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We report the synthesis and characterization of a new water-soluble cavitand 1. The container features 2-aminobenzimidazole panels at the "rim" and pyridiniums at the "feet". In the solid state, a single-crystal X-ray structure of the organic-soluble precursor 2 showed a stable vase form. The structure is stabilized by hydrogen-bonded bridges between adjacent panels through solvents and ions. In aqueous solution, binding of hydrophobic and amphiphilic guest molecules to 1 was investigated using 1H NMR. Alkanes, alcohols, acids, diols, and diacids formed 1:1 host-guest complexes, and the guest conformations were deduced from characteristic chemical shift changes. In the presence of [Pd(ethylenediamine)(H2O)2·2NO3], cavitand 1 formed a complex incorporating two metals. The metal-coordinated cavitand also bound hydrophobic linear alkanes and difluorobenzene isomers in aqueous medium. The metallo-cavitand showed shape and size selectivity and was used to separate o-difluorobenzene from its isomers as observed by 19F NMR spectroscopy. The primary amino function of the cavitands offers possibilities for further elaboration to covalent clusters of these container compounds.

Bone mineral consists of calcium hydroxy-carbonate apatite (HCA) that incorporates other minor cation substituents, primarily Na+ (0.5–0.8 wt %). We examine the carbonate species in various HCA spe...

P2-type Na0.67Mn0.75Fe0.25O2 cathode materials with low cost and high specific capacity have aroused much interest for sodium-ion batteries. Nevertheless, the cyclic and structural stabilities need...

Lithium-metal batteries (LMBs) are promising electrochemical energy storage devices with high energy densities. However, the extreme reactivity of metallic lithium, the large volumetric change of the electrode during cycling, and the notorious dendrite formation issues lead to low cyclic stability and safety concerns, hindering the practical application of LMBs. In particular, the intrinsic tendency of uneven lithium deposition and the large internal electrode stress lead to the piecing of solid electrolyte interphases (SEIs), thereby resulting in fast decay of the anode. We develop a facile laser processing technique to fabricate laser-structured copper foils (LSCFs) that are able to regulate the lithium deposition kinetics and increase the cycle life of LMBs. By simply scribing commercial foils using a 355 nm laser, microstructural features with fish-scale patterns are obtained. The lithium deposition follows a drastically different mode on the LSCF compared with commercial planar copper foils which relieves the internal stress of lithium and prohibits the piecing of SEI. A high Coulombic efficiency of >96% of the lithium metal anode is maintained for over 100 cycles on the LSCF at a current density of 1 mA cm-2 and an areal capacity of 1 mAh cm-2 while the benchmark decayed to below 80% after 50 cycles. Full cells based on LiFePO4 cathodes display a reasonable specific capacity of 125 mAh g-1 over 300 cycles at a rate of 1 C. This work provides a fast yet effective laser-based approach to construct highly stable lithium metal anodes.

Magnetic liquid metal is regarded as a promising material due to its integration of fluidic, metallic, and magnetic properties simultaneously. Previously, few methods of fabricating magnetic liquid metal have been proposed. However, either the alloying reaction inside the matrix or the poor performance in electrical and thermal conduction is troublesome in practical applications. Here, inspired by the mussel in nature, polydopamine is introduced to in situ reduce and immobilize silver shells on the surface of iron particles, and then the modified particles mix with liquid metal to prepare liquid metal-based magnetic suspensions (LMMSs). The silver shells can prevent iron particles from alloying with liquid metal and enhance the electrical and thermal conductivities of the LMMS concurrently. Besides, the LMMS thus obtained can keep its magnetism intact for a long period, at least during the 60 days of the test. Compared to directly mixing bare iron particles with liquid metal, the maximum electrical conductivities increase by at least 13.69% and the thermal conductivities increase by almost 4 times in the LMMS. The LMMS also exhibits potential applications in patterning and magnetic manipulation. This work puts forward a new strategy for preparing a LMMS with appealing properties and its broad applications are expected in the future.

Red pericarp associates with seed dormancy or preharvest sprouting (PHS) tolerance in crops. To identify this association's molecular mechanism, a PHS mutant Osviviparous1 (Osvp1) was characterized in rice and crossed with Kasalath, a red pericarp cultivar with Rc (red coleoptiles) genotype. Among the dehulled seeds of F2 progenies, RcRcvp1vp1 seeds performed a lower PHS rate than rcrcvp1vp1 seeds and showed shallower pigmentation than RcRcVP1VP1 seeds. Kasalath and SL9 (an RcRcVP1VP1 substitution line with Nipponbare background) showed more ABA sensitivity than the Nipponbare (rcrcVP1VP1) by the germination assay, and the transcriptional abundance of ABA signal genes OsABI2, OsSnRK2, OsVP1, ABI5, and especially OsVP1 increased in the red pericarp line SL9. Moreover, OsVP1 can directly bind Rc (bHLH) promoter by yeast one-hybrid, which activates Rc and OsLAR expression in red pericarp rice. Furthermore, a luciferase complementation imaging assay showed that OsVP1 interacts with transcriptions factors Rc and OsC1. These results indicate that OsVP1 promotes proanthocyanidin accumulation through the interaction among OsVP1, Rc, and OsC1 and then increases the plant's ABA sensitivity and PHS resistance.

