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Ultrafast transient vibrational action spectra of cryogenically cooled Re(CO)3(CH3CN)3+ ions are presented. Nonlinear spectra were collected in the time domain by monitoring the photodissociation of a weakly bound N2 messenger tag as a function of delay times and phases between a set of three infrared pulses. Frequency-resolved spectra in the carbonyl stretch region show relatively strong bleaching signals that oscillate at the difference frequency between the two observed vibrational features as a function of the pump–probe waiting time. This observation is consistent with the presence of nonlinear pathways resulting from underlying cross-peak signals between the coupled symmetric–asymmetric C≡O stretch pair. The successful demonstration of frequency-resolved ultrafast transient vibrational action spectroscopy of dilute molecular ion ensembles provides an exciting, new framework for the study of molecular dynamics in isolated, complex molecular ion systems. [ABSTRACT FROM AUTHOR]

Photoionization spectroscopy and mass spectrometry of doped helium (He) nanodroplets rely on the ability to efficiently detect ions and/or electrons. Using a commercial quadrupole mass spectrometer and a photoelectron–photoion coincidence spectrometer, we systematically measure yields of ions and electrons created in pure and doped He nanodroplets in a wide size range and in two ionization regimes—direct ionization and secondary ionization after resonant photoexcitation of the droplets. For two different types of dopants (oxygen molecules, O2, and lithium atoms, Li), we infer the optimal droplet size to maximize the yield of ejected ions. When dopants are ionized by charge-transfer to photoionized He nanodroplets, the highest yield of O2 and Li ions is detected for a mean size of ∼ 5 × 1 0 4 He atoms per nanodroplet. When dopants are Penning ionized via photoexcitation of the He droplets, the highest yield of O2 and Li ions is detected for ∼ 1 0 3 and ∼ 1 0 5 He atoms per droplet, respectively. At optimum droplet sizes, the detection efficiency of dopant ions in proportion to the number of primary photoabsorption events is up to 20% for charge-transfer ionization of O2 and 2% for Li, whereas for Penning ionization it is 1% for O2 and 4% for Li. Our results are instrumental in determining optimal conditions for mass spectrometric studies and photoionization spectroscopy of molecules and complexes isolated in He nanodroplets. [ABSTRACT FROM AUTHOR]

The radio frequency ion thruster (RIT) is an electric propulsion device that utilizes radio frequency (RF) power to ionize propellants; thus, its performance is influenced by the frequency and matching network of the RF. In this study, an L&T type wide-range matching network was employed to experimentally investigate the performance of a miniature RIT with 4 cm diameter at different frequencies. The experimental results show that changing the matching parameters of the L&T network at the same frequency leads to changes in the effective quality factor and varying performances of the thruster; under similar effective quality factors, changing the frequency does not significantly affect the performance of the thruster; however, the plasma resistance exhibits frequency dependence. As the frequency increases, the effective collision frequency increases, leading to an increase in plasma resistance, which is beneficial for improving the performance of the thruster at high frequencies. Finally, a set of methods for quickly comparing the performance of RITs was summarized based on the effective quality factor. These research results are also instructive for improving the ionization of induction-coupled discharge devices of other sizes. [ABSTRACT FROM AUTHOR]

In this paper, we present a continuation of our research on modeling electrolyte solutions within charged pores. We make use of the model developed by Blossey et al. [Phys. Rev. E 95, 060602 (2017)], which takes into account the structural interactions between ions through a bilinear form over the gradients of local ionic concentrations in the grand thermodynamic potential, as well as their steric interactions through the lattice gas model. The structural interactions may describe the effects of the molecular structure of ions at a phenomenological level. For example, these effects include steric effects due to non-spherical shapes of ions, their conformational lability, and solvent effects. In addition, we explore their specific interactions with the pore walls by incorporating external attractive potentials. Our primary focus is on observing the behavior of ionic concentration profiles and the disjoining pressure as the pore width changes. By starting with the local mechanical equilibrium condition, we derive a general expression for the disjoining pressure. Our findings indicate that considering the structural interactions of ions leads to a pronounced minimum on the disjoining pressure profiles at small pore widths. We attribute this minimum to the formation of electric double layers on the electrified surfaces of the pore. In addition, our results demonstrate that the inclusion of the attractive interactions of ions with the pore walls enhances this minimum and shifts it to smaller pore thicknesses. Our theoretical discoveries may be useful for those involved in supercapacitor electrochemical engineering, particularly when working with porous electrodes that have been infused with concentrated electrolyte solutions. [ABSTRACT FROM AUTHOR]

The metastability and the dissociation processes of the OCS3+ states produced by the S 2p double Auger decay of OCS are investigated by multi-electron-ion coincidence spectroscopy using a magnetic bottle electron spectrometer. The spectra of the OCS3+ states filtered for the production of individual ions are derived by four-fold (or five-fold) coincidence among three electrons and a product ion (or two ions). The ground OCS3+ state is confirmed to be metastable in the 10 µs regime. The OCS3+ states relevant to the individual channels of two- and three-body dissociations are clarified. [ABSTRACT FROM AUTHOR]

The interdomain electron transfer (IET) between the catalytic flavodehydrogenase domain and the electron-transferring cytochrome domain of cellobiose dehydrogenase (CDH) plays an essential role in biocatalysis, biosensors and biofuel cells, as well as in its natural function as an auxiliary enzyme of lytic polysaccharide monooxygenase. We investigated the mobility of the cytochrome and dehydrogenase domains of CDH, which is hypothesised to limit IET in solution by small angle X-ray scattering (SAXS). CDH from Myriococcum thermophilum (syn. Crassicarpon hotsonii, syn. Thermothelomyces myriococcoides) was probed by SAXS to study the CDH mobility at different pH and in the presence of divalent cations. By comparison of the experimental SAXS data, using pair-distance distribution functions and Kratky plots, we show an increase in CDH mobility at higher pH, indicating alterations of domain mobility. To further visualise CDH movement in solution, we performed SAXS-based multistate modelling. Glycan structures present on CDH partially masked the resulting SAXS shapes, we diminished these effects by deglycosylation and studied the effect of glycoforms by modelling. The modelling shows that with increasing pH, the cytochrome domain adopts a more flexible state with significant separation from the dehydrogenase domain. On the contrary, the presence of calcium ions decreases the mobility of the cytochrome domain. Experimental SAXS data, multistate modelling and previously reported kinetic data show how pH and divalent ions impact the closed state necessary for the IET governed by the movement of the CDH cytochrome domain.

