Weak Interactions Research Articles

Room‐temperature Magnetocapacitance Spanning 97K Hysteresis in Molecular Material

AbstractMagnetic capacitor, as a new type of device, has broad application prospects in fields such as magnetic field sensing, magnetic storage, magnetic field control, power electronics and so on. Traditional magnetic capacitors are mostly assembled by magnetic and capacitive materials. Magnetic capacitor made of a single material with intrinsic properties is very rare. This intrinsic property is magnetocapacitance (MC). The studies on MC effect have mainly focused on metal oxides so far. No study was reported in molecular materials. Herein, two complexes: (CETAB)2[CuCl4] (1) and (CETAB)2[CuBr4] (2) (CETAB=(2‐chloroethyl)trimethylammonium) are reported. There exist strong H−Br and Br−Br interactions and other weak interactions in complex 2, so the phase transition energy barrier is high, resulting in the widest thermal hysteresis loop on a molecular level to date. Furthermore, complexes 1 and 2 show large MC parameters of 0.247 and 1.614, respectively, which is the first time to observe MC effect in molecular material.

A Polymeric Hole Transporter with Dual-Interfacial Interactions Enables 25%-Efficiency Blade-Coated Perovskite Solar Cells.

Self-assembly monolayer (SAM) hole transporters, consisting of anchoring, spacer, and terminal groups, have played a significant role in the development of inverted perovskite solar cells (PSCs). However, the weak interaction between perovskite and hydrophobic terminal group of SAMs limits surface wettability and interface stability. To address this issue, two novel hole transporters (named DBPP and Poly-DBPP) with centrosymmetric biphosphonic acid groups are developed. Unlike conventional SAM hole transporters, the biphosphonic acid groups in DBPP and Poly-DBPP can anchor to the underlying conductive substrate and interact with the perovskite layer simultaneously, improving surface wettability and suppressing interface recombination. Furthermore, compared to the small-molecular DBPP, Poly-DBPP exhibits higher conductance and excellent uniformity. This translates to a remarkable power conversion efficiency of 25.1% for blade-coated PSCs and 22.0% for large-area modules, respectively. Additionally, the PSCs based on Poly-DBPP demonstrate impressive operational stability, retaining 92% of their initial PCE after 1,600 h of light soaking. This work presents a promising strategy for designing multifunctional hole transporters, paving the way for highly efficient and stable PSCs.

Quenching Rate Constants of Lewis Base-Boryl Radical by Substrates: a Laser Flash Photolysis Study.

The advanced strategy using Lewis base-boryl radicals (LBRs) has recently been proposed for the addition of alkyl substituents to the full-carbon quaternary center of an organic molecule. However, as the rate-determining step in the whole route, reaction rate constants of LBRs with substrates are extremely lacking. In this paper, 4-dimethylaminopyridine (DMAP)-BH2• was selected as a representative of LBRs, and its reactions with six monochloro-substituted substrates, including three methyl chlorobenzoates and three chlorinated acetanilides were studied in experiments and theoretical calculations. The bimolecular reaction rate constants, kq, were determined using laser flash photolysis approach. By comparing activation energies along the two addition pathways, we have clarified the rate-determining step as the attacking to carbonyl oxygen instead of chlorine atom. Furthermore, noncovalent interaction (NCI) analyses on these substrates indicate that weak interactions, such as hydrogen-bonding and van der Waals interactions, have significant influence on the reactivity of these substrates. Our study provides concrete clues to extend this synthetic strategy.

Hydration behavior of L-proline in the presence of mono, bis, tris-(2-hydroxyethyl) ammonium acetate protic ionic liquids: Thermophysical properties

