Lone Pair Research Articles

Electron Dynamics in Alkane C-H Activation Mediated by Transition Metal Complexes.

Alkanes, ideal raw materials for industrial chemical production, typically exhibit limited reactivity due to their robust and weakly polarized C-H bonds. The challenge lies in selectively activating these C-H bonds under mild conditions. To address this challenge, various C-H activation mechanisms have been developed. Yet, classifying these mechanisms depends on the overall stoichiometry, which can be ambiguous and sometimes problematic. In this study, we utilized density functional theory calculations combined with intrinsic bond orbital (IBO) analysis to examine electron flow in the four primary alkane C-H activation mechanisms: oxidative addition, σ-bond metathesis, 1,2-addition, and electrophilic activation. Methane was selected as the representative alkane molecule to undergo C-H heterolytic cleavage in these reactions. Across all mechanisms studied, we find that the CH3 moiety in methane consistently uses an electron pair from the cleaved C-H bond to form a σ-bond with the metal. Yet, the electron pair that accepts the proton differs with each mechanism: in oxidative addition, it is derived from the d-orbitals; in σ-bond metathesis, it resulted from the metal-ligand σ-bonds; in 1,2-addition, it arose from the π-orbital of the metal-ligand multiple bonds; and in electrophilic activation, it came from the lone pairs on ligands. This detailed analysis not only provides a clear visual understanding of these reactions but also showcases the ability of the IBO method to differentiate between mechanisms. The electron flow discerned from IBO analysis is further corroborated by results from absolutely localized molecular orbital energy decomposition analysis, which also helps to quantify the two predominant interactions in each process. Our findings offer profound insights into the electron dynamics at play in alkane C-H activation, enhancing our understanding of these critical reactions.

Sb2O2SeO3 and Sb2O(SeO3)2: Two-Layered Antimony(III) Selenites with Enhanced Birefringence.

Two antimony selenites, Sb2O2SeO3 and Sb2O(SeO3)2, were synthesized by simultaneously incorporating stereochemically active lone pair electrons containing SeO32- and Sb3+. These compounds are structured with [SbOx] polyhedra and [SeO3] units within a two-dimensional framework. Both of them exhibit cutoffs at 300 and 330 nm within the ultraviolet (UV) range and demonstrate significant birefringence, with indices of 0.069 and 0.126 at 546 nm, respectively. These properties highlight their potential as UV birefringent materials. Structural analyses and theoretical calculations reveal that their exceptional birefringence results from the synergistic interactions between SeO32- anions and Sb3+ cations.

LnSb2O4Br (Ln=Nd and Er) and Sb4O5Br2: Lanthanoid‐Bearing and ‐Free Antimony(III) Oxide Bromides

AbstractSb4O5Br2 crystallizes plate‐shaped in the monoclinic space group P21/c with the lattice parameters a=660.82(5) pm, b=513.71(4) pm, c=1346.35(9) pm and β=97.876(3)° for Z=2. Its crystal structure contains {[Sb4O5]2+} layers with connected [(Sb1)O3+1]5− ψ1‐units and undisturbed pyramidal [(Sb2)O3]3− ψ1‐units, where the free electron pair is counted as a pseudo‐ligand (ψ). The bromide anions required for charge compensation of these cationic {[Sb4O5]2+} layers form single sheets and are only bonded via van‐der‐Waals interactions in this crystal structure, as the nearest distance to antimony cations is at least 300 pm. NdSb2O4Br crystallizes plate‐shaped in the monoclinic space group P21/c as well, but with the lattice parameters a=896.24(6) pm, b=801.16(5) pm, c=799.27(5) pm and β=92.129(3)° for Z=4. The [NdO8]13− polyhedra are linked to each other via four edges and thus form fluorite‐related layers {[NdO ]5−}, which run parallel to the (100) plane. The [SbO3]3− anions share vertices to build chains {[SbO O ]−} along [001], which align parallel within the (100) plane. The isolated Br− anions arrange in layers and show a minimum distance of 319 pm to the next Sb3+ cation. ErSb2O4Br crystallizes plate‐shaped in the non‐centrosymmetric tetragonal space group P4212 with the lattice parameters a=774.76(4) pm, c=899.53(6) pm and c/a=1.161 for Z=4. The erbium‐oxygen environment appears to be roughly the same as in NdSb2O4Br, so the main difference is the linkage of the ψ1‐[SbO3]3− units. Four of these [SbO3]3− anions assemble in a ring structure {[Sb4O8]4−} by sharing corners. Layers of rings are located in the (001) plane and almost planar bromide‐anion slabs assemble between the antimony‐oxygen layers. In this article, all three crystal structures are compared with each other and single‐crystal Raman spectra were recorded and analyzed for NdSb2O4Br and ErSb2O4Br.