A supramolecular zwitterionic hydrogel based on polyacrylamide/carboxylated cellulose nanofibers/betaine citrate is constructed. The non-covalent interactions within the supramolecular zwitterionic hydrogels results in the formation of inter-crosslinked polymer networks. The strong coordination between betaine citrate with negative loading groups and zinc ions leads to rapid transfer of zinc ions by molecular slippage inside the polymer, which improved the transfer kinetics of zinc ions. Meanwhile, anchoring of various polar groups in the supramolecular zwitterionic hydrogel on the surface of the zinc anode provides active sites for the rapid and uniform deposition of zinc ions. [Display omitted] • Molecular slip mechanisms enhance the diffusion kinetics of Zn2+. • Zwitterionic coordination effect improves deposition kinetics. • Polar group anchoring effects protect zinc anodes. • Zn mental battery exhibits outstanding cycle performance. The severe hydrogen evolution reaction and parasitic side reaction on Zn anode are the key issues which hinder the development of aqueous Zn-based energy storage devices. Herein, a polyacrylamide/carboxylated cellulose nanofibers/betaine citrate supramolecular zwitterionic hydrogels with molecular slip effects are proposed for enhancing Zn2+ diffusion and protecting Zn anodes. Non-covalent interactions within supramolecular hydrogels forms the skeleton for molecular slip and the strong coordination of carboxyl and amino groups with Zn2+ further facilitates the rapid Zn2+ transfer. Additionally, anchoring carboxyl and amino groups at the anode promotes the uniform deposition of Zn2+and protects Zn anode. On the basis of molecular slip mechanism and anchoring effect in the supramolecular zwitterionic hydrogels, Zn||Zn symmetric batteries undergo 800 h of stable electroplating stripping at a depth of discharge of 80 %. Zn||Cu asymmetric batteries exhibit an impressive average coulombic efficiency of 99.4 % over a remarkable span of 900 cycles at a current density of 15 mA cm−2. Furthermore, Zn||NH 4 V 4 O 10 batteries successfully undergo over 1,000 cycles at a current density of 0.5 A g−1. Intrinsic ion diffusion mechanism of supramolecular hydrogel electrolytes provides an original strategy for the application of high-performance Zn-based energy storage devices. [ABSTRACT FROM AUTHOR]

Gas chromatography–mass spectrometry (GC–MS) is a cornerstone technique for analyses of volatile and semivolatile compounds, constantly evolving to meet new challenges. The adoption of time‐of‐flight mass spectrometers (TOFMS) has enhanced GC–MS with faster spectral acquisition and broader mass coverage, enabling rapid GC separations. Multireflecting TOFMS (MRT) further improves resolution compared to traditional single‐reflecting TOFMS, facilitating the detection of minor analytes within complex matrices. This paper presents a significant improvement in MRT sensitivity and dynamic range achieved through an ion beam compression within the ion guide and the use of a conventionally oriented orthogonal accelerator. Sensitivity is improved to 100 000 ion/pg at a resolution of R = 25,000, enabling the detection of low fg analyte quantities within 3 μg of matrix material into MS. The demonstrated linear dynamic range exceeding 6 orders of magnitude potentially enables even deeper exploration of complex mixtures with a bench top instrument. [ABSTRACT FROM AUTHOR]

In this study, a Fe‐MOF was synthesized via a coprecipitation procedure and then used as support for stabilizing Ag ions and producing three‐dimensional cluster bud Ag2O@Fe‐MOF nanoflower composite (3D CB Ag2O@Fe‐MOF NFC) by microwave irradiation. The synthesized 3D CB Ag2O@Fe‐MOF NFC was applied as a heterogeneous nano‐organocatalyst in green and new preparation of naphthopyranopyrimidines via three‐component condensation of aryl aldehydes, β‐naphthol, and barbituric acids in the solvent‐free conditions at 100°C. Convenience, solvent‐free conditions, good yield, and short reaction time make this strategy a promising candidate compared to other methods. The reusability and high efficiency of this catalyst four times without any notable loss of its activity makes this strategy attractive for large‐scale eco‐friendly applications. [ABSTRACT FROM AUTHOR]

The sensitivity and accuracy of identifying volatile organic compounds using mass spectrometric gas analyzers operation in the electron ionization mode can be enhanced by increasing the number of ions formed in the ion source by varying the energy of ionizing electrons. The paper presents a comparison of data obtained by electron impact ionization at electron energy (EE) in the range of 25–105 eV for a number of organic substances belonging to different classes of organic compounds. an analysis using similarity matrices based on various similarity metrics was performed to interpret the dynamics of changes in the intensities of fragment ion peaks, and the influence of EE on the formation probability of the main fragment species of the substances under study and, accordingly, on the resemblance of a recorded mass spectrum to the reference mass spectrum from the database was shown. [ABSTRACT FROM AUTHOR]

Theories of bulk coacervation of oppositely charged polyelectrolytes (PE) obscure single molecule level thermodynamic details, considered significant for coacervate equilibrium, whereas simulations account for only pairwise Coulomb interaction. Also, studies of effects of asymmetry on PE complexation are rare compared to symmetric PEs. We develop a theoretical model, accounting for all entropic and enthalpic contributions at the molecular level, and the mutual segmental screened Coulomb and excluded volume interactions between two asymmetric PEs, by constructing a Hamiltonian following Edwards and Muthukumar. Assuming maximal ion-pairing in the complex, the system free energy comprising configurational entropy of the polyions and free-ion entropy of the small ions is minimized. The effective charge and size of the complex, larger than sub-Gaussian globules as for symmetric chains, increase with asymmetry in polyion length and charge density. The thermodynamic drive for complexation is found to increase with ionizability of symmetric polyions and with a decrease in asymmetry in length for equally ionizable polyions. The crossover Coulomb strength demarcating the ion-pair enthalpy-driven (low strength) and counterion release entropy-driven (high strength) is marginally dependent on the charge density, because so is the degree of counterion condensation, and strongly dependent on the dielectric environment and salt. The key results match the trends in simulations. The framework may provide a direct way to calculate thermodynamic dependencies of complexation on experimental parameters such as electrostatic strength and salt, thus to better analyze and predict observed phenomena for different sets of polymer pairs. [ABSTRACT FROM AUTHOR]

