and provide sufficient K+ concentration in PVDF-HFP. A high ion transference number (0.92) and a superior ionic conductivity (5.15 × 10-3 S cm-1) are achieved. Consequently, the SSPIBs with both intercalation-type (PB) and conversion-type (PTCDA) cathodes show the best battery performance among all reported SSPIBs of the same cathode. These findings demonstrate that potassium-ion batteries have the potential to surpass Li/Na ion batteries in solid-state systems.

3D-QSAR and Molecular Dynamics Study of Isoxazole Derivatives to Identify the Structural Requirements for Farnesoid X Receptor (FXR) Agonists.

The farnesoid X receptor (FXR) has been recognized as a potential drug target for the treatment of non-alcoholic fatty liver disease (NAFLD). FXR agonists benefit NAFLD by modulating bile acid synthesis and transport, lipid metabolism, inflammation, and fibrosis pathways. However, there are still great challenges involved in developing safe and effective FXR agonists. To investigate the critical factors contributing to their activity on the FXR, 3D-QSAR molecular modeling was applied to a series of isoxazole derivatives, using comparative molecular field analysis (CoMFA (q2 = 0.664, r2 = 0.960, r2pred = 0.872)) and comparative molecular similarity indices analysis (CoMSIA (q2 = 0.706, r2 = 0.969, r2pred = 0.866)) models, which demonstrated strong predictive ability in our study. The contour maps generated from molecular modeling showed that the presence of hydrophobicity at the R2 group and electronegativity group at the R3 group in these compounds is crucial to their agonistic activity. A molecular dynamics (MD) simulation was carried out to further understand the binding modes and interactions between the FXR and its agonists in preclinical or clinical studies. The conformational motions of loops L: H1/H2 and L: H5/H6 in FXR-ligand binding domain (LBD) were crucial to the protein stability and agonistic activity of ligands. Hydrophobic interactions were formed between residues (such as LEU287, MET290, ALA291, HIS294, and VAL297) in helix H3 and ligands. In particular, our study found that residue ARG331 participated in salt bridges, and HIS447 participated in salt bridges and hydrogen bonds with ligands; these interactions were significant to protein-ligand binding. Eight new potent FXR agonists were designed according to our results, and their activities were predicted to be better than that of the first synthetic FXR agonist, GW4064.

Modifying Fluorescent Protein Chromophore to Detect Protamine and Application in Real Serum Samples

AbstractAs effective methods to accurately and rapidly detect protamine remains a major challenge, here we present a fluorescent protein chromophore‐based probe (IDL‐FP) utilizing twisted‐intramolecular charge transfer (TICT) to detect protamine. The introduction of an electron‐donor group 4‐dimethylaminobenzaldehyde extends the emission wavelength of IDL‐FP to the red region. The deprotection of t‐butyloxy carbonyl groups can then generate an electronegative carboxyl group, which promotes the binding to protamine via electrostatic attraction. Thus, IDL‐FP is sensitive and specific towards protamine and can serve as a highly selective detector for protamine with a detection limit as low as 8.87 ng/mL. As IDL‐FP exhibited good stability in physiological pH environment, we successfully apply IDL‐FP to detect spiked‐in protamine in human serum. In summary, probe IDL‐FP is a promising tool for the quantitative determination of protamine.

Chalcogen Atom Size: A Key Parameter in Modulating Carbonyl Compound Properties.

Exchanging oxygen in the functional group C=O (i. e., carbonyl) for the less electronegative Group 16 elements, sulfur or selenium, unexpectedly enhances the electronegativity of the C=X group in π-conjugated molecules and reduces the molecular π HOMO-LUMO energy gap. Quantum-chemical analyses revealed that the steric size of the chalcogen atom X is at the origin of this seemingly counterintuitive behavior. This tuning of the chemical properties of carbonyl compounds by varying the chalcogen atom size in the C=X bond can be applied in many fields of chemistry. This concept article delineates several useful applications in the fields of organocatalysis, supramolecular chemistry, and photo(electro)chemistry.