Electronic structure modulation in quinoline derivatives through substituent-mediated effects: Development of AIE fluorescent probes for Fe3+ detection in water samples

Iron (Fe3+) is an essential trace element in biological organisms. Abnormal concentrations of Fe3+ in aquatic possess the potential to disrupt normal physiological and metabolic processes in living organisms. Consequently, the pursuit of developing fluorescent probes for detecting Fe3+ concentrations in water samples is highly significant. The lone electron pair on the nitrogen atom of quinoline demonstrates outstanding coordination capabilities, enabling the selective detection of metal ions through coordination. Nevertheless, the interaction between metal ions and quinoline-based fluorescent probes tends to lead to nanoparticle aggregation, causing aggregation-caused quenching (ACQ) phenomena. This severely restricts the practical application of these probes. To address this challenge, the study utilizes quinoline as the foundational framework and modulates the excited-state electronic structure of quinoline derivatives through substituent effects. This facilitates the transition from ACQ to aggregation-induced emission (AIE). By integrating theoretical calculations, the paper proposes a comprehensive strategy for designing AIE molecules based on quinoline. This contribution provides innovative perspectives on AIE molecule design. Ultimately, the AIE property of the 8-MQB molecule is harnessed to develop a fluorescent probe capable of detecting Fe3+ in water samples. The fluorescence intensity exhibits a robust linear correlation with Fe3+ concentrations within the range of 5.0 μM to 0.3 mM. Moreover, the probe demonstrates exceptional resistance to interference from other metal ions. In conclusion, this research presents a universal strategy for designing AIE molecules and introduces an AIE probe for the rapid detection of Fe3+ concentrations in water samples.

Mechanism of polyaspartic acid as acid-base regulation depressant in reverse flotation separation of molybdenite and talc

The separation of talc and molybdenite through flotation has become a significant issue. The current inorganic and organic depressants demonstrate inadequate selectivity and limited efficacy in both positive flotation and reverse flotation of molybdenite. In this study, the utilization of the highly efficient green agent polyaspartic acid (PASP) as a molybdenite depressant was explored to investigate its pH-dependent acid-base depression mechanism. In the case of pH 4.0, molybdenite exhibited effective depression, talc was floated, PASP was desorbed at pH 10.0, and molybdenite was activated. In this study, the impact of electrostatic force on the adsorption process of PASP and examined the mechanism of PASP on molybdenite surface were studied by means of micro-flotation experiments, zeta potential measurements, analysis of solution chemistry, Fourier Transform Infrared Spectrometer (FT-IR) analysis, Ultraviolet–visible spectroscopy (UV–Vis) study, and X-ray photoelectron spectroscopy (XPS) detections. PASP produced chemisorption through the coordination of O or N atoms lone pair electrons with Mo2+ on the molybdenite surface. In this process, electrostatic repulsion determines whether the mineral can come into contact with PASP.

Noncollinear Electric Dipoles in a Polar Chiral Phase of CsSnBr3 Perovskite.