Klebsiella pneumoniae causes pneumonia and liver abscesses in humans worldwide and contains virulence factor capsular polysaccharides and lipopolysaccharides linked to the cell wall. Although capsular polysaccharides are good antigens for vaccine production and capsular oligosaccharides conjugate vaccines are proven effective against infections caused by encapsulated pathogens, there is still no Klebsiella pneumoniae vaccine available. One obstacle is that the capsular polysaccharide of a dominated Klebsiella pneumoniae serotype K2 is difficult to synthesize chemically due to the three 1,2-cis linkages in its structure. In this study, we successfully synthesized K2 capsular polysaccharides from tetra- to octasaccharides in highly a stereoselective manner. Subsequently, three synthesized glycans were conjugated to DT protein to provide glycoconjugate vaccine candidates (DT-Hexa, DT-Hepta, and DT-Octa) that were used in in vivo immunization experiments in mice. The results of immunized studies showed all three glycoconjugates elicited antibodies that recognized all of the synthetic glycans at 1:200-fold dilution. Particularly, the DT-Hepta conjugate elicited a higher level of antibodies that can recognize longer glycan (octasaccharide) even at 1:12800-fold dilution and exhibited good bactericidal activity. Our results concluded that heptasaccharide is the minimal epitope and a potential candidate for the vaccine against the K2 sero group of Klebsiella pneumoniae.

Here, we report a β-galactosidase (β-Gal)-responsive photochromic fluorescent probe, NpG, that was designed to prebind to human serum albumin (HSA) to form the probe/protein hybrid, NpG@HSA. The formation of NpG@HSA led to an increase in fluorescence emission (520 nm) corresponding to the binding of the fluorescent naphthalimide unit with HSA. In addition, this enabled visualization of the spiropyran fluorescence emission in aqueous media. Our probe/protein hybrid approach afforded a unique imaging platform with enhanced cell permeability and solubility that was capable of visualizing the cellular uptake of NpG@HSA before its activation by β-Gal. The β-Gal-mediated cleavage of the galactose unit within the NpG@HSA hybrid resulted in the formation of NpM@HSA and an increase in red fluorescence emission (620 nm). The resultant merocyanine unit was then able to undergo photoisomerization (merocyanine ↔ spiropyran) to facilitate STORM (i.e., stochastic optical reconstruction microscopy) imaging with minimal phototoxicity and excellent photostability/reversibility. Using STORM, NpG@HSA was able to determine the subcellular distribution of β-Gal activity between cell lines with nanoscale precision. We believe that this system represents a versatile imaging platform for the design of photochromic fluorescent probes suitable for illuminating the precise location of disease-specific biomarkers in various cellular processes.

From a multitude of homonuclear and heteronuclear correlation magic-angle-spinning (MAS) NMR experiments, we present thorough structural and phase-quantification analyses of calcium phosphate cemen...

N-glycans on the cell surface provide distinct signatures that are recognized by different glycan-binding proteins (GBPs) and pathogens. Most glycans in humans are asymmetric and isomeric, yet their biological functions are not well understood due to their lack of availability for studies. In this work, we have developed an improved strategy for asymmetric N-glycan assembly and diversification using designed common core substrates prepared chemically for selective enzymatic fucosylation and sialylation. The resulting 26 well-defined glycans that carry the sialic acid residue on different antennae were used in a microarray as a representative application to profile the binding specificity of hemagglutinin (HA) from the avian influenza virus (H5N2). We found distinct binding affinity for the Neu5Ac-Gal epitope linked to the N-acetylglucosamine (GlcNAc) of different branches and only a minor effect in binding for the terminal galactose on different branches. Overall, the microarray analysis showed branch-biased and context-based recognition patterns.

Here, we demonstrate a novel donor-intermediate-receptor energy transfer model through a Ce3+ → Tb3+ → Eu3+ scheme in a CaTbAl3O7:Ce3+,Eu3+ nanocrystalline phosphor. A new type of CaTbAl3O7 and CaT...

Discovery of novel liver injury indicators and development of practical assays to detect target indicator(s) would strongly facilitate the diagnosis of liver disorders. Herein, an alternative biomarker discovery strategy was applied to find suitable endoplasmic reticulum-resident protein(s) as serologic indicator(s) for hepatocyte injury via analysis of the human proteome database among plasma and various organs. Both database searching and preliminary experiments suggested that human carboxylesterase 1A (CES1A), one of the most abundant and hepatic-restricted proteins, could serve as a good serologic indicator for hepatocyte injury. Then, a highly selective and practical bioluminescent sensor was developed for real-time sensing of CES1A in various biological systems including plasma. With the help of this bioluminescent sensor, the release of hepatic CES1A into the extracellular medium or the circulation system could be directly monitored. Further investigations demonstrated that serum activity levels of CES1A were elevated dramatically in mice with liver injury or patients with liver diseases. Collectively, this study provided solid evidence to support that CES1A was a novel serological indicator for hepatocyte injury. Furthermore, the strategy used in this study paved a new way for the rational discovery of practical indicators to monitor the dynamic progression of injury in a given tissue or organ.

Supramolecular capsules are desirable containers for the study of molecular behavior in small spaces and offer applications in transport, catalysis, and material science. We report here the use of chalcogen bonding to form container assemblies that are stable in water. Cavitands

The oxygen reduction reaction (ORR) plays an irreplaceable role in many energy-conversion processes. Low-cost catalysts with high activity and stability are eagerly needed to improve the sluggish O...

