Acidified Nitrogen Self-Doped Porous Carbon with Superprotonic Conduction for Applications in Solid-State Proton Battery.

Solid proton electrolytes play a crucial role in various electrochemical energy storage and conversion devices. However, the development of fast proton conducting solid proton electrolytes at ambient conditions remains a significant challenge. In this study, a novel acidified nitrogen self-doped porous carbon material is presented that demonstrates exceptional superprotonic conduction for applications in solid-state proton battery. The material, designated as MSA@ZIF-8-C, is synthesized through the acidification of nitrogen-doped porous carbon, specifically by integrating methanesulfonic acid (MSA) into zeolitic imidazolate framework-derived nitrogen self-doped porous carbons (ZIF-8-C). This study reveals that MSA@ZIF-8-C achieves a record-high proton conductivity beyond 10-2  S cm-1 at ambient condition, along with good long-term stability, positioning it as a cutting-edge alternative solid proton electrolyte to the default aqueous H2 SO4 electrolyte in proton batteries.

Confined-Coordination Induced Intergrowth of Metal-Organic Frameworks into Precise Molecular Sieving Membranes.

Metal-organic framework (MOF) membranes with rich functionality and tunable pore system are promising for precise molecular separation; however, it remains a challenge to develop defect-free high-connectivity MOF membrane with high water stability owing to uncontrollable nucleation and growth rate during fabrication process. Herein, we report on a confined-coordination induced intergrowth strategy to fabricate lattice-defect-free Zr-MOF membrane towards precise molecular separation. The confined-coordination space properties (size and shape) and environment (water or DMF) were regulated to slow down the coordination reaction rate via controlling the counter-diffusion of MOF precursors (metal cluster and ligand), thereby inter-growing MOF crystals into integrated membrane. The resulting Zr-MOF membrane with angstrom-sized lattice apertures exhibits excellent separation performance both for gas separation and water desalination process. It was achieved H2 permeance of ~1200 GPU and H2/CO2 selectivity of ~67; water permeance of ~8 L ⋅ m-2 ⋅ h-1 ⋅ bar-1 and MgCl2 rejection of ~95 %, which are one to two orders of magnitude higher than those of state-of-the-art membranes. The molecular transport mechanism related to size-sieving effect and transition energy barrier differential of molecules and ions was revealed by density functional theory calculations. Our work provides a facile approach and fundamental insights towards developing precise molecular sieving membranes.

Two Organic-Inorganic Manganese(II) Halide Hybrids Showing Compelling Photo- and Mechanoluminescence as well as Rewritable Anticounterfeiting Printing.

Two organic-inorganic manganese(II) halide hybrids (OIMHs) with formulas of [(TEA)(TMA)]MnCl4 (1) and [(TPA)(TMA)3](MnCl4)2 (2) (TEA = tetraethylammonium, TMA = tetramethylammonium, and TPA = tetrapropylammonium) were synthesized by a mixed-ligand strategy. Both compounds crystallize in the acentric space group and are composed of isolated [MnCl4]2- tetrahedral units separated by two types of organic cations. They show high thermal stability and emit strong green light with different emission bandwidths, quantum yields, and high-temperature photostability. Remarkably, the quantum yield of 1 can reach up to 99%. Due to the high thermal stability and quantum yield of 1 and 2, green light-emitting diodes (LEDs) were fabricated. Furthermore, mechanoluminescence (ML) was observed in 1 and 2 when stress was applied. The ML spectrum of 1 is similar to the photoluminescence (PL) spectrum, suggesting ML and PL emissions come from the same transition of Mn(II) ions. Finally, rewritable anticounterfeiting printing and information storage were achieved by utilizing the outstanding photophysical properties and ionic features of the products. The printed images still remain clear after several cycles, and the information stored on the paper can be read out by a UV lamp and commercial mobile phones.

Relationship between the Co-Continuous Morphology of Immiscible Polymer Blends and the Structure of an In Situ Formed Graft Copolymer.