The ion emission properties of laser-produced plasmas as a function of laser intensities between 4–50 GW cm − 2 and varying angles with respect to the target normal were investigated. The plasmas were produced by focusing 1064 nm, 6 ns pulses from an Nd:YAG laser on various metal targets. The targets used for this study include Ti, Mo, and Gd (Z = 22 , 42 , 64). It is noted that all ion profiles are composed of multiple peaks—a prompt emission peak trailed by three ion peaks (ultrafast, fast, and thermal). Experimentally, it is shown that each of these ion peaks follows a unique trend as a function of laser intensity, angle, and distance away from the target. Theoretically, it is shown that simple analytical models can be used to explain the properties of the ions. The variations in the ion velocity and density as a function of laser intensity are found to be in good agreement with theoretical models of sheath acceleration, isothermal self-similar expansion, and ablative plasma flow for various ion peaks. [ABSTRACT FROM AUTHOR]

Resonance electron attachment in a series of brominated diphenyl ethers, namely 4-bromodiphenyl ether (BDPE), 4-bromophenyl ether (BPE), and decabromodiphenyl ether (DBDE), was investigated in the gas phase by means of dissociative electron attachment spectroscopy. In addition to channels of dissociation into stable fragments, long-lived molecular negative ions with an average lifetime relative to autodetachment of the order of 60 µs were found for the last two molecules. In the case of BDPE and BPE, the most intense dissociation channel is the bromine anion, and for DBDE—the [C6Br5O]− anion. The [C6Br5O]− anion sequentially decomposes with the elimination of the bromide anion on a microsecond time scale, which is confirmed by the registration of metastable ions with an apparent mass of 12.8 a.m.u. The electron affinity of the studied molecules and the appearance energy of fragment ions were estimated with CAM-B3LYP/6-311+G(d,p). [ABSTRACT FROM AUTHOR]

Recombination of vibrationally cold N 2 + ions with electrons was studied in the temperature range of 140–250 K. A cryogenic stationary afterglow apparatus equipped with cavity ring-down spectrometer and microwave diagnostics was utilized to probe in situ the time evolutions of number densities of particular rotational and vibrational states of N 2 + ions and of electrons. The obtained value of the recombination rate coefficient for the recombination of the vibrational ground state of N 2 + with electrons is αv=0 = (2.95 ± 0.50) × 10−7(300/T)(0.28±0.07) cm3 s−1, while that for the first vibrationally excited state was inferred as αv=1 = (4 ± 4) × 10−8 cm3 s−1 at 250 K. [ABSTRACT FROM AUTHOR]

While the dissociative recombination (DR) of ground-state molecular ions with low-energy free electrons is generally known to be exothermic, it has been predicted to be endothermic for a class of transition-metal oxide ions. To understand this unusual case, the electron recombination of titanium oxide ions (TiO+) with electrons has been experimentally investigated using the Cryogenic Storage Ring. In its low radiation field, the TiO+ ions relax internally to low rotational excitation (≲100 K). Under controlled collision energies down to ∼ 2 meV within the merged electron and ion beam configuration, fragment imaging has been applied to determine the kinetic energy released to Ti and O neutral reaction products. Detailed analysis of the fragment imaging data considering the reactant and product excitation channels reveals an endothermicity for the TiO+ dissociative electron recombination of (+4 ± 10) meV. This result improves the accuracy of the energy balance by a factor of 7 compared to that found indirectly from hitherto known molecular properties. Conversely, the present endothermicity yields improved dissociation energy values for D0(TiO) = (6.824 ± 0.010) eV and D0(TiO+) = (6.832 ± 0.010) eV. All thermochemistry values were compared to new coupled-cluster calculations and found to be in good agreement. Moreover, absolute rate coefficients for the electron recombination of rotationally relaxed ions have been measured, yielding an upper limit of 1 × 10−7 cm3 s−1 for typical conditions of cold astrophysical media. Strong variation of the DR rate with the TiO+ internal excitation is predicted. Furthermore, potential energy curves for TiO+ and TiO have been calculated using a multi-reference configuration interaction method to constrain quantum-dynamical paths driving the observed TiO+ electron recombination. [ABSTRACT FROM AUTHOR]

Characterization of the inner-shell decay processes in molecules containing heavy elements is key to understanding x-ray damage of molecules and materials and for medical applications with Auger-electron-emitting radionuclides. The 1s hole states of heavy atoms can be produced by absorption of tunable x rays and the resulting vacancy decays characterized by recording emitted photons, electrons, and ions. The 1s hole states in heavy elements have large x-ray fluorescence yields that transfer the hole to intermediate electron shells that then decay by sequential Auger-electron transitions that increase the ion's charge state until the final state is reached. In molecules, the charge is spread across the atomic sites, resulting in dissociation to energetic atomic ions. We have used x-ray/ion coincidence spectroscopy to measure charge states and energies of Iq+ and Brq′+ atomic ions following 1s ionization at the I and Br K-edges of IBr. We present the charge states and kinetic energies of the two correlated fragment ions associated with core-excited states produced during the various steps of the cascades. To understand the dynamics leading to the ion data, we develop a computational model that combines Monte-Carlo/Molecular-Dynamics (MC/MD) simulations with a classical over-the-barrier model to track inner-shell cascades and redistribution of electrons in valence orbitals and nuclear motion of fragments. [ABSTRACT FROM AUTHOR]

The subject matter of the article is the thermophysical and mechanical properties of surface layers of structural materials using a quantum-mechanical approach. The aim of the article is to adjust the parameters of the heat conductivity and thermoelasticity problem, considering all possible external and internal thermal effects and the quantum-mechanical description of the material structure, for electrodes in vacuum-arc nanostructuring. The task to be solved is to perform calculations using the developed model for a copper cathode considering the energy spent on the formation of nanoparticles during ion-plasma processing with oxygen ions. The methods used are methods for solving nonlinear problems. The following results were obtained. 1. The nature of the dependencies of the maximum temperature, the expected volume of nanostructures, and the maximum depth of their formation on the energy of oxygen ions with charges z = 1 and z = 2 matches previously known dependencies obtained by the classical model, but under quantum-mechanical consideration, the maximum temperature values increase by 15%, the volume of the nanocluster increases by 50%, and the maximum depth of its occurrence increases by 1.5 times. 2. When selecting the parameters of ion-plasma processing for obtaining nanostructures with ion energies 100...500 eV, the previously proposed model with general thermophysical and mechanical properties of structural materials can be used. 3. For technologies with ion energies in the range of 103...2∙103 eV, the previously proposed model can be used but with quantum-mechanical effects of structural materials considered. 4) For technologies with ion energies above 104 eV, calculations should be performed using both approaches (the classical approach and the approach considering the quantum-mechanical properties of structural materials), and after comparison, the variant whose calculation results are closest to the experimental results should be used. Conclusions. The proposed theoretical model using the thermophysical, mechanical, and quantum-mechanical properties of structural materials can be used to adjust the technological parameters of ion-plasma processing to assess the formation of nanostructures in protective and strengthening coatings.

