Search

Surface enhanced Raman spectroscopy (SERS) is a promising sensing technique that can provide unique chemical and structural fingerprint information, but gaining reliable SERS quantitative data with high sensitivity and stability still remains a challenge. Although using a molecule as an internal standard (IS) can improve the SERS quantitative capability, the reliability and SERS measuring conditions for signal fluctuations during calibration based on IS are yet to be explored when the embedded IS molecules and target objects are located in different environments. Herein, a 3D hotspot matrix SERS platform based on Au@4-MPy@AgNPs was constructed in water with the assistance of glycerol and the dynamic signal changes from the IS, i.e. 4-Mpy, and target molecules were monitored during the process of evaporation with high sensitivity and stability. In contrast to the traditional water-dispersed drying film system, the variation trends of IS and target molecules were consistent in the glycerol-assisted liquid film protection system. Therefore, it is reasonable to calibrate the signal fluctuation by utilizing the embedded IS based on the construction strategy of a glycerol-assisted 3D hotspot platform. This work demonstrates a rational, reliable and precise SERS quantitative technique for testing analyte concentrations in practical systems and has great application prospects in the field of analytical chemistry.

Establishing a fast and effective extraction method for herbs is beneficial for the determination of their main compounds and estimating their quality. In this study, deep eutectic solvents (DESs) were optimized to simultaneously extract three main types of phenolic acids, i.e., regaloside B, regaloside C, and regaloside E, and polysaccharides from the bulbs of Lilium lancifolium Thunb. Based on the optimized extraction conditions, i.e., an extraction temperature of 50 °C, an extraction time of 40 min, a solid–liquid ratio of 1 : 25, and a ratio of water in the DES of 20%, the extracted amounts of regaloside B, regaloside C, and regaloside E reached 0.31 ± 0.06 mg g−1, 0.29 ± 0.03 mg g−1, and 3.04 ± 0.38 mg g−1, respectively. The extraction efficiencies were higher than those obtained using conventional organic solvents. Next, the polysaccharide levels were measured and compared with those obtained using a conventional hot water extraction method, and equivalent extraction efficiencies were obtained with the conventional hot water extraction method. This study provides a new application of deep eutectic solvents (DESs) for simultaneously extracting phenolic acids and polysaccharides from the bulbs of L. lancifolium Thunb. Considering the biodegradability and pharmaceutical acceptability, DESs as a class of green solvents could have wide applications in the extraction of natural products.

P2-type Na2/3Ni1/3Mn2/3O2 is one of the most promising cathode candidates for sodium-ion batteries due to its high specific capacity and high working voltage. However, a detrimental P2–O2 phase transition usually occurs at a high voltage (>4.2 V) leading to poor cycle stability. Herein, we propose to mitigate this critical issue through a controlled F−/Ca2+ dual-doping strategy with CaF2 as a dopant. The divalent Ca2+ ion doped in the Na layer stabilizes the layered structure at a high voltage when excessive Na+ is extracted. The more electronegative F− ion forms a stronger transition metal (TM)–F bond and reduces the electrostatic repulsion between the oxygen layers impeding the gliding of TMO2 layers. The Ca2+/F− co-doping successfully suppresses the unfavorable P2–O2 phase transition, and significantly improves the structural stability and cycling performance (27.1% vs. 87.2% after 500 cycles at 1C). Furthermore, density functional theory calculations combined with experimental tests reveal that the incorporation of Ca2+ and F− in Na sites and O sites facilitates the electronic and ionic conductivity owing to Na+/vacancy disordering, which enhances the high-rate capability. This study provides some insights into the design of long-life and high-rate cathode materials for sodium-ion batteries.

Fluorophores with photo-modulatory fluorescence properties are valuable for cutting-edge localization microscopy. The existing probes are either photo-activatable, or photo-switchable, but not both. We report a probe (DH-SiR), a leuco-dye obtained by reduction of Si-rhodamine, with both photo-activatable and photo-switchable fluorescence. The potential for super-resolution microscopy was showcased.