The hydration behavior of amino acids, essential for biological macromolecules, is influenced by ammonium biomaterials. The protic ionic liquids (PILs) are gaining attention in the food and pharmaceutical industries due to their nontoxicity and adjustable properties. Thus, study of the amino acids, such as L-proline, in the presence of PILs is crucial for understanding their hydration behavior. In this work, the effect of PILs, including mono, bis, tris (2-hydroxyethyl)ammonium acetate protic ionic liquids that might be naturally produced in human body, on L-proline hydration behavior was studied using COSMO calculations and thermophysical measurements. Measurements were the density, speed of sound, viscosity, and refractive index data of the solutions (L-proline + PILs + water) at various PIL concentrations at temperatures (298.15 to 318.15) K and under atmospheric pressure. The study indicates L-proline has weaker interactions with water compared to PILs ([2-HEA][Ac], [bis-2-HEA][Ac], and [tris-2-HEA][Ac]) due to its compact structure and lower negative dielectric energy. PILs interact more strongly with water through hydrogen bonding. Increasing temperature affects L-proline’s hydration layer, releasing more water molecules compared to PIL solutions. This effect is more pronounced with [tris-2-HEA][Ac], likely due to its larger size and complex structure. While L-proline promotes an ordered water structure, PILs can disrupt this by rearranging water molecules and forming their own hydrogen bonds.

Refined Protein-Sugar Interactions in the Martini Force Field.

Sugar molecules play important roles as mediators of biomolecular interactions in cellular functions, disease, and infections. Molecular dynamics simulations are an indispensable tool to explore these interactions at the molecular level. The large time and length scales involved frequently necessitate the use of coarse-grained representations, which heavily depend on the parametrization of sugar-protein interactions. Here, we adjust the sugar-protein interactions in the widely used Martini 2.2 force field to reproduce the experimental osmotic second virial coefficients between sugars and proteins. In simulations of two model proteins in glucose solutions with adjusted force field parameters, we observe weak protein-sugar interactions. The sugar molecules are thus acting mainly as crowding agents, in agreement with experimental measurements. The procedure to fine-tune sugar-protein interactions is generally applicable and could also prove useful for atomistic force fields.

Crystallization Control of Anionic Thiacalixarenes on Silicon Surface Coated with Cationic Poly(ethyleneimine).

Surface modification of solid substrates with organic molecules and polyelectrolytes is a promising strategy toward advanced soft materials due to the control of molecular arrangement and supramolecular organization; however, understanding the nature of interactions within the assembly is challenging. Here a facile approach to the control of the architecture of calixarene macrocycles on soft surfaces is presented through the interplay of weak interactions involving a solid silicon substrate, a cationic polyelectrolyte layer, and anionic sulfonatothiacalix[4]arene (STCA). Topological analysis of atomic force microscopy (AFM) images of STCA on silicon, as well as silicon wafers modified with neutral polyethylenimine (PEI) and cationic PEI-H+, indicates different surface morphology and assembly behavior of STCA on such substrates. Drop-casting a calixarene solution onto silicon induces the formation of chaotically oriented needle crystals. When there is globular PEI, a nucleation point for the STCA crystals is formed on the polyelectrolyte surface, which grows into rosette structures. In contrast, protonated PEI with a chain-like structure alters the self-organization of STCA on silicon surfaces, leading to a dense uniform fiber-like network. Density functional theory modeling of the system components' self-assembly reveals thermodynamically favorable face-to-face antiparallel aggregation of STCA monomers and contribution of H-bonding into PEI(PEI-H+)-STCA and Si-STCA association.

Metal Ion Sensing by Tetraloop-like RNA Fragment: Role of Compact Intermediates with Non-Native Metal Ion-RNA Inner-Shell Contacts.

Divalent metal ions influence the folding and function of ribonucleic acid (RNA) in the cells. The mechanism of how RNA structural elements in riboswitches sense specific metal ions is unclear. RNA interacts with ions through two distinct binding modes: direct interaction between the ion and RNA (inner-shell (IS) coordination) and indirect interaction between the ion and RNA mediated through water molecules (outer-shell (OS) coordination). To understand how RNA senses metal ions such as Mg2+ and Ca2+, we studied the folding of a small RNA segment from the Mg2+ sensing M-Box riboswitch using computer simulations. This RNA segment has the characteristics of a GNRA tetraloop motif and interestingly requires the binding of a single Mg2+ ion. The folding free energy surface of this simple tetraloop system is multidimensional, with a population of multiple intermediates where the tetraloop and cation interact through IS and OS coordination. The partially folded compact tetraloop intermediates form multiple non-native IS contacts with the metal ion. Thermal fluctuations should break these strong non-native IS contacts so that the tetraloop can fold to the native state, resulting in higher folding free energy barriers. Ca2+ undergoes rapid OS to IS transitions and vice versa due to its lower charge density than Mg2+. However, the ability of Ca2+ to stabilize the native tetraloop state is weaker, as it could not hold the loop-closing nucleotides together due to its weaker interactions with the nucleotides. These insights are critical to understanding the specific ion sensing mechanisms in riboswitches, and the predictions are amenable for verification by nuclear magnetic resonance (NMR) experiments.