This article presents a new method for detecting oxytocin (OT) in nonhuman primate plasma using liquid chromatography-tandem mass spectrometry (LC/MS/MS). OT is a neuropeptide that affects social behavior, and current methods for measuring OT levels have limitations. The researchers developed a protocol for sample preparation and analysis using LC/MS/MS, which allowed for accurate measurement of OT concentrations in plasma. The study found that the method was accurate and precise, with a lower limit of quantification of 0.41 pg/mL. This is the first reported method with sufficient sensitivity to measure OT in nonhuman primate plasma. [Extracted from the article]

Charge-neutral hexadecanuclear nanoclusters [Co16(OH)4(ib)20(thme)2(Hthme)2(H2O)6]·MeCN·4H2O (1) and [Co16(OH)4(ib)20(thmp)2(Hthmp)2(H2O)6]·MeCN·4H2O (2) have been prepared from the reaction of Co(II) isobutyrate (Co(ib)2) with 1,1,1-tris(hydroxymethyl)ethane (H3thme) or 1,1,1-tris(hydroxymethyl)propane (H3thmp) and comprehensively characterized. Single-crystal X-ray diffraction reveals that the common mixed-valent centrosymmetric {Co(II)14Co(III)2} core of 1 and 2 represents an unprecedented arrangement of two planar {Co7} disk-like fragments with a central Co(III) ion surrounded by six Co(II) ions connected by two additional Co(II) ions. The two {Co7} fragments are non-coplanar and lie in parallel planes separated by a distance of 2.772 Å, with two additional Co(II) centers between these planes. Hirshfeld surface (HS) analysis was used to gain additional insight into the interactions responsible for the packing of nanoclusters in the title compounds. Magnetic characterization of 1 revealed that the 14 Co(II) centers exhibit predominantly ferromagnetic exchange interactions, but some antiferromagnetic exchange pathways are also present. [ABSTRACT FROM AUTHOR]

AgBiO3 is reported for the exclusive oxidation of Am3+ → AmO2+ at near-neutral pH conditions. Literature methods of AmO2+ generation are generally two-step processes; i.e., Am3+ → AmO22+ oxidation followed by AmO22+ → AmO2+ reduction. These methods for Am3+ → AmO2+ oxidation use high temperatures (80–100 °C) and/or several reagents, causing the in situ presence of the AmO2+-complex rather than the AmO2+aq ions. This not only interferes with the much-needed Am–Cm selectivity but also limits the use of AmO2+aq in any other experimental study. The single-step Am3+ → AmO2+ oxidation in the present work using AgBiO3 is done at 25 °C in a non-complexing medium at pH ∼4, making it a first-of-its-kind report. Am–Eu and Am–Cm separation in a single contact, with a separation factor >104, was achieved using the present method, which is unprecedented among aqueous feed solutions. The AmO2+ generated using the present method under non-complexing pH conditions makes it also suitable for exploring the fundamental chemistry of the higher valent americyl ion. A complexation study using the thus-generated AmO2+ ion with acetate ion supports the concept. [ABSTRACT FROM AUTHOR]

Human serum albumin (HSA) is the most abundant plasma protein, which functions to transport a large range of ligands within the circulation. These interactions have important implications for human health and disease. The primary binding site for CuII ions on HSA is known to be the so-called amino-terminal CuII and NiII binding (ATCUN) motif. However, the number and identity of secondary binding sites is currently not understood. In this study, we harnessed a suite of contemporary electron paramagnetic resonance (EPR) spectroscopy methods to investigate recombinantly produced constructs of HSA bearing single-histidine knockouts, with the aim to characterise its endogenous CuII ion binding sites. [ABSTRACT FROM AUTHOR]

Two-pore domain K+ (K2P) channel activity was previously thought to be controlled primarily via a selectivity filter (SF) gate. However, recent crystal structures of TASK-1 and TASK-2 revealed a lower gate at the cytoplasmic pore entrance. Here, we report functional evidence of such a lower gate in the K2P channel K2P17.1 (TALK-2, TASK-4). We identified compounds (drugs and lipids) and mutations that opened the lower gate allowing the fast modification of pore cysteine residues. Surprisingly, stimuli that directly target the SF gate (i.e., pHe., Rb+ permeation, membrane depolarization) also opened the cytoplasmic gate. Reciprocally, opening of the lower gate reduced the electric work to open the SF via voltage driven ion binding. Therefore, it appears that the SF is so rigidly locked into the TALK-2 protein structure that changes in ion occupancy can pry open a distant lower gate and, vice versa, opening of the lower gate concurrently promote SF gate opening. This concept might extent to other K+ channels that contain two gates (e.g., voltage-gated K+ channels) for which such a positive gate coupling has been suggested, but so far not directly demonstrated. Here, the authors identify a cytoplasmic gate in the K2P channel TALK-2 that is strongly positively-coupled to a second gate made up by the selectivity filter. Thereby, stimuli that converge at either gate open both gates, allowing effective polymodal regulation. [ABSTRACT FROM AUTHOR]

AgBiO3 is reported for the exclusive oxidation of Am3+ → AmO2+ at near-neutral pH conditions. Literature methods of AmO2+ generation are generally two-step processes; i.e., Am3+ → AmO22+ oxidation followed by AmO22+ → AmO2+ reduction. These methods for Am3+ → AmO2+ oxidation use high temperatures (80–100 °C) and/or several reagents, causing the in situ presence of the AmO2+-complex rather than the AmO2+aq ions. This not only interferes with the much-needed Am–Cm selectivity but also limits the use of AmO2+aq in any other experimental study. The single-step Am3+ → AmO2+ oxidation in the present work using AgBiO3 is done at 25 °C in a non-complexing medium at pH ∼4, making it a first-of-its-kind report. Am–Eu and Am–Cm separation in a single contact, with a separation factor >104, was achieved using the present method, which is unprecedented among aqueous feed solutions. The AmO2+ generated using the present method under non-complexing pH conditions makes it also suitable for exploring the fundamental chemistry of the higher valent americyl ion. A complexation study using the thus-generated AmO2+ ion with acetate ion supports the concept. [ABSTRACT FROM AUTHOR]