The water–gas shift (WGS) reaction is a key chemical process for CO removal and hydrogen generation in which CO and H2O are converted to CO2 and H2. The activation of H2O at the oxygen vacancy sites of a reducible oxide-supported catalyst is widely viewed as the critical step for this reaction. However, the strategy of rational fabrication of oxygen vacancies in reducible oxides to boost catalytic activity is rarely reported. Here, we report a facile method to fabricate oxygen vacancies through assembling an amorphous titanate overlayer on the surface of TiO2 support via alkali doping, aiming to improve its activity in WGS reaction. TEM, EPR, H2-TPR and XPS results verified that the titanate overlayer is in situ formed via alkali doping, where oxygen vacancies can be rationally regulated during reduction through tuning the amount of alkali. The ease of oxygen vacancy formation induced by alkali doping could be attributed to the lower Ti–O bond energy in titanate. It is shown that sodium-doped Ni/TiO2 with titanate overlayer on the support exhibited superior activity in WGS reaction compared with undoped catalyst, i.e., around threefold greater activity compared with undoped catalyst was achieved at 300 °C. Furthermore, the formation of CH4, a common side reaction in WGS on Ni-based catalysts, is suppressed on the sodium-doped Ni/TiO2. More importantly, the titanate overlayer strategy is successfully extended to other reducible oxide-supported catalysts, which provides a universal method to fabricate oxygen vacancies in reducible oxide-supported catalysts.

We disclose a transition-metal-free decarbonylative alkylation reaction for the synthesis of N-aryl α-hydroxy amides via precise cleavages and reorganizations of three C–C σ bonds. For the first time, a medium-sized cycloalkyl was used as a leaving group to initiate the decarbonylative alkylation process. We also demonstrate the concept of “one-pot” inert C–C bond activation/deuteration. This strategy allows the formation of α,β-deuterated hydroxyamides by using DMSO-d6 as a solvent.

Flow battery technology offers a promising low-cost option for stationary energy storage applications. Aqueous zinc–nickel battery chemistry is intrinsically safer than non-aqueous battery chemistry (e.g. lithium-based batteries) and offers comparable energy density. In this work, we show how combining high power density and low-yield stress electrodes can minimize energy loss due to pumping, and have demonstrate methods to achieve high energy and power density for ZnO/Ni(OH)2 electrodes by changing composition and optimizing testing protocols. Firstly, mechanically stable and homogeneous Ni(OH)2/carbon and ZnO/Zn flowable electrodes in 7 M KOH electrolyte were designed using a microgel dispersion as the suspending matrix. By determining the critical volume fractions for conductivity percolation, colloidal suspensions with 6.2 vol% of carbon and 23.1 vol% of Zn were selected for preparing catholytes and anolytes to ensure that these semi-solid electrodes possess high voltage and high coulombic efficiencies. The resulting flowable electrodes exhibited non-Newtonian rheology with a yield stress of approximately ∼200 Pa, which assists in maintaining mechanical stability of the suspensions. An energy density of up to 134 W h Lcatholyte−1 and power density up to ∼159 mW cmgeo.−2 was demonstrated for semi-solid ZnO/Ni(OH)2 electrodes, and coulombic efficiency of 94% was achieved during cycling by optimizing the charging protocol to 60% SOC of Ni(OH)2. Lastly, semi-solid ZnO and Ni(OH)2 flow cells were built and tested using an intermittent mode of operation. The high energy and power densities, high coulombic efficiency, and negligible pumping loss of the Zn–Ni semi-solid electrodes developed in the present work present a promising system for further development.

Twelve undescribed bisindole alkaloids, tabernaemontines A–L, were simultaneously isolated from the leaves of Tabernaemontana bovina and their structures were elucidated by spectroscopic methods. All alkaloids consist of two Aspidosperma-type units with various intramolecular linkages. Particularly, tabernaemontines A–D were assembled through C-3/14′ with a large angle strain, whilst tabernaemontines E–K adopted a preferential conformation. Tabernaemontine L was assembled via a C-14/10′ connection. Tabernaemontines F, K and L showed good inhibition of microglial activation. As a representative of Aspidosperma-type dimers, the P38 MAPK activation inhibition properties of tabernaemontine F were tested. The promising results revealed this compound as a potential candidate for the treatment of chronic neurodegenerative diseases.

The self-assembled, hydrogen-bonded hexameric resorcin[4]arene capsule represents one of the most readily accessible host systems for the study of container catalysis. This assembly can stabilize cationic intermediates and transition states through cation-π interactions with the aromatic walls and several reactions have been successfully performed in its cavity. This highlight focuses mainly on the applications of this host system for the catalysis of cyclization reactions such as terpene cyclizations, intramolecular hydroalkoxylation and carbonyl-olefin metathesis.