In order to get stable co-continuous morphology in immiscible polymer blends, besides reducing the interfacial tension, the compatibilizer should not only promote the formation of flat interface between different phases, but also not hinder the coalescence of the dispersed phase. Herein, the relationship between the morphology of the compatibilized polystyrene/nylon 6/styrene-maleic anhydride (PS/PA6/SMA) immiscible polymer blends and the structures of the in-situ formed SMA-g-PA6 graft copolymers as well as the processing conditions are studied. Two kinds of SMA are used: SMA28 (28 wt.% MAH) and SMA11 (11 wt.% MAH). After melt blending with PA6, the in-situ formed copolymer SMA28-g-PA6 has on average of four PA6 side chains, while that of SMA11-g-PA6 has only one. Dissipative particle dynamics simulation results indicate that both SMA28-g-PA6 copolymer and PS/PA6/SMA28 blends tend to form co-continuous structure, while those related to SMA11 intend to form sea-island morphologies. These results are correct only at relatively low rotor speed (60 rpm). When the rotor speed is higher (105 rpm), sea-island morphologies are obtained in SMA28 systems, while that for SMA11 ones are co-continuous. This indicates that higher shear stress can elongate the minor phase domains to form flat interfaces, while the SMA28-g-PA6 copolymers can be pulled out from the interface.

Tuning the hardness and crack resistance through liquid-liquid phase separation in an aluminosilicate glass.

Here, spinodal decomposition is used as a strategy to enhance the mechanical properties of the 30Al2O3·70SiO2 glass. The melt-quenched 30Al2O3·70SiO2 glass exhibited a liquid-liquid phase separation with an interconnected snake-like nano-structure. Through further heat treatment at 850 °C for different durations of up to 40 hours, we observed a continuous increase of up to about 0.90 GPa in hardness (Hv) together with a drop in the slope for Hv rise at 4 hours. However, the crack resistance (CR) achieved a maximum value of 13.6 N when the heat treatment time was 2 hours. Detailed calorimetric, morphological and compositional analyses were conducted to elucidate the effect of tuning the thermal treatment time on hardness and crack resistance. These findings pave the way to utilize the spinodal phase-separated phenomena to enhance the mechanical properties of glasses.

Metal-Organic Framework-Derived N-Doped Porous Carbon for a Superprotonic Conductor at above 100 °C.

The development of proton conductors capable of working at above 100 °C is of great significance for proton exchange membrane electrolysis cells (PEMECs) and proton exchange membrane fuel cells (PEMFCs) but remains to be an enormous challenge to date. In this work, we demonstrate for the first time that the N-doped porous carbon derived from metal-organic frameworks (MOFs) with great superiority can be exploited for high-performing proton conductors at above 100 °C. Through the pyrolysis of ZIF-8, the N-doped porous carbon (ZIF-8-C) featuring high chemical resistance to Fenton's reagent was readily prepared and then served as a robust host to accommodate H3PO4 molecules for proton transport. Upon impregnation with H3PO4, the resulting PA@ZIF-8-C exhibits low water swelling and high proton conduction of over 10-2 S cm-1 at a temperature above 100 °C, which is superior to many reported proton conductors. This work provides a new approach for the design of high-performing proton conductors at above 100 °C.

Characterization and Risk Assessment of Heavy Metals in River Sediments on the Western Bank of Taihu Lake, China.

In this study, nine heavy metals (Cd, Cr, As, Hg, Pb, Cu, Ni, Be, and Sb) in the sediments of 17 typical rivers on the western bank of Taihu Lake were determined. Several statistical methods were applied to analyze the distribution, sources, pollution status, and potential ecological risk of these metals. The mean concentrations of heavy metals in sediments other than Be exceeded their local background values. Geoaccumulation index and potential ecological risk index analyses demonstrated that most sediment samples were contaminated and may pose ecological risks, especially those from the Taihu Lake estuary. In particular, Cd concentrations indicated moderate contamination and potentially serious to severe ecological risk. Principal component, cluster, and correlation analyses demonstrated that Ni, Sb, Cr, and Cu were derived from industrial sources, whereas the other metals had complex origins.

A Semiconductive Nature of Bis(dithiolato)nickelate Radical Salt Exhibiting Broadband Photoconduction.