Polar and chiral crystal symmetries confer a variety of potentially useful functionalities upon solids by coupling otherwise noninteracting mechanical, electronic, optical, and magnetic degrees of freedom. We describe two phases of the 3D perovskite, CsSnBr3, which emerge below 85 K due to the formation of Sn(II) lone pairs and their interaction with extant octahedral tilts. Phase II (77 K < T < 85 K, space group P21/m) exhibits ferroaxial order driven by a noncollinear pattern of lone pair-driven distortions within the plane normal to the unique octahedral tilt axis, preserving the inversion symmetry observed at higher temperatures. Phase I (T < 77 K, space group P21) additionally exhibits ferroelectric order due to distortions along the unique tilt axis, breaking both inversion and mirror symmetries. This polar and chiral phase exhibits second harmonic generation from the bulk and pronounced electrostriction and negative thermal expansion along the polar axis (Q22 ≈ 1.1 m4 C-2; αb = -7.8 × 10-5 K-1) through the onset of polarization. The structures of phases I and II were predicted by recursively following harmonic phonon instabilities to generate a tree of candidate structures and subsequently corroborated by synchrotron X-ray powder diffraction and polarized Raman and 81Br nuclear quadrupole resonance spectroscopies. Preliminary attempts to suppress unintentional hole doping to allow for ferroelectric switching are described. Together, the polar symmetry, small band gap, large spin-orbit splitting of Sn 5p orbitals, and predicted strain sensitivity of the symmetry-breaking distortions suggest bulk samples and epitaxial films of CsSnBr3 or its neighboring solid solutions as candidates for bulk Rashba effects.

Crystallization management of CsPbI2Br perovskites by PbAc2-incorporated twice spin-coating process for efficient and stable CsPbI2Br perovskite solar cells

CsPbI2Br perovskite solar cell has been extensively studied due to its exceptional thermal stability and relatively stable perovskite phase structure. However, the presence of bromine leads to a rapid crystallization rate of CsPbI2Br films, resulting in small grain size and high defect density. Additionally, CsPbI2Br demonstrates poor light absorption due to its wide bandgap. Therefore, it is crucial to control the crystallization rate and increase the film thickness to reduce defect density, enhance light absorption, and improve photovoltaic performance. In this study, we utilized a PbAc2-incorporated twice spin-coating (PTS) process to address these issues. Initially, PbAc2 was added to the CsPbI2Br precursor solution to form a CsPbI2Br film, which was then coated with the CsPbI2Br precursor solution to produce the PTS film. Ac− can delay the perovskite crystallization, leading to the formation of thicker and denser CsPbI2Br films. Moreover, lone-pair electrons of the oxygen atom provided by Ac− formed coordination bonds with under-coordinated Pb2+ ions to fill halogen ion vacancies, thereby reducing the defect density. Ultimately, the PTS CsPbI2Br device achieved a peak power conversion efficiency (PCE) of 16.19% and maintained 96.7% of its initial PCE over 1500 h at room temperature under 25% relative humidity without any encapsulation.

Structural Evolution and Photoluminescence Quenching across the FASnI3-xBrx (x = 0-3) Perovskites.

One of the primary methods for band gap tuning in metal halide perovskites has been halide (I/Br) mixing. Despite widespread usage of this type of chemical substitution in perovskite photovoltaics, there is still little understanding of the structural impacts of halide alloying, with the assumption being the formation of ideal solid solutions. The FASnI3-xBrx (x = 0-3) family of compounds provides the first example where the assumption breaks down, as the composition space is broken into two unique regimes (x = 0-2.9; x = 2.9-3) based on their average structure with the former having a 3D and the latter having an extended 3D (pseudo 0D) structure. Pair distribution function (PDF) analyses further suggest a dynamic 5s2 lone pair expression resulting in increasing levels of off-centering of the central Sn as the Br concentration is increased. These antiferroelectric distortions indicate that even the x = 0-2.9 phase space behaves as a nonideal solid-solution on a more local scale. Solid-state NMR confirms the difference in local structure yielding greater insight into the chemical nature and local distributions of the FA+ cation. In contrast to the FAPbI3-xBrx series, a drastic photoluminescence (PL) quenching is observed with x ≥ 1.9 compounds having no observable PL. Our detailed studies attribute this quenching to structural transitions induced by the distortions of the [SnBr6] octahedra in response to stereochemically expressed lone pairs of electrons. This is confirmed through density functional theory, having a direct impact on the electronic structure.

Azophosphines: Synthesis, Structure and Coordination Chemistry.

The conceptual replacement of nitrogen with phosphorus in common organic functional groups unlocks new properties and reactivity. The phosphorus-containing analogues of triazenes are underexplored but offer great potential as flexible and small bite-angle ligands. This manuscript explores the synthesis and characterisation of a family of air-stable azophosphine-borane complexes, and their subsequent deprotection to the free azophosphines. These compounds are structurally characterised, both experimentally and computationally, and highlight the availability of the phosphorus lone pair for coordination. This is confirmed by demonstrating that neutral azophosphines can act as ligands in Ru complexes, and can coordinate as monodentate or bidentate ligands in a controlled manner, in contrast to their nitrogen analogues.