A microwave assisted extraction technology was used to extract chrysophanol from rhubarb. The present study will focus on the optimum extraction conditions of chrysophanol and discuss the inhibitory effect of chrysophanol on the biofilm formation of Streptococcus suis (S. suis). A Box–Behnken design based on single-factor experiments was applied to optimize the microwave assisted extraction process and to study the factors' relationships with each other. The results showed that a microwave temperature of 56 °C, ethanol concentration of 70%, microwave power of 540 W and liquid to raw material ratio of 55 mL g−1 were the optimal conditions for the microwave method. The yield of chrysophanol was 2.54 ± 0.07% under the optimal conditions, which was in agreement with the predicted value (2.64%). Then, the chemical structure of the extracted chrysophanol was identified by LC-MS. In addition, in vitro experiments showed that chrysophanol has an inhibitory effect on S. suis (minimum inhibitory concentration was 1.98 μg mL−1) and was shown to significantly inhibit the capability of S. suis to form a biofilm using crystal violet staining. Finally, scanning electron microscopy analysis showed that the three-dimensional structure of the biofilm deposited by the S. suis community was destroyed by chrysophanol.

Lonimacranaldes A and B (1 and 2), along with one biogenetically related intermediate, lonimacranalde C (3), were isolated from the flower buds of Lonicera macranthoides. Characterized by an iridoid structure and an additional C-6 unit with an aldehyde group, compounds 1 and 2 are the first examples of hybrid iridoids possessing an unexpected 6/5/6 fused tricyclic ring system, while compound 3 serves as an important precursor for their generation. The structures of lonimacranaldes A–C (1–3) were revealed by extensive spectroscopic and X-ray diffraction analyses. A plausible biogenetic pathway for them was proposed. Compound 3 showed anti-inflammatory activities by inhibiting the production of IL-6 on LPS-induced RAW 264.7 cells with an IC50 value of 6.33 μM.

A new water-soluble cavitand was synthesized which showed isomeric conformations in different solvents. The cavitand displayed multiple conformations – vase, kite, velcrand and intermediate shapes – in CD3OD. The binding properties with hydrophobic (cycloalkanes) and amphiphilic (cycloalkyl carboxylic acids) guests in D2O indicated a deep aromatic pocket.

Theoretical calculations have been performed to gain deeper understanding on the mechanism of Cp*Co(III)-catalysed C(sp3)–H amination of 8-methylquinoline with phenyl-1,4,2-dioxazol-5-one. The result suggests that the additive AgSbF6 could thermodynamically facilitate the generation of catalytically active species Cp*Co(OPiv)+. The subsequent catalytic cycle involves sequential external base assisted C(sp3)–H activation, decarboxylation, nitrene insertion, and protonation. Importantly, a remarkable “two-state reactivity” scenario was disclosed for this reaction. A distinct multi-reference feature was found in the processes for Co-nitrene radical intermediate and C–N bond formations, which thus greatly enriches the cobalt catalysis chemistry. Such a multi-reference character was the outcome of double excitation from the Co–N π-bonding orbital to its antibonding orbital. DFT results indicate that aminating reagents with a rigid structure would be preferred because they form strong orbital interaction with the metal center. In addition, it is theoretically predicted that the Fe(III) species is a promising candidate for efficient C(sp3)–H activation and Tp (Tp = hydridotris(pyrazolyl)borate) can serve as a more effective ligand for Co(III) catalysed C(sp3)–H activation, thanks to its stronger interaction with the Co center which thus stabilizes the transition state.

Water-soluble host molecules offer a range of environments to their guests. Polar functions of guests are exposed to the medium while hydrophobic groups are generally buried in the containers and hidden from reagents in solution. Here, we apply these preferences to convert α,ω-dienes to epoxy alkenes using cavitands as reaction vessels. Reaction of one end of a diene with NBS in water gives a bromohydrin that binds in the cavitand with the hydroxyl exposed and the remaining alkene buried. Treatment with base converts the bromohydrin to an epoxide. The reaction sequence provided up to 84% yields of monoepoxides from symmetrical dienes separated by 4 to 10 methylene groups. With 1,4-diisopropenyl benzene, a nearly quantitative yield of the monoepoxide was obtained. The application should be general for converting symmetrical hydrophobic guests to unsymmetrical, amphiphilic ones.

The contamination of chlorophenols in water has been considered as an urgent environmental issue. In this study, two polar photocatalysts with a similar structure, K3B6O10Br (KBB) and K3B6O10Cl (KBC) were synthesized through a high temperature solid phase method and applied for the effective mineralization and removal of the chlorophenols. More than 92.0% of 2-chlorophenols can be fully degraded within 16 min under UV light irradiation, which is six times faster than the commercial P25 TiO2 catalyst. The out-of-center distortions capability of the XK6 octahedrons is greatly influenced by X (X = Cl and Br) atoms. The magnitude of the out-of-center distortion of KBC and KBB were 0.137 and 0.027, respectively. A better photocatalytic activity performance was therefore observed for KBC due to its higher spontaneous polarization ability and facile charge separation process. Kelvin probe force microscopy (KPFM) experiments further proved KBC has a larger surface potential change before and after the light irradiation. Reactive species capture experiments confirmed the role of radicals in the order of ˙O2− > e− > h+ > ˙OH.