Energy and environmental issues have increasingly garnered significant attention for sustainable development. Flexible and shape‐stable phase change materials display great potential in regulation of environmental temperature for energy saving and human comfort. Here, inspired by the water absorption behavior of salt‐tolerant animals and plants in salinity environment and the Hofmeister theory, highly stable phase change salogels (PCSGs) are fabricated through in situ polymerization of hydrophilic monomers in molten salt hydrates, which can serve multiple functions including thermal management patches, smart windows, and ice blocking coatings. The gelation principles of the polymer in high ion concentration solution are explored through the density functional theory simulation and verified the feasibility of four types of salt hydrates. The high concentration chaotropic ions strongly interacted with polymer chains and promoted the gelation at low polymer concentrations which derive highly‐stable and ultra‐moisturizing PCSGs with high latent heat (> 200 J g−1). The synergistic adhesion and transparency switching abilities accompanied with phase transition enable their smart thermal management. The study resolves the melting leakage and thermal cycling stability of salt hydrates, and open an avenue to fabricate flexible PCM of low cost, high latent heat, and long‐term durability for energy‐saving, ice‐blocking, and thermal management. [ABSTRACT FROM AUTHOR]

Inadequate osseointegration at the interface is a key factor in orthopedic implant failure. Mechanistically, traditional orthopedic implant interfaces fail to precisely match natural bone regeneration processes in vivo. In this study, a novel biomimetic coating on titanium substrates (DPA‐Co/GFO) through a mussel adhesion‐mediated ion coordination and molecular clicking strategy is engineered. In vivo and in vitro results confirm that the coating exhibits excellent biocompatibility and effectively promotes angiogenesis and osteogenesis. Crucially, the biomimetic coating targets the integrin α2β1 receptor to promote M2 macrophage polarization and achieves a synergistic effect between immunomodulation and vascularized bone regeneration, thereby maximizing osseointegration at the interface. Mechanical push‐out tests reveal that the pull‐out strength in the DPA‐Co/GFO group is markedly greater than that in the control group (79.04 ± 3.20 N vs 31.47 ± 1.87 N, P < 0.01) and even surpasses that in the sham group (79.04 ± 3.20 N vs 63.09 ± 8.52 N, P < 0.01). In summary, the novel biomimetic coating developed in this study precisely matches the natural process of bone regeneration in vivo, enhancing interface‐related osseointegration and showing considerable potential for clinical translation and applications. [ABSTRACT FROM AUTHOR]

The integration of anionic Ti4L6 (L = embonate) cages and π-conjugated coordination cations into ordered structures can produce high-performance nonlinear optical (NLO) materials. More specifically, by employing Ti4L6 cages for assembly with mixed N,N-chelated and P,P-chelated type conjugated organic ligands and Ag+ ions, three cage-based structures have been synthesized and structurally characterized. Among them, an ion pair structure with strong π–π accumulation exhibits a significant third-order NLO response, and an excellent optical limiting effect has been experimentally verified. This work provides a promising material for NLO applications. [ABSTRACT FROM AUTHOR]

The practical application of solid‐state polymer lithium‐metal batteries (LMBs) is plagued by the inferior ionic conductivity of the applied polymer electrolytes (PEs), which is caused by the coupling of ion transport with the motion of polymer segments. Here, solvated molecules based on ionic liquid and lithium salt with strong Li+‐solvent interaction are inserted into an elaborately engineered perfluoropolymer electrolyte via ionic dipole interaction, extensively facilitating Li+ transport and improving mechanical properties. The intensified formation of solvation structures of contact ion pairs and ionic aggregates, as well as the strong electron‐withdrawal properties of the F atoms in perfluoropolymers, give the PE high electrochemical stability and excellent interfacial stability. As a result, Li||Li symmetric cells demonstrate a lifetime of 2500 h and an exceptionally high critical current density above 2.3 mA cm−2, Li||LiFePO4 batteries exhibit consistent cycling for 550 cycles at 10 C, and Li||uncoated LiNi0.8Co0.1Mn0.1O2 cells achieve 1000 cycles at 0.5 C with an average Coulombic efficiency of 98.45 %, one of the best results reported to date based on PEs. Our discovery sheds fresh light on the targeted synergistic regulation of the electro‐chemo‐mechanical properties of PEs to extend the cycle life of LMBs. [ABSTRACT FROM AUTHOR]

The study investigated the structural and dynamical properties of hydrated ion Barium (Ba2+) in aqueous solution using quantum mechanical/molecular mechanical molecular dynamics simulations (QM/MM MD simulation). The primary objective was to assess the performance of the SCAN functional in describing the structure and dynamics of formed Ba2+ hydration shells in aqueous solution. The SCAN/MM MD simulation demonstrated the closest agreement with previously reported experimental data regarding the structural and dynamical properties of hydrated ion Ba2+. Specifically, the Ba2+ and surrounding water molecules distance was determined to be 2.79 Å, with equal distribution of coordination numbers of 8 and 9 in the first hydration shell. Moreover, the stretching frequency of 232.21 cm−1 closely matched the CCSD(T) results. The obtained results from SCAN/MM MD has a better agreement than results from MP2/MM and DKH2 MP2/MM molecular dynamics simulation. These findings underscore the potential of SCAN/MM MD simulation as a promising method for investigating the structural and dynamical properties of hydrated ions. [ABSTRACT FROM AUTHOR]

A proof-of-concept study of the utilization of a single mass spectrometer for qualitative molecular analysis as well as for quantitative metal determination is described. This was performed with an argon microwave plasma as the ion source coupled to an ion trap mass spectrometer. A microwave induced plasma with tuneable power and gas flow rate was loaded with dried nebulized sample solutions. The commercially available plasma torch was slightly modified to allow the introduction of the sample in different regions of the plasma. Using soft settings, organic compounds introduced in the plasma plume could be detected as protonated molecular ions. Under harsher conditions, elemental analysis was demonstrated for several metals. Lead could be determined with a limit of detection of 150 nM. Minor on-the-fly adjustments of the power, flow rate and sampling distance allowed a mild fragmentation of organic compounds. Ionization differences observed were rationalized by emission spectroscopy, and excitation and rotational temperatures were determined. Simultaneous determination of elemental and molecular information was demonstrated for a rubidium–crown-ether complex. The maximum argon gas consumption for these tasks was below 2 L min−1 and the maximal power used was 90 W. [ABSTRACT FROM AUTHOR]