The fractional oxidation state [M(dmit)2] (dmit2- = 2-thioxo-1, 3-dithiole-4, 5-dithiolate) salts have long attracted attention in the molecular metal area owing to high conductivity and even superconductivity. In this study, we achieved a mixed-valence salt (1) of [Ni(dmit)2]0.5- with monovalent 1,3-N,N-dimethyl-imidazolium (DiMIm+) by a solvent evaporation approach under ambient conditions. The mixed valence of [Ni(dmit)2]0.5- has been characterized by an analysis of the IR spectrum and crystal structure. In the crystal structure of 1, two [Ni(dmit)2]0.5- anions overlap in an eclipsed mode to form a [Ni(dmit)2]21- dimer, featuring a radical bearing an S = 1/2 spin; the dimeric radicals stack into a column along the b axis, and the adjacent columns connect together via the lateral-to-lateral S···S contacts along the a axis, and through the head-to-head S···S contacts along the [101] direction. Salt 1 shows the magnetic behavior of an S = 1/2 Heisenberg antiferromagnetic uniform linear chain with J/kB = -47.5(4) K and a semiconducting feature with σ = 2.52 × 10-3 S cm-1 at 293 K, 2.32 × 10-2 S cm-1 at 373 K, and Ea = 0.22 eV, as well as broadband photoconductivity under irradiation of green and white lights. This study suggests the possibility of designing new photoconductors based on the mixed-valence [Ni(dmit)2]0.5- salt.

Proton Conduction of an Acid-Resistant Open-Framework Chalcogenidometalate Hybrid in Anhydrous versus Humid Environments.

Solid proton conductors are broadly applicable to various electrochemical devices; therefore, it is highly desirable to develop robust materials with high proton conductivity under both anhydrous and humid environments within a wide temperature range. In this work, we investigated the proton conducting properties of a 3D open-framework chalcogenidometalate hybrid, [CH3NH3]2[H3O]Ag5Sn4Se12·C2H5OH (1), which exhibited both anhydrous and water-assisted proton conduction. Importantly, the excellent thermal and chemical stabilities of hybrid 1 are superior to many MOF-based proton conducting materials. This present study proved to be a considerable advance based on open-framework chalcogenidometalates in the design of robust solid proton conducting materials that are capable of operating under humid and anhydrous environments in a wide temperature range.

A Rotorlike Supramolecular Assembly, {[K(18-crown-6)]PbI3}∞, with a Reversible Breaking-Symmetry Phase Transition near Room Temperature.

A rotorlike supramolecular crystal, {[K(18-crown-6)]PbI3}∞, is composed of a linear [PbI3]∞ chain acting as a stator and [K(18-crown-6)]+ cations fastened to the [PbI3]∞ chain and K-I bond like rotators and axes, respectively. A reversible breaking-symmetry phase transition occurs at ∼305 K. Variable-temperature 1H NMR spectra and dielectrics were used for the dynamic analysis of [K(18-crown-6)]+ cations in the crystal.

NS3 from Hepatitis C Virus Strain JFH-1 Is an Unusually Robust Helicase That Is Primed To Bind and Unwind Viral RNA.

Hepatitis C viruses (HCV) encode a helicase enzyme that is essential for viral replication and assembly (nonstructural protein 3 [NS3]). This helicase has become the focus of extensive basic research on the general helicase mechanism, and it is also of interest as a novel drug target. Despite the importance of this protein, mechanistic work on NS3 has been conducted almost exclusively on variants from HCV genotype 1. Our understanding of NS3 from the highly active HCV strains that are used to study HCV genetics and mechanism in cell culture (such as JFH-1) is lacking. We therefore set out to determine whether NS3 from the replicatively efficient genotype 2a strain JFH-1 displays novel functional or structural properties. Using biochemical assays for RNA binding and duplex unwinding, we show that JFH-1 NS3 binds RNA much more rapidly than the previously studied NS3 variants from genotype 1b. Unlike NS3 variants from other genotypes, JFH-1 NS3 binds RNA with high affinity in a functionally active form that is capable of immediately unwinding RNA duplexes without undergoing rate-limiting conformational changes that precede activation. Unlike other superfamily 2 (SF2) helicases, JFH-1 NS3 does not require long 3' overhangs, and it unwinds duplexes that are flanked by only a few nucleotides, as in the folded HCV genome. To understand the physical basis for this, we solved the crystal structure of JFH-1 NS3, revealing a novel conformation that contains an open, positively charged RNA binding cleft that is primed for productive interaction with RNA targets, potentially explaining robust replication by HCV JFH-1.IMPORTANCE Genotypes of HCV are as divergent as different types of flavivirus, and yet mechanistic features of HCV variants are presumed to be held in common. One of the most well-studied components of the HCV replication complex is a helicase known as nonstructural protein 3 (NS3). We set out to determine whether this important mechanical component possesses biochemical and structural properties that differ between common strains such as those of genotype 1b and a strain of HCV that replicates with exceptional efficiency (JFH-1, classified as genotype 2a). Indeed, unlike the inefficient genotype 1b NS3, which has been well studied, JFH-1 NS3 is a superhelicase with strong RNA affinity and high unwinding efficiency on a broad range of targets. Crystallographic analysis reveals architectural features that promote enhanced biochemical activity of JFH-1 NS3. These findings show that even within a single family of viruses, drift in sequence can result in the acquisition of radically new functional properties that enhance viral fitness.