Modulator-Directed Counterintuitive Catenation Control for Crafting Highly Porous and Robust Metal-Organic Frameworks with Record High SO2 Uptake Capacity.

Sulfur dioxide (SO2) is an important industrial feedstock that can be directly utilized or catalytically transformed to value-added chemicals such as sulfuric acid. The development of regenerable porous sorbents for the highly efficient storage and energy-minimal release of toxic SO2 operating under ambient conditions has attracted growing interest. Herein, we report the topology-guided construction of highly porous acs-type metal-organic frameworks (MOFs) through a counterintuitive modulator-directed catenation control approach. In contrast to the conventional modulator facilitated coordination competition that favors the thermodynamic catenated phase, we show that the elevation of modulator concentration can promote the formation of the noncatenated phase probably through a sublattice dissolution pathway. The assembly of a custom-designed trigonal prismatic triptycene-quinoxaline linker and trinuclear Fe3O cluster affords either the threefold catenated SJTU-219 or noncatenated SJTU-220 with desired acs net. Impressively, the synthetic approach is applicable to various metal ions, including Al3+, V3+, and even Ti4+. The noncatenated SJTU-220 exhibits an extraordinary SO2 sorption capacity of 29.6 mmol g-1 at 298 K and 1 bar, surpassing all reported solid sorbents. The uptake capacity can be further raised to 35.6 mmol g-1 via the replacement of Fe3+ with kinetically more inert Cr3+, resulting in a staggering ∼329-fold volume reduction compared with free ideal SO2 gas. Computational simulations suggest that unique Fe3+···S(SO2) interactions dominate the SO2 seeding process, facilitating the efficient packing of SO2 molecules in the large channels. Besides, the exceptionally low uptake at the low pressure region implies global weak framework-SO2 interactions, which offer great potential for practically implementing an "easy-on/easy-off" SO2 delivery system.

Topological amplitudes of charmed baryon decays in the SU(3)F limit

Charmed baryon decay plays an important role in studying the weak and strong interactions. Topological diagram is an intuitive tool for analyzing the dynamics of heavy hadron decays. In this work, we investigate the topological diagrams of charmed baryon antitriplet (Bc3¯) decays into a light baryon octet (B8) and a light meson (M). A one-to-one mapping between the topological diagram and the invariant tensor is established. The topological diagrams of the Bc3¯→B8SM modes (where B8S and B8A are the q1↔q2 symmetric and antisymmetric octets) and the diagrams with a quark loop are presented for the first time. The completeness of topologies is confirmed by permutation. The linear relations of topologies are obtained by deriving the relation between the topological amplitudes constructed by the third- and second-rank octet tensors. It is found the topologies contributing to the Bc3¯→B8SM modes can be determined by the topologies contributing to the Bc3¯→B8AM modes, and vice versa. The equations of SU(3) irreducible amplitudes decomposed by topologies are derived through two different intermediate amplitudes. However, the inverse solution does not exist since the number of topologies exceeds number of SU(3) irreducible amplitudes. Applying this framework to the Standard Model, it is found there are thirteen independent SU(3) irreducible amplitudes contributing to the Bc3¯→B8M decays. Among these, four amplitudes associated with three-dimensional operators are significant for CP asymmetries. Considering the suppressions due to small Cabibbo-Kobayashi-Maskawa matrix elements and the Körner-Pati-Woo theorem, the branching fractions of charmed baryon decays are dominated by five SU(3) irreducible amplitudes in the SU(3)F limit. Quark-loop diagrams could enhance the U-spin breaking effects and increase the branching fraction difference of two decay channels. Systematic measurements of branching fractions of the singly Cabibbo-suppressed modes could help identify promising channels for searching for CP asymmetries in the charmed baryon sector. Published by the American Physical Society 2024

Assessing weak interaction and threshold effects of the trophic field overlap index on the relationship between species uniqueness and centrality in food webs

Assessing weak interaction and threshold effects of the trophic field overlap index on the relationship between species uniqueness and centrality in food webs

Record-Breaking H2S Capture and ppm-Level Sensing with a Chemically Stable Porous Organic Cage.