For the development of advanced flexible and wearable electronic devices, functional electrolytes with excellent conductivity, temperature tolerance, and desirable mechanical properties need to be engineered. Herein, an alkaline double-network hydrogel with high conductivity and superior mechanical and antifreezing properties is designed and promisingly utilized as the flexible electrolyte in all-solid-state zinc-air batteries. The conductive hydrogel is comprised of covalently cross-linked polyelectrolyte poly(2-acrylamido-2-methylpropanesulfonic acid potassium salt) (PAMPS-K) and interpenetrating methyl cellulose (MC) in the presence of concentrated alkaline solutions. The covalently cross-linked PAMPS-K skeleton and interpenetrating MC chains endow the hydrogel with good mechanical strength, toughness, an extremely rapid self-recovery capability, and an outstanding antifatigue property. Gratifyingly, the entrapment of a concentrated alkaline solution in the hydrogel matrix yields an extremely high ionic conductivity (105 mS cm-1 at 25 °C) and an excellent antifreezing capacity. The hydrogel retains comparable conductivity and eligible strength to withstand various mechanical deformations at -20 °C. The all-solid-state zinc-air batteries using PAMPS-K/MC hydrogels as flexible alkaline electrolytes exhibit comparable values of specific capacity (764.7 mAh g-1), energy capacity (850.2 mWh g-1), cycling stability, and mechanical flexibility. The batteries still possess competitive electrochemical performances even when the operating temperature drops to -20 °C.

This study represents a systematic chemical and biological study of the rufomycin (RUF) class of cyclic heptapeptides, which our anti-TB drug discovery efforts have identified as potentially promising anti-TB agents that newly target the caseinolytic protein C1, ClpC1. Eight new RUF analogues, rufomycins NBZ1-NBZ8 (1-8), as well as five known peptides (9-13) were isolated and characterized from the Streptomyces atratus strain MJM3502. Advanced Marfey's and X-ray crystallographic analysis led to the assignment of the absolute configuration of the RUFs. Several isolates exhibited potent activity against both pathogens M. tuberculosis H37Rv and M. abscessus, paired with favorable selectivity (selectivity index >60), which collectively underscores the promise of the rufomycins as potential anti-TB drug leads.

Understanding and controlling parasitic reactions at the electrode–electrolyte interface (EEI) in Li-ion batteries is essential to enhance and predict the battery cycle life. Recent work has shown ...

Oxidative cleavage reactions of arylalkenes by tert-butyl hydroperoxide that occur by free radical processes provide access to carboxylic acid or ketone products. However, the pathway to these cleavage products is complex, initiated by regioselective oxygen radical addition to the carbon-carbon double bond. Subsequent reactions of the initially formed benzyl radical lead eventually to carbon-carbon cleavage. Thorough investigations of these reactions have identified numerous reaction intermediates that are on the pathways to final product formation, and they have identified a new synthetic methodology for the synthesis of peroxy radical addition-induced hydroperoxide formation.

A strategy of aerobic oxidative C(sp3)–C(sp3) bond cleavage of N-ethylaniline derivatives bearing azaarenes for the synthesis of N-aryl formamides has been developed. This approach was carried out ...

A copper-catalyzed asymmetric hydrosilylation of β-nitroethyl aryl ketones has been disclosed, and the corresponding chiral alcohols could be obtained in high yields (up to 99% yield) and excellent enantioselectivities (up to 96% ee). Moreover, the reaction worked well on a gram scale with 0.3 mol % of ligand loading, indicating that our protocol has potential applications in the synthesis of important pharmaceuticals such as Tranylcypromine and Ticagrelor.

Since the positive influences of defects on the performance of electroceramics were discovered, investigations concerning on defects and aliovalent doping routes have grown rapidly in the fields of inorganic chemistry and condensed matter physics. In this article, we summarized the types of defects in electroceramics as well as characterization tools of defects and highlighted the effects of intrinsic and extrinsic defects on the material performances with the emphasis on dielectric, ferroelectric, and piezoelectric properties. We mainly introduced defect related theoretical simulation and experimental results in several typical incipient ferroelectrics, ferroelectrics, and antiferroelectrics. Hence, the influences of defects on the crystal lattice were summed up, and then the main physical mechanisms were highlighted. Particularly, the performance enhancements of aliovalently doped electroceramics were also evaluated and reviewed. Finally, the outlook and challenges were discussed on the basis of their current developments. This article covers not only an overview of the state-of-the-art advances of defects and aliovalent doping routes in electroceramics but also the future prospects that may open another window to tune the electrical performance of electroceramics via intentionally introducing certain defects.

A new mechanism of La-catalyzed amidation of N-methylbenzylamine with p-chlorobenzaldehyde has been computationally proposed, where L2La[NR1R2] (I) rather than previously proposed L2La[OCHRNR1R2] (II) is the catalytically active species. Interestingly, the side-product alcohol acting as a proton relay to reduce reaction energy barrier could participate in the regeneration of I. Besides, DFT calculations suggest that an addition of alcohol additive into the initial reaction system could accelerate the reaction, which has been further verified by experiments.