Bismuth scandate-lead titanate (abbreviated as BS–PT) ceramics are a promising piezoelectric material for high temperature applications because of their excellent piezoelectric performance as well as high Curie temperature. The piezoelectric properties of ferroelectric materials are closely related to the microscopic domain structure; however, quantitative analysis on domain evolution as well as its effect on materials properties in both electric poling and thermal depoling processes is seldom revealed. In this work, we investigate the effects of electric poling and thermal depoling on the domain structure and piezoelectric performance in tetragonal BS–PT ceramics. Based on an early study by Uchida and Ikeda, a modified model is developed to quantitatively study both 180° and 90° domain reversals during the electric poling process. To obtain a clear correlation between the domain structure and piezoelectric properties, quantitative estimation of 90° domain reversal in both electric poling and thermal depoling processes is done by an XRD method. The present work provides a comprehensive insight into domain evolution of tetragonal BS–PT ceramics, which is also of heuristic significance to other perovskite piezoelectric ceramics.

A novel catalytic Fenton system based on H2 and the solid catalyst Pd/MIL-101(Cr) (MHACF-MIL-101(Cr)) was developed at normal temperature and pressure. In this system, the reduction process of FeIII back to FeII was accelerated significantly. Using only trace levels of FeII at the beginning of the reaction, MHACF-MIL-101(Cr) provided continuous production of hydroxyl radicals and rapid degradation of the model contaminant 4-chlorophenol (10 mg L−1) under the initial conditions of pH 3, 25 μM FeII, 25 mM H2O2, 85 mL min−1 H2 and 2 g L−1 Pd/MIL-101(Cr). The activity of the solid catalyst gradually decreased from 100% to about 70% after 6 consecutive degradation reaction cycles of 18 h. This may mainly be attributed to the structural damage and the surface area reduction of this catalyst.

Surface-enhanced Raman spectroscopy (SERS) has been one of the most promising analytical tools. Despite many efforts in the design of SERS substrates, it remains a great challenge for creating a general flexible substrate that could in situ detect analytes on diverse objects. Herein, we report our attempt to address this issue by developing a facile and versatile method capable of generating silver/gold nanoparticles in situ on the surface of a cellulose acetate (CA) polymer in a simple, cheap, practical, and capping agent-free way. The as-prepared substrates exhibit excellent sensitivity, which enabled detection of Rhodamine 6G at concentrations as low as 10−12 M. Taking advantage of the excellent flexibility and optical transparency of the CA matrix, the highly SERS-active substrate was applied for in situ identification and detection of pesticide residues on fruits. The results indicated that tetramethylthiuram disulfide (TMTD) and thiabendazole (TBZ) can be clearly identified at concentrations as low as 18.05 ng cm−2 and 15.1 ng cm−2, respectively, which were much lower than the maximum permitted residue doses with respect to food safety.

In this research, the crystal structure of antidiabetic drug gliquidone (GQD) is analysed and multicomponent crystals such as piperazine (PPZ) salt and eutectics are designed and synthesized based on its structural features. Three polymorphs of the salt are obtained together with five solvates. Fortunately, four single crystals of the salts are determined for the first time. The results reveal that the high hydrogen bond-forming ability of PPZ plays a vital role in breaking the original packing of GQD and resulting in salts instead of eutectics. Finally, comprehensive characterization of the salt polymorphs is performed and the result shows that the powder properties and powder dissolution are enhanced by the salt formation compared with the parent form.

Even though several stretchable electrochromic (EC) materials have been reported, effective and facile strategies for the development of ideal intrinsically stretchable EC materials with various colors, simple preparation, low energy consumption, excellent performance, and practicability are still urgently required. Herein, an ideal inherently stretchable EC device is demonstrated and constructed by combining a novel intrinsically stretchable EC material as well as new asymmetric stretchable conductive electrodes where Ag nanowires are used as the cathode and Au nanosheets are used as the anode in order to balance the conductivity, transmittance, stability, and mechanical properties. A stretchable EC material containing a highly transparent, elastic, and conductive polyacrylamide (PAAM) hydrogel and some new water-soluble EC molecules exhibits easily selectable multicolor-tunable property, desirable coloration efficiency with low energy consumption, and health- and environment-friendly characteristics. Further, color changes in the device can be easily and reversibly manipulated in seconds from yellow to red or brown under tensile strain. These promising results reveal that this new method/process is easily applicable and has promising potential for future wearable electronic displays.