The first experimental investigation of a porous organic cage (POC) for the challenging task of H2S capture is reported. The N-containing cage molecular material, a tertiary amine POC (6FT-RCC3), demonstrates the highest H2S (hydrogen sulfide) capture (record capacity) for a porous material at room temperature and atmospheric pressure (20.6mmol H2S g-1; 25 H2S molecules per cage) combined with excellent reversibility for at least five adsorption-desorption cycles. In situ FTIR spectroscopy, solid-state 13C, and 15N CP MAS NMR spectroscopy experiments are applied to investigate the adsorption mechanism, identifying relatively weak interactions via hydrogen bonding. In addition, the fluorescence performances of this POC material are evaluated for the detection and sensing of H2S, where a clear H2S selectivity is observed over other gases. Remarkably, the limit of detection (LOD) is calculated to be 0.13mm (≈4.43ppm) in a tetrahydrofuran (THF) solution of H2S.

In Situ Formed Continuous and Dense Inorganic Borate-Based SEI for High-Performance Li-Metal Batteries.

The practical application of lithium metal batteries (LMBs) is largely hindered by the notorious lithium dendrite growth, low cycle efficiency associated with insufficient electrode-electrolyte interphase dynamics, and electrolyte combustion. Here, an advanced electrolyte using a combination of three kinds of salts dissolved in carbonate-based solvents is developed. The salt anions dominate a primary solvation sheath, resulting in weak interaction between Li+ and the solvents, as well as the in situ formation of an inorganic-rich bilayer solid electrolyte interface (SEI). The designed electrolyte enables high cycle stability in LMBs with a high-loading NMC cathode (approximately 20mg cm-2), exhibiting 89.89% capacity retention after 200 cycles with the cutoff voltage of 4.5V. Cryo-TEM characterization and density-functional theory (DFT) calculations reveal that the borate-based bilayer SEI, characterized by an exceptional dense structure, effectively suppresses lithium dendrite growth, and certify the crucial role of inorganic component continuity and density within the SEI, which surpasses the absorption and migration energy barrier in terms of significance. This profound understanding of SEI structure holds great potential for advancing the development of high-stable LMBs and can be expanded to other battery system.

Regulating Interface Dipole Interaction between Ethers and Active Species toward Highly Stable Li-SPAN Batteries.

Sulfurized polyacrylonitrile (SPAN) is recognized as a promising organic cathode for long-lifespan lithium metal batteries. Nevertheless, the irreversible cleavage/formation of multiple sulfur-sulfur (S-S) bonds of SPAN within conventional ether-based electrolytes results in loss of active S species, severe capacity fading and shuttle effects. Herein, we propose a new electrolyte based on dipropyl ether (PE) solvent for Li-SPAN batteries. Benefiting from the particular chain-coordination structure and weak dipole interactions with Li+ and active species, the resulting electrolyte not only achieves low desolvation energy barrier and high Li+ transference number, but also displays stable electrolyte-electrode interface (EEI). Consequently, the full cells utilizing this electrolyte exhibit good cyclability, outstanding capacity retention and superior extreme-temperature (-50°C to 50 °C) performance. Furthermore, the Ah-scale pouch cell with lean electrolyte (2.5 g Ah-1) achieves record cycle stability with 96.5% capacity retention after 75 cycles, which deliver an initial specific energy density of 150 Wh kg-1 (based on the weight of the entire cell). Impressively, this strategy demonstrates universality in a series of organic electrodes employing with PE-based electrolytes. This work highlights the strategy for modulating the dipole interaction at EEI for long-lifespan Li-organic batteries at extreme conditions.