We have successfully synthesized a new Ni(II)‐based coordination polymer (CP) [Ni2(cis‐1,4‐chdc)2(4,4′‐bpy)3(H2O)2] (1); (cis‐1,4‐ H2chdc=cis‐1,4‐cyclohexanedicarboxylic acid and 4,4′‐bpy=4,4′‐bipyridine) employing slow diffusion method in a single pot technique. The connectivity of Ni(II) ions and bridging cis‐1,4‐chdc ligand gives rise to a three‐dimensional (3D) framework with 2‐fold interpenetrated diamondoid topology. Interestingly, the synthesized CP acts as efficient catalyst for electrocatalytic water splitting. The water oxidation activity of compound 1 exhibits Tafel slope equivalent to 361.48 mV.dec−1 for hydrogen evolution reaction (HER) and 353.53 mV.dec−1 for oxygen evolution reaction (OER) in an alkaline medium while almost similar values of Tafel slope for HER and OER equivalent to 287.33 mV.dec−1 and 289.93 mV.dec−1 respectively in acidic medium. Thus, the compound 1 has excellent efficacy in catalyzing HER and OER in acidic as well as alkaline medium, which is ascribed to its distinctive 3D architecture. [ABSTRACT FROM AUTHOR]

The hydrosilylation reactions of dihydrosilylium ion 2, stabilized by coordination of a σ‐donating Ni(0) fragment, has been investigated. Complex 2 with two reactive sites, dihydrosilylium and Ni(0) centers, readily reacts with diphenylacetylene via a selective mono‐hydrosilylation reaction to afford the corresponding Ni(0)‐stabilized (hydro)(vinyl)silylium ion 6. In the case of ethylene, three equivalents of olefin are consumed to give a cationic Ni(II)‐complex 7 featuring a Bu‐Si+‐NiII‐Et moiety with a NHC‐supported Si atom. DFT calculations indicate that the hydrosilylation proceeds by a classical (Chalk‐Harrod type) mechanism with the assistance of NHC ligand moving between Si and Ni centers according to their stabilization requirements. [ABSTRACT FROM AUTHOR]

Pseudocontact shifts (PCS) generated by paramagnetic lanthanide ions deliver powerful restraints for protein structure analysis by NMR spectroscopy. We present a new lanthanide tag that generates different PCSs than that of a related tag, which differs in structure by a single oxygen atom. It is highly reactive towards cysteine and performs well in turn-on luminescence and in EPR spectroscopy. [ABSTRACT FROM AUTHOR]

Light and pH dual-responsive ion transporters offer better applicability for cancer due to higher tunability and low cytotoxicity. Herein, we demonstrate the development of pH-responsive β-carboline-based ionophores and photocleavable-linker appended β-carboline-based proionophores to facilitate the controlled transport of Cl− across membranes, leading to apoptotic and autophagic cancer cell death. [ABSTRACT FROM AUTHOR]

Triphenylamine (TPA) and N‐heterotriangulene (N‐HTA) scaffolds with up to three oligophenyl extensions are investigated by electrospray ionization (tandem) mass spectrometry (ESI‐[MS/]MS). Due to their low oxidation potentials, all molecules readily form radical cations in the electrospray process. The energy‐resolved collision‐induced dissociation behaviour of the molecular ions is contrasted to that of the silver(I) adducts. Complexation with Ag(I) leads to the expected [1:1] and [2:1] complexes (MAg+ and M2Ag+); however, even [1:2] complexes (MAg22+) can be detected for molecules with two and three large π‐expansions to allow stabilization of two charges. The TPA scaffolds decompose only at high collision energies through the loss of peripheral tert‐butyl groups. A general mechanism for this is proposed commencing with a methyl loss and followed by the release of isobutene and butyl radical moieties. The N‐HTA‐based scaffolds are considerably less stable and molecular ions fragment at low collision energies. This is caused by the facile loss of methyl radicals from the dimethylmethylene‐bridged triangulene core. In contrast, complexation with Ag+ leads to a dramatic stabilization. Most interestingly, dissociation eventually proceeds via the loss of neutral AgCH3, which is indicative of strong bidentate, tweezer‐like bonding of Ag+ to the molecules. [ABSTRACT FROM AUTHOR]

Recent developments in ultrashort and intense laser systems have enabled the generation of short and brilliant proton sources, which are valuable for studying plasmas under extreme conditions in high-energy-density physics. However, developing sensors for the energy selection, focusing, transport, and detection of these sources remains challenging. This work presents a novel and simple design for an isochronous magnetic selector capable of angular and energy selection of proton sources, significantly reducing temporal spread compared to the current state of the art. The isochronous selector separates the beam based on ion energy, making it a potential component in new energy spectrum sensors for ions. Analytical estimations and Monte Carlo simulations validate the proposed configuration. Due to its low temporal spread, this selector is also useful for studying extreme states of matter, such as proton stopping power in warm dense matter, where short plasma stagnation time (<100 ps) is a critical factor. The proposed selector can also be employed at higher proton energies, achieving final time spreads of a few picoseconds. This has important implications for sensing technologies in the study of coherent energy deposition in biology and medical physics. [ABSTRACT FROM AUTHOR]

Electrical signaling is essential for all fast processes in biology, but its molecular mechanisms have been uncertain. This review article focuses on studies of bacterial sodium channels in order to home in on the essential molecular and chemical mechanisms underlying transmembrane ion conductance and voltage-dependent gating without the overlay of complex protein interactions and regulatory mechanisms in mammalian sodium channels. This minimalist approach has yielded a nearly complete picture of sodium channel function at the atomic level that are mostly conserved in mammalian sodium channels, including sodium selectivity and conductance, voltage sensing and activation, electromechanical coupling to pore opening and closing, slow inactivation, and pathogenic dysfunction in a debilitating channelopathy. Future studies of nature's simplest sodium channels may continue to yield key insights into the fundamental molecular and chemical principles of their function and further elucidate the chemical basis of electrical signaling. [Display omitted] In this review, Catterall et al. describe how electrical signals are generated in excitable cells by voltage-gated sodium channels. The authors highlight fundamental molecular and chemical mechanisms that have arisen in evolution that are crucial to improve our understanding of sodium channel diseases and to develop improved therapies. [ABSTRACT FROM AUTHOR]