Competing electrophilic substitution and oxidative polymerization of arylamines with selenium dioxide.

This article describes the detailed analysis of the reaction between arylamines, such as aniline, o-anisidine, and methyl anthranilate, with selenium dioxide in acetonitrile. A systematic analysis of the reaction products with the help of 77Se NMR and single-crystal X-ray crystallography revealed that the reaction progress follows three major reaction pathways, electrophilic selenation, oxidative polymerization, and solvent oxidation. For aniline and o-anisidine, predominant oxidative polymerization occurred, leading to the formation of the respective polyaniline polymers as major products. For methyl anthranilate, the oxidative polymerization was suppressed due to the delocalization of amine lone pair electrons over the adjacent carboxylate function, which prompted the selenation pathway, leading to the formation of two of the isomeric diorganyl selenides of methyl anthranilate. The diaryl selenides were structurally characterized using single-crystal X-ray diffraction. Density functional theory calculations suggest that the highest occupied molecular orbital of methyl anthranilate was deeply buried, which suppressed the oxidative polymerization pathway. Due to solvent oxidation, oxamide formation was also noticed to a considerable extent. This study provides that utmost care must be exercised while using SeO2 as an electrophile source in aromatic electrophilic substitution reactions.

Providing a Photovoltaic Performance Enhancement Relationship from Binary to Ternary Polymer Solar Cells via Machine Learning.

Ternary polymer solar cells (PSCs) are currently the simplest and most efficient way to further improve the device performance in PSCs. To find high-performance organic photovoltaic materials, the established connection between the material structure and device performance before fabrication is of great significance. Herein, firstly, a database of the photovoltaic performance in 874 experimental PSCs reported in the literature is established, and three different fingerprint expressions of a molecular structure are explored as input features; the results show that long fingerprints of 2D atom pairs can contain more effective information and improve the accuracy of the models. Through supervised learning, five machine learning (ML) models were trained to build a mapping of the photovoltaic performance improvement relationship from binary to ternary PSCs. The GBDT model had the best predictive ability and generalization. Eighteen key structural features from a non-fullerene acceptor and the third components that affect the device's PCE were screened based on this model, including a nitrile group with lone-pair electron, a halogen atom, an oxygen atom, etc. Interestingly, the structural features for the enhanced device's PCE were essentially increased by the Jsc or FF. More importantly, the reliability of the ML model was further verified by preparing the highly efficient PSCs. Taking the PM6:BTP-eC9:PY-IT ternary PSC as an example, the PCE prediction (18.03%) by the model was in good agreement with the experimental results (17.78%), the relative prediction error was 1.41%, and the relative error between all experimental results and predicted results was less than 5%. These results indicate that ML is a useful tool for exploring the photovoltaic performance improvement of PSCs and accelerating the design and application with highly efficient non-fullerene materials.

Kobellite homologues from the Boliden Au–Cu–(As) deposit, Sweden: jigsaw patterning via nanoscale intergrowths in chessboard structures