Regulating Interface Dipole Interaction between Ethers and Active Species toward Highly Stable Li‐SPAN Batteries

Sulfurized polyacrylonitrile (SPAN) is recognized as a promising organic cathode for long‐lifespan lithium metal batteries. Nevertheless, the irreversible cleavage/formation of multiple sulfur‐sulfur (S‐S) bonds of SPAN within conventional ether‐based electrolytes results in loss of active S species, severe capacity fading and shuttle effects. Herein, we propose a new electrolyte based on dipropyl ether (PE) solvent for Li‐SPAN batteries. Benefiting from the particular chain‐coordination structure and weak dipole interactions with Li+ and active species, the resulting electrolyte not only achieves low desolvation energy barrier and high Li+ transference number, but also displays stable electrolyte‐electrode interface (EEI). Consequently, the full cells utilizing this electrolyte exhibit good cyclability, outstanding capacity retention and superior extreme‐temperature (‐50°C to 50 °C) performance. Furthermore, the Ah‐scale pouch cell with lean electrolyte (2.5 g Ah‐1) achieves record cycle stability with 96.5% capacity retention after 75 cycles, which deliver an initial specific energy density of 150 Wh kg‐1 (based on the weight of the entire cell). Impressively, this strategy demonstrates universality in a series of organic electrodes employing with PE‐based electrolytes. This work highlights the strategy for modulating the dipole interaction at EEI for long‐lifespan Li‐organic batteries at extreme conditions.

Studies of Parity Violation in Atoms

AbstractStudies of the effects of the weak interaction in atomic systems provide tests of the Standard Model of particle physics, and explore physics scenarios beyond the Standard Model. In addition, these studies can offer valuable insights into low‐energy nuclear physics. An overview of the field of atomic parity violation is provided, and implications to nuclear and particle physics and ongoing experimental efforts are discussed. Furthermore, the plans for precision measurements of the signatures of the weak interaction in atomic ytterbium are discussed.

Thieno[3,2-b]pyridine: Attractive scaffold for highly selective inhibitors of underexplored protein kinases with variable binding mode.

Protein kinases are key regulators of numerous biological processes and aberrant kinase activity can cause various diseases, particularly cancer. Herein, we report the identification of new series of highly selective kinase inhibitors based on the thieno[3,2-b]pyridine scaffold. The weak interaction of the thieno[3,2-b]pyridine core with the kinase hinge region allows for profoundly different binding modes all of which maintain high kinome-wide selectivity, as illustrated by the isomers MU1464 and MU1668. Thus, this core structure provides a template of ATP-competitive but not ATP-mimetic inhibitors that are anchored at the kinase back pocket. Mapping the chemical space around the central thieno[3,2-b]pyridine pharmacophore afforded highly selective inhibitors of the kinase Haspin, exemplified by the compound MU1920 that fulfils criteria for a quality chemical probe and is suitable for use in in vivo applications. However, despite the role of Haspin in mitosis, the inhibition of Haspin alone was not sufficient to elicit cytotoxic effect in cancer cells. The thieno[3,2-b]pyridine scaffold can be used in a broader context, as a basis of inhibitors targeting other underexplored protein kinases, such as CDKLs.

Thieno[3,2‐b]pyridine: Attractive scaffold for highly selective inhibitors of underexplored protein kinases with variable binding mode

Protein kinases are key regulators of numerous biological processes and aberrant kinase activity can cause various diseases, particularly cancer. Herein, we report the identification of new series of highly selective kinase inhibitors based on the thieno[3,2‐b]pyridine scaffold. The weak interaction of the thieno[3,2‐b]pyridine core with the kinase hinge region allows for profoundly different binding modes all of which maintain high kinome‐wide selectivity, as illustrated by the isomers MU1464 and MU1668. Thus, this core structure provides a template of ATP‐competitive but not ATP‐mimetic inhibitors that are anchored at the kinase back pocket. Mapping the chemical space around the central thieno[3,2‐b]pyridine pharmacophore afforded highly selective inhibitors of the kinase Haspin, exemplified by the compound MU1920 that fulfils criteria for a quality chemical probe and is suitable for use in in vivo applications. However, despite the role of Haspin in mitosis, the inhibition of Haspin alone was not sufficient to elicit cytotoxic effect in cancer cells. The thieno[3,2‐b]pyridine scaffold can be used in a broader context, as a basis of inhibitors targeting other underexplored protein kinases, such as CDKLs.