Two new tetracationic cyclophanes 1 and 2 containing tetraphenylethene and bipyridinium moieties were synthesized via a two-step SN2 reaction. These water-soluble cyclophanes with a cationic and hydrophobic cavity exhibited selective recognition for amino acids (e.g. tryptophan) and adenosine derivatives (e.g. ATP) via electrostatic and π-π interactions in water.

Novel Nb-doped Bi2WO6 nanosheets have been successfully synthesized by a simple hydrothermal method. XRD, Raman spectra, XPS and SEM were adopted to analyze the structure and morphology of the samples, then the structure-dependent optical properties, photoelectric behavior and photocatalytic activities were investigated, and the structure–property relationship was also discussed. The results show that doping Nb5+ can increase the oxygen vacancies in the Bi2WO6 lattice and reduce the optical band gap of Bi2WO6. The oxygen vacancies also act as electron traps, which promote the separation of photogenerated carriers. Hence, compared with the pure Bi2WO6, the as-prepared Nb-doped Bi2WO6 nanosheets exhibit enhanced visible-light photocatalytic activity for removing contaminants in water such as rhodamine B and tetracycline.

An oxidative cross-dehydrogenative coupling of BODIPYs with toluene and its derivatives has been developed, allowing for the facile synthesis of a broad range of structurally diverse α-benzylated BODIPYs. The method exhibits excellent chemoselectivity, affording exclusively α-benzylated BODIPYs in the presence of t-BuOOH and a catalytic amount of Cu(OAc)2. The direct use of readily available toluene and its derivatives as coupling partners avoids unproductive steps for preactivating the functional group installation, and is therefore attractive. Most of the resulting dyes are highly emissive in the solid state due to the introduction of bulky benzyl groups onto the BODIPY core.

Rational design of amyloid-based materials requires structural insight into such materials. Here, we explore the use of a side-chain-based infrared (IR) probe technique combined with atomic force microscopy, Raman spectroscopy, UV-Vis spectroscopy, and thermogravimetric analysis coupled with mass spectrometry to elucidate the structural details of an amyloid nanosheet formed by an Aβ(16-22) variant, KLVXFAK, where X is p-cyanophenylalanine with its side-chain cyano group being an IR probe. Through the structural constraints obtained with the combined tools, we are able to propose a novel structural model for the amyloid nanosheet. The nanosheet can be viewed as a stack of class 7-type steric-zipper-like amyloid structures with a unique sheared intersheet arrangement: the β-sheets are stacked along a zippering axis with each individual β-sheet sheared relative to its adjacent β-sheets by two residues through the cyano-lysine intersheet hydrogen bond. With such a configuration, the side view of the nanosheet is similar to that of a stack of tilted-aligned roof tiles with each individual β-sheet being each tile. In addition, this work provides a nice example of how to utilize the side-chain-based IR probe technique combined with other supplemental tools to build a hierarchical structural model for a complex amyloid assembly.

Drug-induced liver injury (DILI) is a serious concern in modern medicine due to its unpredictability. Currently, biochemical serum markers are being used in DILI detection. However, these biomarker-based methods lack sensitivity and specificity. A high intracellular level of hydroxyl radicals (˙OH) has been regarded as an early indicator of DILI. Therefore, we proposed an ˙OH-responsive and hepatocyte-targeted nanoprobe via conjugation of carboxyfluorescein-labeled DNA and pegylated galactose on the surface of gold nanoparticles. The nanoprobe could bind to a hepatocyte-specific asialoglycoprotein receptor through galactose, and it could be internalized into liver cells. In the presence of high levels of ˙OH in DILI, the DNA could be cleaved to release carboxyfluorescein, leading to remarkable fluorescence enhancement for ˙OH detection. Confocal fluorescence imaging demonstrated that the nanoprobe could be successfully applied in monitoring high ˙OH levels resulting from acetaminophen or triptolide-induced liver injury, which may provide a simple but powerful protocol for the prediction of DILI.