Silicon germanium (SiGe) alloys hold promise for thermoelectric power generation at high temperatures and have been applied in deep-space missions. However, enhancement of the dimensionless thermoelectric figure-of-merit (ZT) is still needed for practical civil applications of SiGe. In this work, we report high-performance oxide/SiGe bulk composites that were obtained via hot-press sintering of mixed powders composed of phosphorus (P)-doped SiGe prepared via mechanical alloying, using a ball-milling technique and La-Nb-doped SrTiO3 (La-Nb-STO). The La-Nb-STO powder was obtained from ball milling of a bulk La-Nb-STO sample that was sintered via hot pressing of hydrothermally synthesized La-Nb-STO powder. Controlling the amount of La-Nb-STO nanoparticles added to SiGe matrix increased the power factor by optimizing the electron concentration and mobility in the composite. In addition, compared with single-phase P-doped SiGe, the second phase decreased the thermal conductivity because of additional phonon scattering at the interface. As a result, a high ZT of 0.91 was realized in the n-type oxide/SiGe bulk composite at 1000 K, which was 18% larger than that for the typical materials used in space flight missions and 5% higher than the single-phase SiGe alloys obtained in the present study. The strategy used in this study could also be viable to further enhance the ZT of nanostructured n-type SiGe and SrTiO3-based oxide materials.

In a study of the potential anti-inflammatory constituents from Kalimeris shimadae, six new sesquiterpenes, kalshinoids A-F (1-6), together with 21 known compounds (7-27), were isolated. The structures and absolute configurations of the new compounds were discerned from extensive spectroscopic analysis, and the absolute configurations of kalshinoids A, B, E, and F were established by ECD calculations. Furthermore, the identified compounds were tested for anti-inflammatory activity as assessed by inhibition of tumor necrosis factor-alpha (TNF-α) in THP-1 cells. Three sesquiterpenes [kalshinoid F, 4(15)-eudesmen-1β,7,11-triol, and 4α,10α,11-trihydroxy-1βH,5βH-guai-7(8)-ene] reduced levels of TNF-α in lipopolysaccharide-stimulated THP-1 cells in a concentration-dependent manner and were more potent than dexamethasone. These natural sesquiterpenes merit further investigation as possible anti-inflammatory agents.

A Ni-catalyzed 1,2-acyl migration triggered by C–C bond cleavage was developed. The process of 1,2-acyl migration followed by olefin isomerization provides a convenient access to α,β-unsaturated ketones, which are well-known building blocks in organic synthesis. Experimental and computational studies show that the selective β-hydride elimination and Ni-hydride reinsertion play an essential role in this reaction.

Three monoterpenoid indole alkaloids (MIAs), tabernabovines A-C (1-3), were isolated from Tabernaemontana bovina. They were elucidated by spectroscopic data and computational calculations. Unlike precursors of MIAs, strictosidine and alstrostine A, alkaloid 1 consists of tryptamine and secologanin in a 2:1 ratio. Alkaloid 2 is a cage compound, and 3 possesses a bridged ring. Tabernabovine A exhibited inhibitory activity against NO production with IC50 44.1 μM compared to l-NMMA with IC50 of 48.6 μM.

The hydrogen adsorption energetics on the surface of inorganic compounds can be used to predict electrolyte stability in Li-ion batteries and catalytic activity for selective oxidation of small molecules such as H2 and CH4. Using first-principles density functional theory (DFT), the hydrogen adsorption was found to be unfavorable on high-band-gap insulators, which could be attributed to a lower energy level associated with adsorbed hydrogen relative to the bottom of the conduction band. In contrast, the hydrogen adsorption was shown to be the most favorable on metallic and semiconducting compounds, which results from an electron transfer from adsorbed hydrogen to the Fermi level or the bottom of the conduction band. Of significance, computed hydrogen adsorption energetics on insulating, semiconducting, and metallic oxides; phosphates; fluorides; and sulfides were decreased by lowering the ligand p band center, while the energy penalty for ligand vacancy formation was increased, indicative of decreased surface reducibility. A statistical regression analysis, where 16 structural and electronic parameters such as metal-ligand distance, electronegativity difference, Bader charges, bulk and surface metal and ligand band centers, band gap, ligand band width, and work function were examined, further showed that the surface ligand p band center is the most accurate single descriptor that governs the hydrogen adsorption tendency, and additional considerations of the band gap and average metal-ligand distance further reconcile the differences among compounds with different ligands/structures, whose ligand bands are different in shape and width. We discuss the implications of these findings for passivating coatings and design of catalysts and the need for novel theoretical methods to accurately estimate these quantities from first principles. These results establish a universal design principle for future high-throughput studies aiming to design electrode surfaces to minimize electrolyte oxidation by dehydrogenation in Li-ion batteries and enhance the H-H and C-H activation for selective oxidation catalysis.

DNA methylation and demethylation are the key steps in epigenetics. Emerging studies have demonstrated that these two processes play crucial roles in mammalian development and pathogenesis. Epigenetic modified cytosine and its further oxidative products, including 5-methylcytosine, 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxylcytosine, are called the "new four bases of DNA". The appearance of such new epigenetic bases can complicate DNA photodamage and repairing mechanism because they could have drastically different excited-state dynamics compared to canonical DNA nucleobases. In this study, excited-state dynamics of three demethylated nucleosides in buffer solution at physiological pH were investigated by femtosecond to microsecond time-resolved spectroscopy. Distinct excited-state dynamics are found in these demethylated nucleosides. For 2'-deoxy-5-formylcytidine (5fdCyd), direct observation of ultrafast intersystem crossing to the triple state with a 69% quantum yield is presented. Meanwhile, the triplet-state energy of 5fdCyd can transfer to the ambient molecular oxygen and generate destructive singlet oxygen. On the other hand, no such observation is seen in 2'-deoxy-5-hydroxymethylcytidine (5hmdCyd) and 2'-deoxy-5-carboxycytidine (5cadCyd), and these two bases show ultrafast internal conversion similar to that in 5-methylcytidine and cytidine. These results indicate that 5fdCyd is an effective internal triplet photosensitizer in DNA, and it could act as a new hot spot in DNA photodamage.