Double optical gating for generating high flux isolated attosecond pulses in the soft X-ray regime.

Double optical gating (DOG) technique was implemented with a two-cycle, 1.7 µm driving field to generate isolated attosecond pulses in the 100-250 eV spectrum range. The strong ellipticity dependency of the high harmonics from the 1.7 µm driving field makes polarization based gating method very efficient. When a second harmonic (SH) field is introduced, complete gating can be achieved with less ionization from the leading edge of the driving field, which yields supercontinua with a pulse energy of 0.3 nJ. We perform an attosecond streaking measurement to confirm the generation of isolated attosecond pulses.

In-line Spectral Interferometry in Shortwave-Infrared Laser Filaments in Air.

We investigate the nonlinear propagation of intense, two-cycle, carrier-envelope phase (CEP) stable laser pulses at 1.7 µm center wavelength in air. We observe CEP-dependent spectral interference in the visible part of the forward-propagating white light generated on propagation. The effect is robust against large fluctuations of the input pulse energy. This robustness is enabled by rigid clamping of both the peak optical field and the phase of the propagating waveform, which has been revealed by numerical simulations. The CEP locking can enhance the yield of the CEP-dependent strong-field processes in gaseous media with long-wavelength drivers, while the observed spectral interference enables single-shot, stand-off CEP metrology in the atmosphere.

Two-Step Structure Phase Transition, Dielectric Anomalies, and Thermochromic Luminescence Behavior in a Direct Band Gap 2D Corrugated Layer Lead Chloride Hybrid of [(CH3 )4 N]4 Pb3 Cl10.

A direct band gap 2D corrugated layer lead chloride hybrid, [(CH3 )4 N]4 Pb3 Cl10 (1), shows analogous topology to the {Mg3 F10 4- }∞ layer in Cs4 Mg3 F10 , and with the (CH3 )4 N+ cations locating in the inorganic layer voids and between the interlayers. Two reversible structural phase transitions occur in 1 at 225/210 K and 328/325 K upon heating/cooling, respectively. On going from the low- to intermediate-temperature phase, the space group changes from P21 /c to Cmca, and the crystallographic axis perpendicular to the layers is doubled with the order-disorder transformation of (CH3 )4 N+ cations between the interlayers. The intermediate- and high-temperature phases are isomorphic with similar cell parameters and packing structure; their main difference concerns the disorder degree of the (CH3 )4 N+ cations between the interlayers. The two-step structural phase transitions lead to dielectric anomalies around the corresponding Tc . Interestingly, 1 shows multiband emission, originating from the recombination of exciton and emission of defects. Moreover, 1 exhibits divergent thermochromic luminescent features around the Tc on the intermediate to low temperature transition.

Design and Preparation of a Superior Proton Conductor by Confining Tetraethylenepentamine in the Pores of ZIF-8 To Induce Further Adsorption of Water and Carbon Dioxide.