We present a comprehensive molecular dynamics (MD) simulation study of composition-structure trends in a set of 25 glasses of widely spanning compositions from the following four systems of increasing complexity: Na2O-B2O3, Na2O-B2O3-SiO2, Na2O-CaO-SiO2-P2O5, and Na2O-CaO-B2O3-SiO2-P2O5. The simulations involved new B-O and P-O potential parameters developed within the polarizable shell-model framework, thereby combining the beneficial features of an overall high accuracy and excellent transferability among different glass systems and compositions: this was confirmed by the good accordance with experimental data on the relative BO3/BO4 populations in borate and boro(phospho)silicate networks, as well as with the orthophosphate fractions in bioactive (boro)phosphosilicate glasses, which is believed to strongly influence their bone-bonding properties. The bearing of the simulated melt-cooling rate on the borate/phosphate speciations is discussed. Each local {BO3, BO4, SiO4, PO4} coordination environment remained independent of the precise set of co-existing network formers, while all trends observed in bond-lengths/angles mainly reflected the glass-network polymerization, i.e., the relative amounts of bridging oxygen (BO) and non-bridging oxygen (NBO) species. The structural roles of the Na+/Ca2+ cations were also probed, targeting their local coordination environments and their relative preferences to associate with the various borate, silicate, and phosphate moieties. We evaluate and discuss the common classification of alkali/alkaline-earth metal ions as charge-compensators of either BO4 tetrahedra or NBO anions in borosilicate glasses, also encompassing the less explored NBO-rich regime: the Na+/Ca2+ cations mainly associate with BO/NBO species of SiO4/BO3 groups, with significant relative Na-BO4 contacts only observed in B-rich glass networks devoid of NBO species, whereas NBO-rich glass networks also reveal substantial amounts of NBO-bearing BO4 tetrahedra.

A thermally induced novel formal [4+2] cycloaddition of cyclobutenones with electron-deficient alkynes under metal-free conditions has been developed for the first time. The reaction can proceed in a highly regioselective manner and provides a straightforward and efficient method for the synthesis of 4-pyridone derivatives from readily available starting materials in a single step.

A unique coordination polymer of Au(I)–thiolate has been used as a model system to study the molecular-level pseudopolymorphism in hierarchical assemblies and help understand the environment acclimation of biomacromolecules. Two lamellar pseudopolymorphs of the coordination polymer Au(I)–3-mercaptopropionic acid (MPA) have been successfully prepared in two solvents, water and ethylene glycol (EG), at appropriate pH values. The two pseudopolymorphs have distinct differences in optical properties, morphology and thermal stability. By analyzing their composition and structure in detail, it is suggested that the large change in the dissociation ability of –COOH and –COONa species in MPA ligands plays an important role in enabling the solvent-induced pseudopolymorphism. Based on the above conclusion, a series of water/EG binary solvents and pH values have been used to induce the formation of other possible polymorphs, and a third pseudopolymorph has been discovered. However, it cannot be separated from the above two polymorphs. The two obtained pseudopolymorphs exhibit high structure preservation and cannot inter-convert to each other either in solution or in the solid state because of the collective interactions. Based on the above results and other studies, reflections on how biomacromolecules realize the environment acclimation chemically are finally discussed.

A novel Z-scheme core–shell g-C3N4/MCNTs/BiOI heterojunction was successfully designed and fabricated through filling multi-walled carbon nanotubes (MCNTs) with g-C3N4, followed by the loading of BiOI on the outer surface of the MCNTs. The structure–property relationship was analyzed by X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (DRS), photoluminescence spectra (PL), ESR probe tests and reactive species trapping measurements. The results show that the BiOI nanoparticles are uniformly loaded on the surface of the MCNTs which are fully filled by g-C3N4. The MCNTs connect the two semiconductors of g-C3N4 and BiOI, and serve as electron mediating conductors to promote the transfer of the photo-generated electrons, thereby constructing a Z-scheme heterojunction between g-C3N4 and BiOI. With this unique structure, enhanced visible-light photocatalytic activities are achieved because of the synergistic effect of light harvesting and improved separation efficiency of photo-generated carriers.

For conventional ferromagnetic systems, the magnetocaloric effect (MCE) is dominated by the entropy changes upon magnetic phase transitions. For strongly correlated oxides such as manganites, in which competing magnetic orders coexist and respond to an external field differently, the MCE is more complex due to the electronic phase separation (EPS) phenomenon. Taking the well-known (La2/3Pr1/3)5/8Ca3/8MnO3 (LPCMO) manganite as a model system, we investigated how the length scale of EPS phases affects the MCE. Specifically, the EPS length scale can be dramatically reduced by the spatial ordering of Pr dopants in the LPCMO system. Experimental results indicate that the magnetic entropy change of the Pr-ordered LPCMO is considerably larger than that of the Pr-random LPCMO by a factor up to six at the onset temperature of the ferromagnetic phase. A direct relation between the length scale of EPS and MCE has been established based on the experimental results.

A copper-catalyzed peri-selective direct C–H sulfenylation of 1-naphthylamines with disulfides was developed. This protocol employs inexpensive Cu(OAc)2 as the catalyst, air as the terminal oxidant, and readily available diaryl (or dialkyl) disulfide and diselenide as chalcogenation reagents. High functional group tolerance and excellent regioselectivity were demonstrated by the efficient preparation of a wide range of 8-sulfenyl-1-naphthylamines.