Four unprecedented yellow alkaloids named as taberbovines A-D (1-4) were isolated from stems of Tabernaemontana bovina Lour. Their structures were elucidated by the comprehensive spectroscopic data, computational chemistry, and X-ray crystal diffraction. Alkaloids 1-4 possessed a unique 6/6/5/6/5 ring system and were assigned to monoterpenoid quinolines. Biosynthetically, the isolated alkaloids may be derived from Aspidosperma-type alkaloid by oxidation and rearrangements. Taberbovines A-D exhibited the good inhibitory activities of formation NO in LPS induced RAW264.7 macrophages.

Molecularly imprinted polymers (MIPs) have the ability of predesigned specific recognition that can be selected to construct reliable functional materials. Combining the MIPs with magnetic nanopart...

This work describes the synthesis, structure, and physical and thermomechanical properties of fully biobased unsaturated copolyesters via melt-polycondensation of renewable monomers trans-β-hydromuconic acid and fumaric acid with 1,4-butanediol conducted by a two-step polymerization employing stannous octoate as a catalyst and 4-methoxyphenol as a radical inhibitor. The polymerization conditions, including catalyst amount, second-stage reaction temperature, and time, were optimized to prepare high molecular mass unsaturated copolyesters without isomerization and saturation reaction in the unsaturated double bonds. Consequently, a series of poly(butylene hydromuconoate-co-butylene fumarate) (PBHBF) samples with weight-average molecular weight over 80 kg/mol were obtained. The chemical structures identified by 1H and 13C NMR indicated that the notorious side reactions of isomerization and saturation of C═C bonds in unsaturated polyesters were eliminated in the obtained PBHBF copolyesters. From the physical ...

Many artificial enzymes that catalyze redox reactions have important energy, environmental, and medical applications. Native metalloenzymes use a set of redox-active amino acids and cofactors as redox centers, with a potential range between -700 and +800 mV versus standard hydrogen electrode (SHE, all reduction potentials are versus SHE). The redox potentials and the orientation of redox centers in native metalloproteins are optimal for their redox chemistry. However, the limited number and potential range of native redox centers challenge the design and optimization of novel redox chemistry in metalloenzymes. Artificial metalloenzymes use non-native redox centers and could go far beyond the natural range of redox potentials for novel redox chemistry. In addition to designing protein monomers, strategies for increasing the electron transfer rate in self-assembled protein complexes and protein-electrode or -nanomaterial interfaces will be discussed. Redox reactions in proteins occur on redox active amino acid residues (Tyr, Trp, Met, Cys, etc.) and cofactors (iron sulfur clusters, flavin, heme, etc.). The redox potential of these redox centers cover a ∼1.5 V range and is optimized for their specific functions. Despite recent progress, tuning the redox potential for amino acid residues or cofactors remains challenging. Many redox-active unnatural amino acids (UAAs) can be incorporated into protein via genetic codon expansion. Their redox potentials extend the range of physiologically relevant potentials. Indeed, installing new redox cofactors with fined-tuned redox potentials is essential for designing novel redox enzymes. By combining UAA and redox cofactor incorporation, we harnessed light energy to reduce CO2 in a fluorescent protein, mimicking photosynthetic apparatus in nature. Manipulating the position and reduction potential of redox centers inside proteins is important for optimizing the electron transfer rate and the activity of artificial enzymes. Learning from the native electron transfer complex, protein-protein interactions can be enhanced by increasing the electrostatic interaction between proteins. An artificial oxidase showed close to native enzyme activity with optimized interaction with electron transfer partner and increased electron transfer efficiency. In addition to the de novo design of protein-protein interaction, protein self-assembly methods using scaffolds, such as proliferating cell nuclear antigen, to efficiently anchor enzymes and their redox partners. The self-assembly process enhances electron transfer efficiency and enzyme activity by bringing redox centers into close proximity of each other. In addition to protein self-assembly, protein-electrode or protein-nanomaterial self-assembly can also promote efficient electron transfer from inorganic materials to enzyme active sites. Such hybrid systems combine the efficiency of enzyme reactions and the robustness of electrodes or nanomaterials, often with advantageous catalytic activities. By combining these strategies, we can not only mimic some of nature's most fascinating reactions, such as photosynthesis and aerobic respiration, but also transcend nature toward environmental, energy, and health applications.

The construction of metallosupramolecular complexes toward interesting topological structures is a critical challenge for chemists. The fluctuation in the synthetic strategy, by keeping the same metal–ligand combination, has proved a very significant approach to construct metallosupramolecular architectures. Herein, by varying the reaction conditions four new DyIII-supramolecular complexes based on a flexible dihydrazone ligand H2L (H2L = bis(2-hydroxy-3-methoxybenzylidene)adipohydrazide) in cooperation with different anions and solvents having formulas [Dy4L4(μ2-N3)2](NO3)2·6CH3OH·2H2O (1), [Dy8L8(μ2-CH3OH)4]Cl8·6CH3OH·14H2O (2), [Dy12L12(μ2-OH)2(OH)6(CH3O)2](NO3)2·2CH3OH·14H2O (3), and [Dy12L12(μ2-OH)2(NO3)2(OH)3(CH3O)](NO3)4·22H2O (4), have been successfully synthesized and their crystal structures confirmed by single crystal X-ray diffraction studies. The structural study reveals that 1 and 2 have quadruple-stranded helicate and dual triple-stranded helicate supramolecular structures, respectively, wh...