Abstract Sulfosalt assemblages in a specimen from the Boliden Au–Cu–(As) deposit in northern Sweden, comprise micrometre to nanometre scale intergrowths of Se-rich izoklakeite and tintinaite with average formulae and calculated homologue number (N) given as: (Cu1.88Fe0.18)2.06(Pb22.92Ag1.47Cd0.01Zn0.01)24.41(Sb13.12Bi8.69)21.8(S50.19Se6.43Te0.12)56.73,N = 3.83, and (Cu1.31Fe0.74)2.05(Pb10.58Ag0.18Cd0.05Zn0.02)10.83(Sb10.2Bi5.23)15.43(S32.22Se2.46)34.7, N = 2.05, respectively. Tintinaite coexists with (Bi, Se)-rich jamesonite. High-angle annular dark field scanning transmission electron microscopy (HAADF STEM) imaging reveals chessboard structures comprising PbS and SnS modules with the number of atoms in the octahedral (M) sites counted as: n1 = 18 and n2 = 8 for tintinaite and n1 = 30 and n2 = 16 for izoklakeite. The homologue number can be calculated using the formula: N = (n1/6)–1 and N = n2/4 for PbS and SnS modules giving NTti = 2 and NIz = 4. A new N = 3 homologue, defined by n = 12 and n = 24 SnS and PbS modules, respectively, is identified as single or double units within areas with intergrowths between kobellite and izoklakeite. HAADF STEM imaging also reveals features attributable to lone electron pair micelles within the Sb-rich kobellite homologues. Atomic-resolution EDS STEM chemical mapping of Pb–Bi–Sb-sulfosalts shows a correlation with crystal structural modularity. The maps also highlight sites in the SnS modules of tintinaite in which Sb &gt; Bi. Coherent nanoscale intergrowths between tintinaite and izoklakeite define jigsaw patterns evolving from chessboard structures and are considered to have formed during co-crystallisation of the two phases. Displacement textures and crosscutting veinlets (a few nm in width) are interpreted as evidence for superimposed syn-metamorphic deformation and are associated with the redistribution of Bi and Se. Imaging and mapping using HAADF STEM techniques is well suited to characterisation of Pb–Sb–Bi-sulfosalt phases, offering largely untapped potential to unravel the evolution of chessboard structures with applications across mineralogy but also extending into allied fields.

The n,π* States of Heteroaromatics: When are They the Lowest Excited States and in What Way Can They Be Aromatic or Antiaromatic?

Heteroaromatic molecules are found in areas ranging from biochemistry to photovoltaics. We analyze the n,π* excited states of 6π-electron heteroaromatics with in-plane lone pairs (nσ, herein n) and use qualitative theory and quantum chemical computations, starting at Mandado's 2n + 1 rule for aromaticity of separate spins. After excitation of an electron from n to π*, a (4n + 2)π-electron species has 2n + 2 πα-electrons and 2n + 1 πβ-electrons (or vice versa) and becomes πα-antiaromatic and πβ-aromatic. Yet, the antiaromatic πα- and aromatic πβ-components seldom cancel, leading to residuals with aromatic or antiaromatic character. We explore vertically excited triplet n,π* states (3n,π*), which are most readily analyzed, but also singlet n,π* states (1n,π*), and explain which compounds have n,π* states with aromatic residuals as their lowest excited states (e.g., pyrazine and the phenyl anion). If the πβ-electron population becomes more (less) uniformly distributed upon excitation, the system will have an (anti)aromatic residual. Among isomers, the one that has the most aromatic residual in 3n,π* is often of the lowest energy in this state. Five-membered ring heteroaromatics with one or two N, O, and/or S atoms never have n,π* states as their first excited states (T1 and S1), while this is nearly always the case for six-membered ring heteroaromatics with electropositive heteroatoms and/or highly symmetric (D2h) diheteroaromatics. For the complete compound set, there is a modest correlation between the (anti)aromatic character of the n,π* state and the energy gap between the lowest n,π* and π,π* states (R2 = 0.42), while it is stronger for monosubstituted pyrazines (R2 = 0.84).

Nonlinear Optical Effects of Hybrid Antimony(III) Halides Induced by Stereoactive 5s2 Lone Pairs and Trimethylammonium Cations.

Organic-inorganic hybrid metal halides have unique optical and electronic properties, which are advantageous in the study of nonlinear optical materials. To investigate the effect of stereoactive lone pair electrons and the induction of organic cations on the structure of hybrid antimony(III) halides on nonlinear optics, we synthesize two noncentrosymmetric hybrid antimony(III)-based halide single crystals (TMA)3Sb2X9 (TMA = NH(CH3)3+, X = Cl, Br) by a room-temperature slow evaporation method, and their single-crystal structures, phase transition, X-ray photoelectron spectroscopy, and energy-band structure calculations are studied. More importantly, second-harmonic generation results of (TMA)3Sb2X9 (X = Cl, Br) are about 0.7 and 0.8 × KH2PO4(KDP), respectively. Interestingly, (TMA)3Sb2Cl9 single crystals undergo a reversible structural transition from Pc (No. 7) at room temperature to P21/c (No. 14) at 400 K, while the (TMA)3Sb2Br9 single crystals belong to the noncentrosymmetric space group R3c (No. 161), which clarifies the previous results. This work not only deepens the understanding of the role in lone pair electrons and organic cations in the structural induction in antimony-based halide perovskite materials but also provides guidance for subsequent nonlinear optical explorations.