Novel Fluoroboric Acid Additive for Blend Membrane to be Used in PEM Fuel Cell, Characterization Studies, and Performance Test

This study focuses on developing an alternative membrane for PEMFC due to the disadvantages of using Nafion. Fluoroboric acid (FBA) was used as an additive material to SPEEK-PVA blend membranes at different weight ratios (1%, 5%, 7.5%, 10%, and 12.5%), and a synthesis procedure was carried out with the solution-casting. Thermal crosslinking was performed with all membranes. Utilizing FBA, with its highly electronegative fluorine groups, is a novel approach expected to enhance proton conductivity. The structural, morphological, and thermal properties of the synthesized membranes were determined by FTIR, XRD, SEM, TGA-DTG, and DSC. Water uptake capacity (WUC), swelling property, area change, dynamic mechanical analysis, ion exchange capacity (IEC), AC impedance analysis, hydrolytic stability, and oxidative stability analyses were performed for fuel cell applications. Although FBA does not have a crystal structure, the synergy it created with the SPEEK-PVA membrane increased the crystallinity of the membrane and, accordingly, glass transition temperature. SEM images of membranes at a ratio above 7.5% show that agglomerations occur in the structure and this is supported by other analyses. It was determined that the membrane composition with the highest WUC (16.44%), IEC (1.55 meq/g), and proton conductivity (0.57 S/cm) values contained 7.5% FBA from the characterization studies, and a single-cell performance test was actualized with this. 418 mA/cm2 current density and 250.8 mW/cm2 power density were obtained at 0.6 V cell potential, with the membrane containing 7.5% FBA. This study shows that the synthesized membrane, especially the FBA, is a promising option for PEMFC application.Graphical

More Electropositive is More Electronegative: Atom Size Determines C=X Group Electronegativity.

Opposite to what one might expect, we find that the C=X group can become effectively more, not less, electronegative when the Pauling electronegativity of atom X decreases down Groups 16, 15, and 14 of the Periodic Table. Our quantum-chemical analyses, show that, and why, this phenomenon is a direct consequence of the increasing size of atom X down a group. These findings can be applied to tuning and improving the hydrogen-bond donor strength of amides H2 NC(=X)R by increasingly withdrawing density from the NH2 group. A striking example is that H2 NC(=SiR2 )R is a stronger hydrogen-bond donor than H2 NC(=CR2 )R.

Epitaxial Nucleation of NaxFeFe(CN)6@rGO with Improved Lattice Regularity as Ultrahigh‐Rate Cathode for Sodium‐Ion Batteries

AbstractAlthough Prussian blue analogues are the promising candidate cathode materials for the Na‐ion batteries for the grid storage due to 3D open‐framework structure and large interstitial “A” sites, high content of defects in the crystals obtained in the conventional strategy severely impede Na+ migration, leading to an unsatisfactory power density. Here a novel epitaxial nucleation‐assisted controlled crystallization approach to eliminate the structural defects of NaFeHCF crystals is reported. Due to their limited lattice misfit of only 4.87% (< 5%) between the graphene and NaFeHCF as well as the electronegativity of the functional groups (─COOH, ─OH, ─CH(O)CH─), GO can act as the nucleation and subsequent epitaxial growth platform of NaFeHCF, which results in a unique one‐corner‐cut cubic nano‐crystals morphologies with much decreased contents of defects (0.08 per formula unit). This enhanced lattice regularity significantly enhanced the speedy diffusion of Na cations (by 5 times) in the nanocrystals, resulting in the unprecedented rate capability of 96.8 mAh g−1 at an ultra‐high rate of 9 A g−1 (39 s, 23228 W kg−1), which is far exceeding that of any previously reported PBA‐based cathodes to the knowledge, authenticating its superiority as a candidate for high‐power sodium‐ion batteries for the reliable grid energy storage.

Preparation of carbon-coated Fe2 O3 @Ti3 C2 Tx composites by mussel-like modifications as high-performance anodes for lithium-ion batteries.

Fe2 O3 with high theoretical capacity (1007 mA h g-1 ) and low cost is a potential anode material for lithium-ion batteries (LIBs), but its practical application is restricted by its low electrical conductivity and large volume changes during lithiation/delithiation. To solve these problems, Fe2 O3 @Ti3 C2 Tx composites were synthesized by a mussel-like modification method, which relies on the self-polymerization of dopamine under mild conditions. During polymerization, the electronegative group (-OH) on dopamine can easily coordinate with Fe3+ ions as well as form hydrogen bonds with the -OH terminal group on the surface of Ti3 C2 Tx , which induces a uniform distribution of Fe2 O3 on the Ti3 C2 Tx surface and mitigates self-accumulation of MXene nanosheets. In addition, the polydopamine-derived carbon layer protects Ti3 C2 Tx from oxidation during the hydrothermal process, which can further improve the electrical conductivity of the composites and buffer the volume expansion and particle agglomeration of Fe2 O3 . As a result, Fe2 O3 @Ti3 C2 Tx anodes exhibit ~100 % capacity retention with almost no capacity loss at 0.5 A g-1 after 250 cycles, and a stable capacity of 430 mA h g-1 at 2 A g-1 after 500 cycles. The unique structural design of this work provides new ideas for the development of MXene-based composites in energy storage applications.