In this work, we present a new strategy toward the design and preparation of a metal-organic framework- or porous coordination polymer-based superior proton conductor. We chose a robust metal-organic framework, ZIF-8, as the host and a flexible aliphatic alkylpolyamine, tetraethylenepentamine (TEPA), as the guest, and we successfully prepared an encapsulation compound TEPA@ZIF-8 via the facile insertion of TEPA into the pores of ZIF-8, which was characterized by microanalysis, thermogravimetric analysis, IR spectroscopy, N2, water vapor adsorption-desorption, and other methods. Each cage in ZIF-8 is occupied by ∼1.44 TEPA molecules, and the introduced TEPA further adsorbs H2O and CO2 from air to offer a superior proton conductor, TEPA@ZIF-8-H2CO3, with σ = 2.08 × 10-3 S cm-1 at 293 K and 99% relative humidity, and excellent proton conduction durability. Regarding ZIF-8, the proton conductivity of TEPA@ZIF-8-H2CO3 increases by 3 orders of magnitude at the same condition, and the activation energy decreases by 0.91 eV. Remarkably, TEPA@ZIF-8-H2CO3 also shows promising features for the detection of aqueous ammonia. This work provides more opportunities to achieve superior protonic conducting materials and suggests that MOF-based proton conductors possess great potential for applications in ammonia sensing.

Stereochemically Active and Inactive Lone Pairs in Two Room-Temperature Phosphorescence Coordination Polymers of Pb2+ with Different Tricarboxylic Acids.

Two new Pb2+-based coordination polymers (CPs), [Pb2(HBTC)2(DMF)] (1) and [Pb(HPTC)] (2), have been synthesized under solvothermal condition; herein, H3BTC and H3PTC represent 1,3,5-benzenetricarboxylic acid and 2,4,6-pyridine tricarboxylic acid, respectively. Both 1 and 2 were characterized by microanalysis, infrared spectra (IR), thermal gravimetric analyses (TGA), and powder X-ray diffraction (PXRD) techniques. Single-crystal structural analysis indicates that 1 and 2 show different coordination sphere around Pb2+ ions and distinct coordination frameworks. The I1O2 type three-dimensional (3D) nonporous metal-organic framework forms in 1, where the Pb2+ ion shows holo-directed coordination geometry, while the I0O2 type two-dimensional (2D) coordination polymeric layered structure forms in 2, where Pb2+ ion shows a hemidirected coordination sphere and the 6s2 lone electron pair in Pb2+ ion is stereochemically active. The two CPs emit intense and long-lasting greenish phosphorescence in air at room temperature, with absolute quantum yields of 1.2% for 1 and 4.7% for 2 and decay lifetimes of 0.73 ms for 1 and 1.52 ms for 2.

Selective RNA targeting and regulated signaling by RIG-I is controlled by coordination of RNA and ATP binding.

RIG-I is an innate immune receptor that detects and responds to infection by deadly RNA viruses such as influenza, and Hepatitis C. In the cytoplasm, RIG-I is faced with a difficult challenge: it must sensitively detect viral RNA while ignoring the abundance of host RNA. It has been suggested that RIG-I has a 'proof-reading' mechanism for rejecting host RNA targets, and that disruptions of this selectivity filter give rise to autoimmune diseases. Here, we directly monitor RNA proof-reading by RIG-I and we show that it is controlled by a set of conserved amino acids that couple RNA and ATP binding to the protein (Motif III). Mutations of this motif directly modulate proof-reading by eliminating or enhancing selectivity for viral RNA, with major implications for autoimmune disease and cancer. More broadly, the results provide a physical explanation for the ATP-gated behavior of SF2 RNA helicases and receptor proteins.

Modeling Insight into Battery Electrolyte Electrochemical Stability and Interfacial Structure.