Bisgermylene-Stabilized Stannylone: Catalytic Reduction of Nitrous Oxide and Nitro Compounds via Element-Ligand Cooperativity.

This study describes the synthesis, structural characterization, and catalytic application of a bis(germylene)-stabilized stannylone (2). The reduction of digermylated stannylene (1) with 2.2 equiv of potassium graphite (KC8) leads to the formation of stannylone 2 as a green solid in 78% yield. Computational studies showed that stannylone 2 possesses a formal Sn(0) center and a delocalized 3-c-2-e π-bond in the Ge2Sn core, which arises from back-donation of the p-type lone pair electrons on the Sn atom to the vacant orbitals of the Ge atoms. Stannylone 2 can serve as an efficient precatalyst for the selective reduction of nitrous oxide (N2O) and nitroarenes (ArNO2) with the formation of dinitrogen (N2) and hydrazines (ArNH-NHAr), respectively. Exposure of 2 with N2O (1 atm) resulted in the insertion of two oxygen atoms into the Ge-Ge and Ge-Sn bonds, yielding the germyl(oxyl)stannylene (3). Moreover, the stoichiometric reaction of 2 with 1-chloro-4-nitrobenzene afforded an amido(oxyl)stannylene (4) through the complete scission of the N-O bonds of the nitroarene. Stannylenes 3 and 4 serve as catalytically active species for the catalytic reduction of nitrous oxide and nitroarenes, respectively. Mechanistic studies reveal that the cooperation of the low-valent Ge and Sn centers allows for multiple electron transfers to cleave the N-O bonds of N2O and ArNO2. This approach presents a new strategy for catalyzing the deoxygenation of N2O and ArNO2 using a zerovalent tin compound.

Silyliumylidene Ion Stabilized by Two σ-Donating Ni(0)- and Pd(0)-Fragments.

A silyliumylidene ion 2 stabilized by two σ-donating Ni(0)- and Pd(0)-fragments was successfully synthesized. Due to the σ-donation of M→Si interactions, 2 presents a pyramidalized cationic silicon center with a localized lone pair. The additional coordination of basic Pd(0) fragment to the mono-Ni(0)-stabilized silyliumylidene 1 results in a higher HOMO level and an unchanged HOMO-LUMO gap and thus, 2 remains highly reactive. Interestingly, the coordination mode at the Si center is closely related to the nature of M-ligands. Indeed, the donor/donor-stabilized silyliumylidene ion 2 has been transformed into a donor/acceptor-stabilized ion 13, featuring a trigonal planar Si center with a vacant orbital, just via a ligand exchange reaction from PCy3/NHC toward PMe3.

Iodine-doped carbon nanotubes boosting the adsorption effect and conversion kinetics of lithium-sulfur batteries

Compared with lithium-ion batteries (LIBs), lithium-sulfur batteries (LSBs), based on electrochemical reactions involving multi-step 16-electron transformations provide higher specific capacity (1672 mAh g−1) and specific energy (2600 Wh kg−1), exhibiting great potential in the field of energy storage. However, the inherent insulation of sulfur, slow electrochemical reaction kinetics and detrimental shuttle-effect of lithium polysulfides (LiPSs) restrict the development of LSBs in practical applications. Herein, the iodine-doped carbon nanotubes (I-CNTs) is firstly reported as sulfur host material to the enhance the adsorption-conversion kinetics of LSBs. Iodine doping can significantly improve the polarity of I-CNTs. Iodine atoms with lone pair electrons (Lewis base) in iodine-doped CNTs can interact with lithium cations (Lewis acidic) in LiPSs, thereby anchoring polysulfides and suppressing subsequent shuttling behavior. Moreover, the charge transfer between iodine species (electron acceptor) and CNTs (electron donor) decreases the gap band and subsequently improves the conductivity of I-CNTs. The enhanced adsorption effect and conductivity are beneficial for accelerating reaction kinetics and enhancing electrocatalytic activity. The in-situ Raman spectroscopy, quasi in-situ electrochemical impedance spectroscopy (EIS) and Li2S potentiostatic deposition current–time (i-t) curves were conducted to verify mechanism of complex sulfur reduction reaction (SRR). Owing to above advantages, the I-CNTs@S composite cathode exhibits an ultrahigh initial capacity of 1326 mAh g−1 as well as outstanding cyclicability and rate performance. Our research results provide inspirations for the design of multifunctional host material for sulfur/carbon composite cathodes in LSBs.