Transfer of solitons and half-vortex solitons via adiabatic passage

We show that the transfer of matter-wave solitons and half-vortex solitons in a spin-orbit coupled Bose-Einstein condensate between two (or more) arbitrarily chosen sites of an optical lattice can be implemented using the adiabatic passage. The underlying linear Hamiltonian has a flat band in its spectrum, so that even sufficiently weak interatomic interactions can sustain well-localized Wannier solitons which are involved in the transfer process. The adiabatic passage is assisted by properly chosen spatial and temporal modulations of the Rabi frequency. Within the framework of a few-mode approximation, the mechanism is enabled by a dark state created by coupling the initial and target low-energy solitons with a high-energy extended Bloch state, like in the conventional stimulated Raman adiabatic passage used for the coherent control of quantum states. In real space, however, the atomic transfer between initial and target states is sustained by the current carried by the extended Bloch state, which remains populated during the whole process. The full description of the transfer is provided by the Gross-Pitaevskii equation. Protocols for the adiabatic passage are described for one- and two-dimensional optical lattices, as well as for splitting and subsequent transfer of an initial wave packet simultaneously to two different target locations. Published by the American Physical Society 2024

Enhancing stability of cationic palladium complexes with hemilabile 2-benzyl oxazoline ligands: Structural insights and catalytic implications

This article describes the synthesis and characterization of Pd cationic complexes incorporating mono(2-benzyl oxazoline) ligands. Our study focuses on exploring the impact of electrostatic interactions of aromatic π-electrons of the benzyl group, aimed at enhancing the structural rigidity of cationic Pd complexes. Introduction of an aromatic moiety, which weakly coordinates with the Pd cation, led to a two-fold increase in the stability of the Pd cationic complex compared to complexes lacking any coordinating substituents. This research represents the initial instance of a cationic Pd complex with 2-benzyl oxazolines, highlighting the importance of weak electrostatic interactions in elucidating the three-dimensional structure of a metal complex.

Interactions of sphingomyelin with biologically crucial side chain-hydroxylated cholesterol derivatives.

Oxysterols are interesting molecules due to their dual nature, reflecting beneficial and harmful effects on the body. An issue that still needs to be solved is how slight modification of their structure owing to the location of the additional polar group in the molecules affects their biological activity. With this in mind, we selected three side chain-hydroxylated oxysterols namely: 20(S)-hydroxycholesterol (20(S)-OH), 24(S)-hydroxycholesterol (24(S)-OH), and 27-hydroxycholesterol (27-OH), and examined their behavior in mixtures with the bioactive sphingolipid - sphingomyelin (SM). Our research was based on the Langmuir monolayer technique supplemented with molecular dynamics (MD) and microscopic observation of the films texture (Brewster angle microscopy, BAM, and atomic force microscopy, AFM). Additionally, since 20(S)-hydroxycholesterol has not been studied so far, we thoroughly characterized this oxysterol in one-component monolayers. Our studies showed differences in the interactions of the studied oxysterols and sphingomyelin. Namely, it was found that 20(S)-OH binds to SM, unlike 24(S)-OH and 27-OH, which both weakly interact with SM. This distinct behavior was interpreted within the molecular dynamics as being due to weak intermolecular interactions between 20(S)-OH molecules, which allowed easy incorporation of SM into the 20(S)-OH monolayer. In contrast, the strong oxysterol-oxysterol interactions occurring in monolayers with 24(S)-OH or 27-OH make this process more difficult. This may be important in the process of bone formation/resorption. Other aspects derived from our study are: (i) the tendency of oxysterols to incorporate into lipid rafts (leading to their modification in structure and function), as well as (ii) the formation of multilayer structures, in which oxysterols are arranged in the characteristic forms of "strings of beads", which may facilitate their transport across the membrane.