Taurine, a β-aminosulfonic acid, exerts many cellular physiological functions. It is still unknown whether taurine can regulate milk synthesis in the mammary gland. Therefore, in this study we investigated the effects and mechanism of taurine on milk synthesis in mammary epithelial cells (MECs). Bovine MECs (BMECs) cultured in FBS-free OPTI-MEMImedium were treated with taurine (0, 0.08, 0.16, 0.24, 0.32, and 0.4 mM). Taurine treatment led to increased milk protein and fat synthesis, mTOR phosphorylation, and SREBP-1c protein expression, in a dose-dependent manner, with an apparent maximum at 0.24 mM. Gene function study approaches revealed that the GPR87-PI3K-SETD1A signaling was required for taurine to increase the mTOR and SREBP-1c mRNA levels. Taurine stimulated GPR87 expression and cell membrane localization in a dose dependent manner, suggesting a sensing mechanism of GPR87 to extracellular taurine. Collectively, these data demonstrate that taurine promotes milk synthesis via the GPR87-PI3K-SETD1A signaling.

The [FeFe]-hydrogenase model, [(μ-bdt)Fe2(CO)6] (1, bdt = benzene-1,2-dithiolato), displays distinctive activity from its analogous complex, [(μ-edt)Fe2(CO)6] (2, edt = ethane-1,2-dithiolato), for electrochemical CO2 reduction in acetonitrile with methanol or water as proton source. The maximum turnover frequency of 195 s–1 estimated for 1 is more than 4800 times higher than that of 2. The influence of reaction conditions on faradaic yield and product selectivity was investigated. Controlled potential electrolysis experiments of 1 under optimal conditions gave a good faradaic yield of 88%, with formic acid as major product (selectivity ≈81%) together with a small amount of CO (selectivity ≈ 11%) and H2 (selectivity ≈ 8%). Density functional theory calculations suggest a mechanism of bimetal synergistic catalysis for electrochemical CO2 reduction by 1.

To optimize the potential window and maximize the utilization of the capacity of both negative and positive electrodes, rational design of electrode materials are critically important in full-cell construction of rechargeable batteries. In this work, we propose and fabricate a carbon-confined V2O3/Ni2P/C composite structure for excellent performance lithium ion batteries by taking advantage of the high capacity of V2O3 and low potential of Ni2P. The full cell constructed with V2O3/Ni2P/C as anode and commercial LiMn2O4 as cathode offers a record high energy density of 361.5 Wh kg–1 and excellent cycle stability, outperforming the state-of-the-art work reported in literature.

We report the synthesis and characterization of three fluoride-rich barium iron phosphates BaxFex(PO4)Fy (1 ≤ x ≤ 3, 2 ≤ y ≤ 12), which exhibited abundant structural chemistry, exhibiting diverse frameworks and connecting modes between [FeOnF6–n]m– octahedra surrounding Fe2+ or Fe3+ ions. BaFe(PO4)F2 (I) consisted of two-dimensional [Fe(PO4)F2]2– sheets built from linear ∞[Fe2O6F4]10– moieties formed by fluorine corner-sharing FeO4F2 and FeO2F4 octahedra with linking PO4 tetrahedra. Mixed-valence Ba2Fe2(PO4)F6 (II) possessed a three-dimensional framework containing Fe4O6F12 tetramers formed by the edge-sharing oxygen or fluorine atoms of cis-FeF4O2 octahedra. Ba3Fe3(PO4)F12 (III) contained one-dimensional columns of ∞[Fe3(PO4)F12]6– infinite sections built from cis-FeF4O2 and FeF5O octahedra and tetrahedral PO4 linkers. The magnetic characterization of BaxFex(PO4)Fy unveiled diverse magnetism: an S = 5/2 spin chain for (I), a weak ferrimagnet or canted antiferromagnet for (II) thanks to the presence of di...

A wide spectrum of DNA lesions can be generated from byproducts of endogenous metabolism and/or from environmental exposure. A DNA adductomic approach for the robust quantification of DNA adducts in cellular and tissue DNA may facilitate the use of DNA adducts for biomonitoring studies and enable comprehensive assessment about DNA repair. Normalized retention time (iRT) has been widely used in scheduled selected-reaction monitoring (SRM) methods for highly sensitive and high-throughput analyses of protein samples in complicated matrices. By using a similar method, we established the iRT scores for 36 modified nucleosides from the retention times of the four canonical 2'-deoxynucleosides on a nanoflow liquid chromatography-nanospray ionization-tandem mass spectrometry (nLC-NSI-MS/MS) system. The iRT scores facilitated reliable prediction of retention time and were employed for establishing a scheduled SRM method for quantitative assessment of a subset of the DNA adductome. The quantification results of the scheduled SRM method were more accurate and precise than those from an unscheduled method.