Enhance the performance of OER electrocatalyst via synergistic oxygen vacancies and NiFe2O4-phosphorene heterostructure

The exfoliated black phosphorus nanosheets (EBP, phosphorene) is considered as a highly anticipated electrocatalyst for oxygen evolution reaction (OER) because of its unique electron structure. However, the poor stability and conductivity of EBP limit its application potential. In this paper, a heterostructure of EBP and nickel ferrite with oxygen vacancies (NFO-V-EBP) is designed by using a simple ultrasound and electronic regulation of EBP. NFO-V forms P-Ni bonds and P-O-M (M=Ni/Fe) bonds by interacting with the active lone pair electrons on the surface of EBP, which passivates EBP to improve its stability and provide more active sites. In situ Raman testing is used to assist in demonstrating the cooperative effect of EBP and oxygen vacancy, which reduced the potential barrier of OER reaction. NFO-V-EBP heterostructure exhibits excellent electrocatalytic performance for alkaline OER, showing overpotential of 243 mV at current density of 10 mA cm-2 and Tafel slope of 39 mV dec-1. It also has excellent long-term stability, at a density of 10 mA cm-2 with no significant increase in overpotential observed after nearly 100 hours under the chronoamperometric method.

Aromatic Rules of C22H122+/2•/2-: Flexibility in Electronic Structures of 2D Superatomic Molecules.

Triangulene (C22H122•), a nonclassic non-Kekulé polycyclic aromatic hydrocarbon, is identified to be aromatic by structural and magnetic criteria. However, its aromatic origin remains confusing. Herein, the aromatic rules of C22H122• and its two charged counterparts C22H122+/2- were investigated on the basis of a recently developed two-dimensional (2D) superatomic-molecule theory. [C22H12]2+/2•/2- exhibit obvious local aromatic characters and can be regarded as [◊N3◊O3]+, [◊N3◊O3]-, and ◊N3◊F3 superatomic molecules, respectively, where ◊N, ◊O, and ◊F denote 2D superatoms bearing 3π, 4π, and 5π electrons. [C22H12]2+/2- realize electronic shell closure via superatomic lone pairs and covalent bonds, mimicking simple molecules, whereas the α-π and β-π electrons in C22H122• follow the superatomic bonding patterns of C22H122- and C22H122+, respectively. Furthermore, based on the local character in 2D superatomic molecules, a doped nanoporous graphene, namely, C9N12B monolayer, was predicted. The material possesses excellent dynamical and thermodynamical stability, as well as a wide band gap of 2.77 eV, positioning it as a promising 2D material for future electronic applications.

Fine-tuning Fluorescence of Amlodipine Adopting on Blocking of Photoinduced Electron Transfer (PET): Application in Human Plasma.

Assessing medication adherence through the determination of antihypertensive drugs in biological matrices holds significant importance. Amlodipine (AP), a potent antihypertensive medication extensively prescribed for hypertensive patients, is particularly noteworthy in this context. This article aims to introduce a rapid, simple, improved sensitivity, and reproducibility in detecting AP in its pure form, tablet formulation, and spiked human plasma than the other reported methods. The proposed method utilizes a fluorescence approach, relying on the inhibition of the intramolecular photoinduced electron transfer (PET) effect of the lone pair of the N-atom in the primary amino moiety of AP. This inhibition is achieved by acidifying the surrounding medium using 0.2M acetic acid. By blocking PET, the target AP drug is sensitively detected, at [Formula: see text] 423nm over a concentration range 25-500 ng mL- 1 showcasing an exceptionally low quantitation limit of 1.41 ng mL- 1. Notably, this innovative technique was successfully applied to detect AP in its solid dosage form and spiked human plasma. Remarkably, matrix interference was found to be insignificant, underscoring the robustness and applicability of the established approach. The combination of speed, sensitivity, and reproducibility makes this method particularly suitable for assessing medication adherence in patients prescribed AP for hypertension.