Способы синтеза соединений фосфора R4PX, где Х  электроотрицательная группа

Based on the analysis of literature sources from the beginning of the 21st century to the present, various methods for obtaining phosphorus compounds of the general formula R4PX (X is an electronegative group) have been systematized and described. The present study is a continuation of classical research in the field of chemistry of organic phosphorus compounds in the Laboratory of Chemistry of Organoelement Compounds of South Ural State University. The prin-cipal attention is paid to synthesis methods for tetraorganylphosphonium derivatives based on radical redistribution reactions and substitution reactions, which are used to synthesize tetra-phenylphosphorus bromide and a series of alkyltriphenylphosphonium arenesulfonates, respec-tively. It has been shown that the single product of the interaction of triphenylphosphorus dibro-mide with pentaphenylphosphorus in a benzene solution (1 hour, 25 °C) is tetraphenylphosphoni-um bromide, isolated from the reaction mixture, yielding 92%. Tetraphenylphosphonium benzene-sulfonate has been obtained, yielding 90%, by a substitution reaction from tetraphenylphosphoni-um bromide and benzenesulfonic acid in water. Using a similar scheme, a series of alkyltri-phenylphosphonium arenesulfonates have been obtained with yields up to 92 %: [Ph3PC3H5-cyclo][OSO2Naft-1] (2), [Ph3PCH2СN][OSO2Mez)] (3), [Ph3PCH2СN][OSO2C6H3Сl2-2,5] ∙ ½MeOH (4), [Ph3PCH2OH][OSO2C6H3Сl2-2,5] ∙ H2O (5), [Ph3PEt][OSO2C6H3(NO2)2-2,4] (6), [Ph3P(СH2)2OH] [OSO2C6H3(NO2)2-2,4] (7), [Ph3P(С6H11-cyclo)] [OSO2C6H3(NO2)2-2,4] (8). The complex structures have been proved by IR spectroscopy and X-ray diffraction analysis (XRD). According to the XRD data, crystals of complexes 2–5 have ionic structure; they consist of tetraorganylphosphonium and arenesulfonate anions.

Improving the quantum yield of luminescence for three-coordinated gold(i) TADF emitters by exploiting inversion symmetry and using perhaloaryl ligands

New perhalophenyl gold(i)–tetraphosphino complexes are designed as highly efficient luminescent molecules. The electronegativity of the aryl groups and the symmetry of the molecules enable the formation of species with improved quantum yields at RT.

Strategy for Remediation of Polychlorinated Biphenyls-Contaminated Soil Through Redox Management Based on Electronegativity of the Contaminants.

Literature review reveals that Persistent Organic Pollutants (POPs), such as polychlorinated biphenyls (PCBs), are electron deficient compounds due to the presence of highly electronegative groups. Hence, they are more amenable to anaerobic biodegradation rather than oxidative metabolism. However, the studies on PCBs bioremediation are more inclined towards aerobic treatment. Besides, the past studies are mainly centered on screening and application of PCB-degrading microorganisms. In our opinion the degradative capacity is already present in the native microflora, and choice of electron donor is of paramount importance for faster reductive metabolism of PCBs. In this study, the use of methanol as electron donor with cow dung as the general microbial inoculum resulted in high specific rate of degradation (0.0542-0.0637 /day) for high-chlorinated biphenyls. The % removal of PCBs ranged between 67.7 and 71.7%. It may be the first study on the application of methanol as a cheap electron donor for PCBs biodegradation without bioaugmentation with specifically selected microorganisms.

Interface Engineering with Dynamics-Mechanics Coupling for Highly Reactive and Reversible Aqueous Zinc-Ion Batteries.

The practical application of AZIBs is hindered by problems such as dendrites and hydrogen evolution reactions caused by the thermodynamic instability of Zinc (Zn) metal. Modification of the Zn surface through interface engineering can effectively solve the above problems. Here, sulfonate-derivatized graphene-boronene nanosheets (G&B-S) composite interfacial layer is prepared to modulate the Zn plating/stripping and mitigates the side reactions with electrolyte through a simple and green electroplating method. Thanks to the electronegativity of the sulfonate groups, the G&B-S interface promotes a dendrite-free deposition behavior through a fast desolvation process and a uniform interfacial electric field mitigating the tip effect. Theoretical calculations and QCM-D experiments confirmed the fast dynamic mechanism and excellent mechanical properties of the G&B-S interfacial layer. By coupling the dynamics-mechanics action, the G&B-S@Zn symmetric battery is cycled for a long-term of 1900h at a high current density of 5mAcm-2 , with a low overpotential of ≈30mV. Furthermore, when coupled with the LMO cathode, the LMO//G&B-S@Zn cell also exhibits excellent performance, indicating the durability of the G&B-S@Zn anode. Accordingly, this novel multifunctional interfacial layer offers a promising approach to significantly enhance the electrochemical performance of AZIBs.