Non-apoptotic ferroptosis is of clinical importance because it offers a solution to the inevitable biocarriers of traditional apoptotic therapeutic means. Inspired by industrial electro-Fenton technology featured with electrochemical iron cycling, we construct ferrous-supply-regeneration nanoengineering to intervene tumorous iron metabolism for enhanced ferroptosis. Fe

The chemistry of confined molecules is a relatively new undertaking, and this Account describes the effects of certain host container compounds on the behavior of molecules held as guests within. The containers are known as cavitands, which have one open end that allows small molecules to go in and out. The containers are amphiphilic: they feature aromatic surfaces that create a hydrophobic space inside but their peripheries are polar and permit solubility in water. The tension between the inner space of the cavitand and the outer space of the medium is experienced by the guest molecules. Two kinds of cavitand, a cylindrical and a cone-like methylated cavitand, are presented here, and they bind guests in somewhat different depths. The cylindrical cavitand typically has its aromatic panels closer to the guests and when a suitable guest is inside, two cylindrical cavitands can form a capsule through hydrogen bonding between their rims. Halogen bonding may also occur between the aromatic faces of the cavitands and the "sigma hole" of appropriate halides. Long-chain organic compounds of suitable size form host/guest complexes through hydrophobic forces on brief sonication with both cavitands in water. The container's shape acts on flexible guests and deforms them in order to fill the space properly. NMR spectroscopy reveals that many long-chain guests assume U- or J-shaped conformations within the cavitands. The J-shaped conformations are dynamic and undergo "yo-yo" like motions in the cavitand. An inevitable consequence of a folded chain is that its ends are closer together. Accordingly, these guests are prone to cyclization processes. The cavitands act as templates and were applied as chaperones for the synthesis of several classes of large-ring heterocycles, many of which were previously unknown compounds. Functional groups that are remote in extended, long-chain molecules act independently; when folded in cavitands, the functions are brought into proximity and affect each other's reactivities. Such communication introduces the concept of "entanglement" to chemistry. The concept was applied to the monofunctionalization of symmetrical long chain diesters, diazides, and diisocyanates. For the diisocyanates, macrocyclic urea formation followed the desymmetrization. Folding flexible molecules in a predictable way can also offer new reaction pathways for remote chemical functionalization. Most such processes involving C-H activation proceed through 6-membered transition states; folding promises alternative ring sizes but has yet to be shown. These results should encourage applications using more accessible container molecules such as cyclodextrins, cucurbiturils, and pillarenes.

Developing high-performance electrode materials with high energy and long-term cycling stability is a hot topic and of great importance for sodium ion batteries (SIBs). In this work, a highly porous carbon/tin sulfide aerogel with a "skeleton/skin" morphology (SSC@SnS2) has been developed and further used as a binder-free anode for SIBs. This SSC@SnS2 electrode delivers a high specific capacity of 612 mA h g-1 at 0.1 A g-1, a good rate capability, and a long-term cycling stability up to 1000 times with an average Coulombic efficiency of ∼99.9%. Meanwhile, this SSC@SnS2 aerogel also achieves a stable cycling performance even at a high current density up to 5.0 A g-1. The fast-yet-stable sodium ion storage performance of the prepared SSC@SnS2 aerogel can be ascribed to the reasons that (i) the carbon nanofiber/graphene skeleton provides unimpeded pathways for the rapid transfer of electrons; (ii) thin SnS2 skin with nonaggregated morphology can provide a great number of active sites for sodium ion storage; (iii) the porous structure of the SSC@SnS2 aerogel ensures a rapid penetration of electrolyte and can further accommodate the volume expansion of active SnS2 nanoflakes; and (iv) the intermediate product of Na15Sn4 alloy contributes greatly to the sodium ion storage performance of the SSC@SnS2 aerogel. The excellent electrochemical performances coupling with the unique structural features of this SSC@SnS2 aerogel make it a promising anode candidate for SIBs.

Retrosynthesis is the process of recursively decomposing target molecules into available building blocks. It plays an important role in solving problems in organic synthesis planning. To automate or assist in the retrosynthesis analysis, various retrosynthesis prediction algorithms have been proposed. However, most of them are cumbersome and lack interpretability about their predictions. In this paper, we devise a novel template-free algorithm for automatic retrosynthetic expansion inspired by how chemists approach retrosynthesis prediction. Our method disassembles retrosynthesis into two steps: i) identify the potential reaction center of the target molecule through a novel graph neural network and generate intermediate synthons, and ii) generate the reactants associated with synthons via a robust reactant generation model. While outperforming the state-of-the-art baselines by a significant margin, our model also provides chemically reasonable interpretation., Comment: 17 pages, to appear in NeurIPS 2020

Three unusual sesquiterpenoid dimers, nardochinoids A–C (1–3), were isolated from Nardostachys chinensis Batal. Compound 1 features a rare fused 3,8-dioxatricyclo[7.2.1.01,6]dodecane-11-one ring system, compound 2 is the first nitrogen-containing nornardosinane–aristolane sesquiterpene conjugate, and compound 3 represents the first example of the dimer of a nornardosinane and a nardosinane sesquiterpene. Their structures were characterized by NMR spectroscopic methods and X-ray single-crystal diffraction analysis. Compound 3 showed significant anti-inflammatory activities.