Understanding molecular state evolution is central to many disciplines, including molecular dynamics, precision measurement, and molecule-based quantum technology. Details of this evolution are obscured when observing a statistical ensemble of molecules. Here, we report real-time observations of thermal radiation–driven transitions between individual states (“jumps”) of a single molecule. We reversed these jumps through microwave-driven transitions, which resulted in a 20-fold improvement in the time the molecule dwells in a chosen state. The measured transition rates showed anisotropy in the thermal environment, pointing to the possibility of using single molecules as in situ probes for the strengths of ambient fields. Our approaches for state detection and manipulation could apply to a wide range of species, facilitating their uses in fields including quantum science, molecular physics, and ion-neutral chemistry. [ABSTRACT FROM AUTHOR]

[Display omitted] Urea electrolysis is an appealing topic for hydrogen production due to its ability to extract hydrogen at a lower potential. However, it is plagued by sluggish kinetics and noble-metal catalyst requirements. Herein, we developed nickel-iron-layered double hydroxide (NiFe-LDH) nanolayers with abundant oxygen vacancies (O V) via synergistically etching nickel foam with Fe3+ and Cl- ions, enabling the efficient conversion of urea into H 2 and N 2. The synthesized O V -NiFe-LDH exhibits a lower potential (1.30 vs. reversible hydrogen electrode, RHE) for achieving 10 mA cm−2 in the urea oxidation reaction (UOR), surpassing most recently reported Ni-based electrodes. O V provides favorable conductivity and a large surface area, which results in a 4.1-fold in electron transport and a 5.1-fold increase in catalyst reactive sites. Density Functional Theory (DFT) calculations indicate that O V can lower the adsorption energy of urea, and enhance the bonding strength of *CONHNH, giving rise to improved UOR. This study provides a viable path toward economical and efficient production of high-purity hydrogen. [ABSTRACT FROM AUTHOR]

Reduction of hexaazatrinaphthylene (HAN) and its hexamethyl derivative with [Cp*2Sm(THF)2] or [Cp*2Yb(OEt2)] produces [(Cp*2Ln)3(R6HAN)] (Ln = Sm, Yb; R = H, Me), where the heterocyclic ligand forms as a trianion. The magnetism and electronic structure of these compounds reflect unusual multiconfigurational character within the reduced ligand but not the lanthanide ions. [ABSTRACT FROM AUTHOR]

Exploring functional substrates for single‐atom electrocatalysts and precisely modulating their electronic microenvironments are of significant importance for sulfur redox chemistry in lithium‐sulfur batteries (LSBs) with unsatisfactory shuttle effects and sluggish redox kinetic. Herein, the electronic microenvironment of atomic ion (Fe) is rationally unraveled and modulated by nitrogen (N)‐bridged ligands that are engineered by metallic vacancies in MoB spontaneously trapping atomic Fe by fluorine‐free organic molten salt in situ etching and self‐reduction strategy. Intriguingly, these atomic Fe can be coordinated with adjacent in‐plane boron (B), lattice oxygen (O) and axial bridged N‐doped carbon (NC) to construct the distinctive Fe configuration (FeB4‐O‐NC‐MoB). Theorical calculations and experimental investigations unveil the electronic microenvironment of Fe disturbed from axial bridged N to construct octahedra configuration that can reinforce adsorption energy and lower energy barrier by Fe‐S and N‐Li bonds to suppress shuttle effect and expedite bidirectional redox kinetics. Thus, FeB4‐O‐NC‐MoB modified separator in LSBs delivers impressive reversible capacities (765 mAh g−1 at 0.5 C after 500 cycles and 541.9 mAh g−1 at 2 C after 5000 cycles). This work affords a feasible strategy for modulating electronic microenvironment by manipulating coordination configuration of single‐atom electrocatalyst to boost the bilateral sulfur redox chemistry. [ABSTRACT FROM AUTHOR]

The stereodivergent synthesis of all four stereoisomers of diethyl 4-hydroxyphosphopipecolate from the commercial chiral building block ethyl (R)-4-cyano-3-hydroxybutanoate is described. Key steps in the synthesis of the target compounds involve the triethyl phosphite nucleophilic addition to chiral N -acyliminium ion easily obtained from (R)-4-hydroxypiperidin-2-one, giving diethyl (2 R ,4 R)- and (2 S ,4 R)-4-hydroxyphosphopipecolate diastereoisomers, easily separable by column chromatography followed by the 4-hydroxy epimerization through a sequential oxidation and highly diastereoselective reduction strategy, affording the diethyl (2 R ,4 S)- and (2 S ,4 S)-4-hydroxyphosphopipecolate, respectively, consistent with our recently found results. All synthesized compounds were thoroughly characterized. [ABSTRACT FROM AUTHOR]

Rubidium (Rb), a rare and precious metal, is widely used in high‐tech fields. In this work the structural advantages of mordenite (MOR) and group affinity of phenolic hydroxyl polymers (poly (styrene‐4‐hydroxystyrene) (P(S‐co‐VPh)) are combined to prepare MOR/P(S‐co‐VPh) nanofiber composite membranes with high selectivity and adsorption specificity for Rb+ by electrospinning. The test results show that MOR is successfully anchored on the nanofiber substrate and maintained its complete crystal structure. Adsorption experiments show that the adsorption capacity of Rb+ increases with the increase of MOR content, and pH = 9.0, T = 25°C are the best adsorption conditions. K+ shows the most obvious interference with the adsorption capacity decreased from 60.03 to 39.33 mg/g. The adsorption process follows with the Langmuir isothermal model and pseudo‐second‐order kinetic equation. The chemical adsorption based on the coordination reaction is the control step, and the intraparticle diffusion also has an important effect on the adsorption rate. The recycling test indicates that the prepared nanofiber composite membrane not only has efficient adsorption of Rb+, but also exhibits excellent regeneration and stability, which helps to achieve its widespread application and long‐term operation in harsh environments. [ABSTRACT FROM AUTHOR]