Ascorbic acid (AA), which is a well-known antioxidant, reacts with reactive oxygen species (ROS) inside the human body. It is crucial for the proper functioning of living organisms, however, the sensing of AA is still a huge challenge. Herein, a mixed Ce/Eu metal–organic framework [ZJU-136-Ce1−xEux (x = 0.24, 0.36)] is designed and synthesized. Due to the specific redox reaction between the enediol group of AA and Ce4+, the fluorescence intensity of the ligand increases significantly with a simultaneous fluorescence quenching of Eu ions, resulting in a ratiometric fluorescent probe for detecting AA. It is worth noting that the ZJU-136-Ce1−xEux (x = 0.24, 0.36) exhibited good luminescence properties and ratiometric fluorescence for AA determination. Furthermore, the regeneration cycle test shows that the mixed Ce/Eu metal–organic framework can be used as a potential ratiometric sensor for AA determination.

Molybdenum carbides are considered as one type of privileged noble-metal-free electrocatalysts for hydrogen evolution reactions (HER) due to their d-band electron structure, which is similar to Pt. Especially, the electronic structure of such materials can be further adjusted by elemental doping to improve their electrocatalytic activity. Herein, we selected the Anderson-type polyoxometalates (POMs) (NH4)n[TMMo6O24H6]·5H2O (TM = Ni2+, Co2+, n = 4; TM = Fe3+, Cr3+, n = 3) as precursors to prepare new transition-metal-doped Mo2C materials. When these POMs were mixed with dicyandiamide (DCA) by solid grinding, and carbonized at a high temperature, a series of Ni-, Co-, Fe-, and Cr-doped Mo2C composite nanoparticles covered by few-layer graphitic carbon shells (abbr. TM-Mo2C@C) were obtained. All these nanoparticles possess a similar size, morphology, and TM/Mo component ratio, and thus it is feasible to systematically investigate the influence of different TM dopants on the electrocatalytic activity of Mo2C for HER. Both electrocatalytic experiments and DFT calculations reveal that TM dopants have a significant effect on the hydrogen binding energy (ΔGH*) and the catalytic activity of Mo2C. The sequence of HER electrocatalytic activity is as follows: Ni-Mo2C > Co-Mo2C > Fe-Mo2C > Cr-Mo2C. As a result, Ni-Mo2C@C possesses the best HER performance, which required an overpotential of 72 mV at a current density of 10 mA cm-2 and the Tafel slope is 65.8 mV dec-1. This work suggests a shortcut to reasonably investigate the effects of elemental doping on molybdenum carbides and explore new high-efficient and low-cost electrocatalysts for HER.

Noble metal loading and semiconductor compositing are two effective techniques to improve the photocatalytic activity of semiconductor photocatalysts. These two tactics are combined herein to achieve hierarchical Ag@TiO2@ZnO nanowires, which consist of ZnO nanorods growing radially from Ag nanowires with the help of a compact TiO2 intermediate layer. The Ag@TiO2@ZnO nanowires consisted of 4.3 wt% Ag, 16.7 wt% TiO2 and 79.0 wt% ZnO. When utilized to assist photodegradation of phenol in water under UV light illumination, the nanowires exhibited a reaction rate constant 1.8 times that of commercial Degussa P25 TiO2 nanoparticles and 3.8 times that of commercial ZnO nanoparticles. The excellent photocatalytic activity can be contributed to the enhanced light adsorption and charge separations arising from both Ag/TiO2 Schottky barriers and TiO2/ZnO heterojunctions.

The influence of silk fibroin (SF) and magnesium ions (Mg2+) on calcium carbonate (CaCO3) bio-mineralization has been investigated. However, the morphology of CaCO3 controlled by the synergistic effect of SF and magnesium ions has not been reported in microbial mineralization systems. Here, we provide novel experimental insights into the role of SF and Mg2+ in the crystallization of CaCO3 in microbial mineralization systems. The morphology and crystallization of CaCO3 aggregates are affected by the self-assembly of SF molecules and the inhibition of Mg2+. This combination promoted the growth of a novel, rod-like superstructure of calcite crystals by aggregating/assembling behavior and crystallization kinetics. In addition, prism-shaped and hemispherical CaCO3 crystal superstructures were obtained in the presence of Mg2+ and SF, respectively. Furthermore, CaCO3 crystals with well-defined morphologies and polymorphs can be obtained by regulating the crystallization conditions (mineralization time and the amount of the additives). The above system has potential applications in the design and preparation of numerous inorganic materials with novel morphologies and specific textures.