Regulating defect density of iron based metal–organic frameworks by defective ligands functionalization to enhance fenton-like activity and stability

Generating defect sites in iron based metal–organic frameworks (Fe-MOFs) by introducing defective ligands has recently emerged as an effective approach to optimize Fenton-like activity, but the structure–activity relationship between defective ligands and Fenton-like reaction is still not fully understood. Herein, a series of defective MIL-100(Fe), i.e., Dx-MIL-100(Fe), were constructed via introducing defective ligands with various functional groups including -N,–NO2,-Cl and –OH. It was observed that defect density and Fenton-like activity of DX-MIL-100(Fe) is positively correlated with the electronegativity of functional groups in defective ligands. With the increasing defect density, the stability and recyclability of DX-MIL-100(Fe) in Fenton-like reaction was not decreased, which is attributed to increasing coordination bond energy between defective ligands and Fe-O cluster. The high defect density results in the increase of electron density of Fe and rate of FeⅢ reduction. Therefore, DN-MIL-100(Fe) possessing highest defect density exhibited superior Fenton-like activity with the pseudo-first-order kinetic constant up to 0.089 min−1 for Bisphenol A degradation, which is 148.3 times than that of perfect MIL-100(Fe). Meanwhile, DN-MIL-100(Fe) showed excellent pH adaptability, anti-interference ability and cycle stability. This work unravels the role of functional groups in defective ligands on regulating defect density, Fenton-like activity and stability for the first time, which can provide a novel platform for precisely designing Fe-MOFs as promising Fenton-like catalyst.

Regulating the electronic microenvironment of adsorption sites in nanofiber for promoting In(III) capture performance

Enhancing adsorbent-adsorbate interactions via rational construction of adsorption sites is essential for the capture of the strategic metal indium. Herein, a nanofiber (PCA-Nanofiber) was successfully fabricated for In(III) ions recovery by introducing an electronegative fluorine-containing group to modulate the electronic structure of adsorption sites. Adsorption experiments exhibited that the maximum adsorption of PCA-Nanofiber for In(III) ions (116.3 mg/g) was 3.3 times higher than that of the pre-regulated nanofiber, exceeding most of the reported adsorbents. The PCA-Nanofiber maintained stable performance in five consecutive adsorption–desorption experiments and exhibited excellent selectivity. Furthermore, advanced spectroscopic characterization revealed that the adsorbed complex presented in a six-coordinated octahedral configuration, resembling an anti-triangular prism configuration centered on In(III) ions. The density functional theory demonstrates that the excellent adsorption performance benefits from the electronegative F atoms modulating the electronic microenvironment of the adsorption sites and optimizing the band-gap energy for charge migration, resulting in efficiently driven charge transfer. This work offers ideas for the rational design of adsorption sites in nanofiber from the perspective of regulation of electronic microenvironmental.

Adsorption performance of the functional COFs for removal of bisphenol A: Molecular dynamic simulations

The inherent structural features of the covalent organic frameworks (COFs) play a crucial role in determining their adsorption performances for bisphenol A (BPA). The computational methods were advantageous in unraveling intrinsic molecular properties about their performances. Herein, some COFs with different functional groups (–COOH, –NH2, –NO2 and –CF3) were designed to demonstrate the efficacy of the functional COFs for adsorbed BPA in gas phase and aqueous solution. The density functional theory (DFT) and Grand Canonical Monte Carlo (GCMC) methods were used to analyze the interaction energy between COFs and BPA, structure properties, and adsorption performances etc.. The results indicated that the addition of strong electronegative functional groups in COFs increased these COFs’ isosteric heat of adsorption (Qst) (TpBD-(COOH)2 > TpBD-(CF3)2 > TpBD-(NH2)2 > TpBD-(NO2)2 > TpBD) for gas phase BPA, but their introduction also reduced the pore size of COFs (TpBD > TpBD-(COOH)2 > TpBD-(NH2)2 > TpBD-(CF3)2 > TpBD-(NO2)2). However, these functional COFs demonstrated the stronger the adsorption capacity for gas phase BPA (At 298 K and 1 bar, the BPA uptake of TpBD-(COOH)2, TpBD-(NH2)2, TpBD, TpBD-(NO2)2 and TpBD-(CF3)2 was 242.52, 232.43, 219.31, 206.64 and 197.73 mg/g, respectively.). The amount of BPA adsorbed by functional COFs was the result of the synergistic effect of the electronegativity of functional groups and the pore size. Molecular dynamic (MD) simulation performed the same phenomenon for BPA in aqueous solution. In addition, the higher temperature will decrease the adsorption amount of BPA by COF, but increase its desorption ability.