Connexin hemichannels were identified as the first members of the eukaryotic large-pore channel family that mediate permeation of both atomic ions and small molecules between the intracellular and extracellular environments. The conventional view is that their pore is a large passive conduit through which both ions and molecules diffuse in a similar manner. In stark contrast to this notion, we demonstrate that the permeation of ions and of molecules in connexin hemichannels can be uncoupled and differentially regulated. We find that human connexin mutations that produce pathologies and were previously thought to be loss-of-function mutations due to the lack of ionic currents are still capable of mediating the passive transport of molecules with kinetics close to those of wild-type channels. This molecular transport displays saturability in the micromolar range, selectivity, and competitive inhibition, properties that are tuned by specific interactions between the permeating molecules and the N-terminal domain that lies within the pore--a general feature of large-pore channels. We propose that connexin hemichannels and, likely, other large-pore channels, are hybrid channel/transporter-like proteins that might switch between these two modes to promote selective ion conduction or autocrine/paracrine molecular signaling in health and disease processes. [ABSTRACT FROM AUTHOR]

We present a practical scheme for the efficient preparation of laser–cooled 43 Ca + ions in an ion trap. Our approach integrates two well-established methods: isotope-selective photoionization and isotope-specific parametric excitation. Drawing inspiration from the individual merits of each method, we have successfully integrated these techniques to prepare extended chains of 43 Ca + ions, overcoming the challenge posed by their low natural abundance of 0.135% in a natural source. Furthermore, we explore the subtleties of our scheme, focusing on the influence of different factors on the purification process. Our investigation contributes to a broader understanding of the technique and highlights the adaptability of established methods in addressing specific isotopic challenges. [ABSTRACT FROM AUTHOR]

Traditional luminescent materials commonly exhibit single‐duration emissions and single‐timed emissions with limited emission peaks. Developing a material with multicolor, variable temporal, and multimodal luminescence is a significant challenge. Self‐reduction phosphors have attracted considerable interest for their distinctive properties and versatile applications. Distinguished by their rigid structure and exceptional purity, offer a safer alternative to conventional reduction methods using hazardous gases H2/CO/N2. However, synthesizing these phosphors with precise control over self‐reduction and defect regulation is complex. Therefore, innovative structures and substrates are essential to address these challenges. This review discusses the latest developments in phosphors doped with ions such as Eu3+, Mn4+, Ce4+, and Yb3+, examining the origins and advancements in self‐reduction. It covers classifications, mechanisms, defects, and applications, with an emphasis on techniques for controlled self‐reduction through structural and charge transfer modifications. This work aims to provide valuable insights to facilitate further research and innovation endeavors. [ABSTRACT FROM AUTHOR]

Biological ion channels are renowned for their exceptional ion transport selectivity and adaptability to environmental changes, posing a significant challenge for synthetic mimicry. Herein, an innovative covalent–organic‐framework membrane featuring aligned benzothiadiazole units within its oriented 1D nanochannels is reported. These densely arrayed dipolar benzothiadiazole units enhance selective ion adsorption and facilitate membrane charge regulation. Consequently, the membrane can dynamically adjust its permselectivity toward ions, transitioning seamlessly between cation‐selective, ambipolar, and anion‐selective states. This versatility affects both the type of ions transported and the transport efficiency, supporting reversible and controlled membrane operation, as illustrated by the capacity to regulate the magnitude and direction of osmotic power. When interacting with multivalent anions, highly negatively charged channels of the membrane exhibit outstanding cation permselectivity and conductivity. Specifically, upon exposure to PO43− ions, the membrane achieves a remarkable osmotic power of 155 W m−2 and an energy conversion efficiency of 46.1% under salinity gradients of 0.5 and 0.01 m NaCl. Notably, introducing multivalent cations can reverse the polarity of the membrane. This work underscores the potential of exploiting ion‐dipolar interactions for the development of adaptive, ion‐selective membranes with promising applications in electrochemical sensing, energy conversion, and more. [ABSTRACT FROM AUTHOR]

The ongoing evolution of two-dimensional (2D) material-based membranes has prompted the realization of mass separations at the 1-nm scale due to their well-defined selective nano- and subnanochannels. Strategic membrane functionalization is further found to be key to augmenting channel accuracy and efficiency in distinguishing ions, gases and molecules within this range and is thus trending as a research focus in energy-, resource-, environment- and pharmaceutical-related applications. In this review, we present the fundamentals underpinning functionalized 2D membranes in various separations, elucidating the critical "method–interaction–property" relationship. Starting with an introduction to various functionalization strategies, we focus our discussion on functionalization-induced channel-species interactions and reveal how they shape the transport- and operation-related features of the membrane in different scenarios. We also highlight the limitations and challenges of current functionalized 2D membranes and outline the necessary breakthroughs needed to apply them as reliable and high-performance separation units across industries in the future. [ABSTRACT FROM AUTHOR]

We have developed a method for ring contraction of N−H piperidines using oxidative rearrangement with PhI(OAc)2. The reaction forms iminium ion intermediates that are effectively trapped by nucleophiles (e. g. NaBH4, H2O) yielding the corresponding pyrrolidine derivatives. Additionally, we propose an ionic mechanism supported by experiments and density‐functional theory calculations. [ABSTRACT FROM AUTHOR]

Aptamers are oligonucleotides with antibody-like binding function, selected from large combinatorial libraries. In this study, we modified a DNA aptamer library with N-hydroxysuccinimide esters, enabling covalent conjugation with cognate proteins. We selected for the ability to bind to mouse monoclonal antibodies, resulting in the isolation of two distinct covalent binding motifs. The covalent aptamers are specific for the Fc region of mouse monoclonal IgG1 and are cross-reactive with mouse IgG2a and other IgGs. Investigation into the covalent conjugation of the aptamers revealed a dependence on micromolar concentrations of Cu2+ ions which can be explained by residual catalyst remaining after modification of the aptamer library. The aptamers were successfully used as adapters in the formation of antibody-oligonucleotide conjugates (AOCs) for use in detection of HIV protein p24 and super-resolution imaging of actin. This work introduces a new method for the site-specific modification of native monoclonal antibodies and may be useful in applications requiring AOCs or other antibody conjugates. Site-specific conjugation of oligonucleotides and native proteins remains challenging. Here, the authors select covalent DNA aptamers from a library modified with N-hydroxysuccinimide esters, and show their application in the formation of antibody–oligonucleotide conjugates for protein detection. [ABSTRACT FROM AUTHOR]