Developing high energy density electrode materials is of great importance for the practical applications of lithium ion batteries (LIBs). Here, an integrated vertically aligned carbon/MoS2 aerogel (VA-C/MoS2) with oriented pores has been developed. Vertically aligned pores ensure fast transportation of electrons and rapid penetration of electrolyte, meanwhile decreasing the transfer resistance of ions in this VA-C/MoS2 anode. The good electrical conductivity of three-dimensional (3D) carbon matrix with interconnected microstructures, coupling with the homogeneously anchored MoS2 nanoflakes, promotes that all the active sites of MoS2 can be exploited during the electrochemical process. Due to these structural features of the VA-C/MoS2 aerogel, an excellent specific capacity of 1089 mAh/g, a high rate capability, and a long-term cycling stability up to 1000 cycles have been simultaneously achieved. Importantly, the areal capacity achieved by VA-C/MoS2 aerogel (12.4 mAh/cm2) based on a high mass loading of M...

The electrochemical CO2 reduction reaction (CO2RR) is a promising approach for converting fossil fuel emissions into environmentally sustainable chemicals and fuels. The ability to control the surf...

Surface-supported metal-organic framework (MOF) films hold fantastic promises for viable scientific applications, particularly in sensors and electronic devices. However, slow diffusion, limited mass transfer, and low conductivity hinder the industrial application of MOFs. Herein, we propose a rime-inspired MOF film based on a kind of beautiful natural landscape. To mimic rime architecture, we compare and conclude the intrinsic similarity between natural biomineralization and electrochemical self-assembly of MOFs and used an anodic-induced approach to producing rime-structured MOF architecture. Interestingly, the MOF film with space-filling macro-meso-micropores exhibits remarkable electrochemical sensing performances for simultaneous determination of lactate and glucose, including high sensitivity, excellent selectivity, and a wide linear range in a wide range of pH values. Moreover, this rime-inspired system is able to be applied as a biofunctional human perspiration sensing platform. Our work opens a new horizon for poring on biomimetic rime concept to explore specifically structured MOFs with more diverse functionalities.

Recently, great attention has been spent in the exploitation of stable and highly efficient nonprecious metal-based catalysts that can be applied to energy conversion techniques by electrocatalytic reaction. Transition metal phosphides (TMPs) are promising and intriguing candidates for the hydrogen evolution reaction (HER) as well as other energy conversion technologies. Here we present a facile sol–gel route aimed at synthesizing FeP nanocrystals embedded in N-doped carbon nanosheets (FeP/NCNSs). The obtained nanocomposite exhibits excellent hydrogen generation activity, achieving 10 mA cm–2 at relatively low overpotential (114 mV) in acidic electrolyte (0.5 M H2SO4). In the respect of structural integrity, the N-doped carbon layer could protect the FeP nanocrystals from acidic degradation, thus endowing the hybrid with superior durability to the bare FeP nanoparticles during long-term operation. Furthermore, the as-synthesized electrocatalyst also exhibits high catalytic activity and remarkable cyclabil...

Recently, porous framework materials with various network-type structures have been constructed via several different approaches, such as coordination interactions, reversible covalent bonds, and non-covalent interactions. Here, we have combined the concepts of supramolecular coordination complex (SCC) and metal-organic framework (MOF) to offer a new strategy to construct a diamondoid supramolecular coordination framework (SCF) from an adamantanoid supramolecular coordination cage as the tetrahedral node and a difunctional Pt(II) ligand as the linear linker via the stepwise orientation-induced supramolecular coordination. The adamantanoid supramolecular coordination cage has four uncoordinated pyridyl groups, which serve as the four vertexes of the tetrahedral geometry in the diamondoid framework. As a result, this diamondoid SCF exhibits an adamantanoid-to-adamantanoid substructure with two sets of pores including the interior cavity of the adamantanoid cage and the extended adamantanoid space in between the individual cages in the framework. In addition, the shape-controllable and highly-ordered self-assembly of nanometer-sized diamondoid SCF is observed as micrometer-sized regular octahedrons by evaporation under heating in DMSO. This study demonstrates the potential application of supramolecular coordination complexes in the precise construction of highly-regulated porous framework materials.

Electrochemical precipitation has obtained great attentions for water softening in recent years. In order to avoid cathode deactivation, periodical scale detachment is essential. In general, the scale adhered to the cathode is detached by mechanical scraping. Although mechanical scraping is easy operated, elastic scraper must be installed between electrodes, leading to the low softening efficiency and high energy consumption. To overcome such a problem, a new current pulsated electrochemical precipitation process was proposed in this paper. Scale detachment was accomplished by increasing the current density significantly. Experimental results showed that the both high softening and detachment performance were achieved. The precipitation rate was as high as 40.47 g/h/m2. The energy consumption and the total hardness removal efficiency were 8.9–13.2 kWh/kg CaCO3 and 17.8–22.8%, respectively. Repetitive experimental results indicated the current pulsated electrochemical precipitation process could run steadi...

Porous SnO2@C@VO2 composite hollow nanospheres were ingeniously constructed through the combination of layer-by-layer deposition and redox reaction. Moreover, to optimize the electrochemical properties, SnO2@C@VO2 composite hollow nanospheres with different contents of the external VO2 were also studied. On the one hand, the elastic and conductive carbon as interlayer in the SnO2@C@VO2 composite can not only buffer the huge volume variation during repetitive cycling but also effectively improve electronic conductivity and enhance the utilizing rate of SnO2 and VO2 with high theoretical capacity. On the other hand, hollow nanostructures of the composite can be consolidated by the multilayered nanocomponents, resulting in outstanding cyclic stability. In virtue of the above synergetic contribution from individual components, SnO2@C@VO2 composite hollow nanospheres exhibit a large initial discharge capacity (1305.6 mAhg–1) and outstanding cyclic stability (765.1 mAhg–1 after 100 cycles). This design of compo...