Electroactive interfaces distinguish electrochemistry from chemistry and enable electrochemical energy devices like batteries, fuel cells, and electric double layer capacitors. In batteries, electrolytes should be either thermodynamically stable at the electrode interfaces or kinetically stable by forming an electronically insulating but ionically conducting interphase. In addition to a traditional optimization of electrolytes by adding cosolvents and sacrificial additives to preferentially reduce or oxidize at the electrode surfaces, knowledge of the local electrolyte composition and structure within the double layer as a function of voltage constitutes the basis of manipulating an interphase and expanding the operating windows of electrochemical devices. In this work, we focus on how the molecular-scale insight into the solvent and ion partitioning in the electrolyte double layer as a function of applied potential could predict changes in electrolyte stability and its initial oxidation and reduction reactions. In molecular dynamics (MD) simulations, highly concentrated lithium aqueous and nonaqueous electrolytes were found to exclude the solvent molecules from directly interacting with the positive electrode surface, which provides an additional mechanism for extending the electrolyte oxidation stability in addition to the well-established simple elimination of "free" solvent at high salt concentrations. We demonstrate that depending on their chemical structures, the anions could be designed to preferentially adsorb or desorb from the positive electrode with increasing electrode potential. This provides additional leverage to dictate the order of anion oxidation and to effectively select a sacrificial anion for decomposition. The opposite electrosorption behaviors of bis(trifluoromethane)sulfonimide (TFSI) and trifluoromethanesulfonate (OTF) as predicted by MD simulation in highly concentrated aqueous electrolytes were confirmed by surface enhanced infrared spectroscopy. The proton transfer (H-transfer) reactions between solvent molecules on the cathode surface coupled with solvent oxidation were found to be ubiquitous for common Li-ion electrolyte components and dependent on the local molecular environment. Quantum chemistry (QC) calculations on the representative clusters showed that the majority of solvents such as carbonates, phosphates, sulfones, and ethers have significantly lower oxidation potential when oxidation is coupled with H-transfer, while without H-transfer their oxidation potentials reside well beyond battery operating potentials. Thus, screening of the solvent oxidation limits without considering H-transfer reactions is unlikely to be relevant, except for solvents containing unsaturated functionalities (such as C═C) that oxidize without H-transfer. On the anode, the F-transfer reaction and LiF formation during anion and fluorinated solvent reduction could be enhanced or diminished depending on salt and solvent partitioning in the double layer, again giving an additional tool to manipulate the order of reductive decompositions and interphase chemistry. Combined with experimental efforts, modeling results highlight the promise of interphasial compositional control by either bringing the desired components closer to the electrode surface to facilitate redox reaction or expelling them so that they are kinetically shielded from the potential of the electrode.

Generation of 1 kHz, 2.3 mJ, 88 fs, 2.5 µm pulses from a Cr2+:ZnSe chirped pulse amplifier.

We demonstrate the generation of 2.3 mJ, 88 fs, 2.5 µm laser pulses at 1 kHz repetition rate from a three-stage chirped pulse amplifier employing Cr2+:ZnSe crystals as the active gain media. 5 µJ seed of the amplifier is obtained via intrapulse difference frequency generation in a bismuth triborate (BIBO) crystal from spectrally broadened Ti:Sapphire amplifier output. A multi-pass amplifier followed by two single-pass amplifiers pumped by Q-switched Ho:YAG lasers boost the pulse energy to 6.5 mJ, yielding 2.3 mJ, 88 fs pulses upon pulse compression. Our results show the highest peak power at 2.5 µm with 1 kHz repetition rate. Such a laser will be a powerful source for studying strong-field physics and extending high-harmonic generation towards the keV region.

Comprehensively Understanding Isomorphism and Photoluminescent Nature of Two-Dimensional Coordination Polymers of Cd(II) and Mn(II) with 1,1'-Ethynebenzene-3,3',5,5'-tetracarboxylic Ligand.

Four isomorphic two-dimensional (2D) homo- and heterometallic coordination polymers (CPs), [(Cd xMn1- x)3(HEBTC)2(DMSO)6] with x = 1 (1), 1/3 (2), 0.5 (3), and 2/3 (4) were prepared by conventional one-pot self-assembly approach, using Cd2+ or mixtures of Cd2+ and Mn2+ with 1,1'-ethynebenzene-3,3',5,5'-tetracarboxylic (H4EBTC) under solvothermal conditions. The crystal structures of four isomorphic CPs are composed of center-symmetric trinuclear metal clusters building units linked by HEBTC3- ligands, extending into (3, 6)-connected topological 2D nets. Four CPs are isomorphic to the Mn-CP, [Mn3(HEBTC)2(DMSO)6], we recently reported. The solid-state photoluminescence of 1-4 shows dual emissions at ambient condition, where the emission bands centered at ca. 390 and 562 nm in 1 are assigned to the fluorescence and phosphorescence within HEBTC3- ligand, respectively; however, the emission bands centered at around 397 and 470 nm in 2-4 are attributed to fluorescence, corresponding to electron transition within HEBTC3- ligand and MLCT transition between HEBTC3- ligand and Mn2+ ion. In addition, the origin of isomorphism between 1 and Mn-CP is also discussed.