Strontium titanate (SrTiO3) is a promising n-type thermoelectric material at high temperature. However, to date, its reported high dimensional figure of merit (zT) > 0.4 has only been achieved in a narrow temperature range near 1000 K. In this study, zT values of >0.4 were achieved in the broad temperature range of 769–1009 K in bulk SrTiO3 co-doped with La and Nb with in situ precipitation of second phases of NbC and TiO2−δ. The electronic transport properties of the samples were optimized by adjusting the doping ratio, resulting in a large power factor of 1.82 mW m−1 K−2 at 622 K for 7 mol% La–7 mol% Nb-doped SrTiO3. Notably, the power factor (PF) decreased more gradually with increasing temperature, resulting in a high PF of 1.28 mW m−1 K−2 even at 1009 K. In addition, precipitation of the second phases occurred during sintering of the mixture of La–Nb doped SrTiO3 nano powder and carbon powder, which provided additional phonon scattering centers except for the phonon scattering centers of La and Nb point defects. This high thermoelectric performance achieved over a broad temperature range could be beneficial for broadening the range of application temperatures for bulk polycrystalline SrTiO3. Furthermore, the tailoring strategy of co-doping, an in situ second phase, and oxygen vacancies applied in this study may be applicable to other oxide thermoelectric materials.

Exploring non-noble-metal-based bifunctional oxygen electrocatalysts remains a challenge for renewable clean energy applications, including metal–air batteries and dual functionality regenerative fuel cells. Herein, a facile two-step rheological phase reaction strategy was proposed to synthesize metallic cobalt modified MnO–C nanocrystalline composites (Co/MnO–C) for efficiently catalyzing oxygen reduction reactions (ORR) and oxygen evolution reactions (OER). The resulting optimal catalyst, Co/MnO–C, exhibits comparable electrocatalytic properties and superior methanol tolerance relative to commercial platinum black catalyst towards ORR. Furthermore, the critical role of cobalt content on ORR catalytic activity was investigated. In addition, Co/MnO–C also displays remarkable OER activity with an overpotential of 385 mV. Importantly, the facile two-step rheological phase reaction strategy described in this work could provide new methodologies for the synthesis of transition-metal-based catalysts and also offers prospects in raising the ORR and OER activity for many different electrochemical energy technologies.

The present study compared six commonly used algorithms, namely, alternating trilinear decomposition (ATLD), self-weighted alternating trilinear decomposition (SWATLD), alternating coupled two unequal residual functions (ACTUF), parallel factor analysis (PARAFAC), damped Gauss-Newton (dGN) and algorithm combination methodology (ACM). Their performances with respect to the pre-estimated component number, convergence rate, collinearity, noise, small component and slight non-linearity (chromatographic peak drift) were considered. The results indicate that the difference in the performances of the algorithms arises from differences in the computational mode and the construction of loss functions. Among the six algorithms, ATLD, SWATLD, ACTUF and ACM were insensitive to excessive factors; the ability to overcome severe collinearity was in the order of ACM, ACTUF and dGN > SWATLD > ATLD and PARAFAC; PARAFAC, dGN and ACM showed a stronger ability to resist noise; PARAFAC was the most sensitive to a small component; and ATLD and SWATLD could overcome some effect of slight non-linearity (chromatographic peak drift). Additionally, ATLD was found to be the fastest algorithm, and dGN and ACM had faster convergence rates than PARAFAC. This study is helpful for understanding the essential difference in the performances of algorithms and can provide guidance for choosing suitable algorithms for the analysis of three-way data.

The preparation of ordered metal organic frameworks (MOFs) will be a critical process for MOF-based nanoelectrodes in the future. In this work, we develop a novel approach to fabricating a type of MOF electrode based on flexible amino-functionalized graphene paper modified with 2D oriented assembly of Cu3(btc)2 nanocubes via facile interfacial synthesis and an effective dip-coating method. One interesting finding is that 2D arrays of Cu3(btc)2 nanocubes at oil-water interfaces can be transferred on amino-functionalized graphene paper, leading to a densely packed monolayer of Cu3(btc)2 nanocubes with a uniform size loaded on the paper electrode. The electrode demonstrates a variety of excellent sensing performances toward sweat lactate and glucose and has been applied in a non-enzymatic electrochemical biosensing platform for the first time. The modular nature of this approach to assembling MOF nanocrystals will provide new insight into the design of MOF-based electrodes for a wide range of applications in biosensing instruments, wearable electronics, and lab-on-a-chip devices.

A promising method of synthesizing a lithium-containing room temperature polymeric ionic liquid (PIL) by utilizing the zwitterionic effect to turn a lithium salt into a liquid for single lithium-ion conduction was proposed. In this work, the room temperature PIL was constructed by the equimolar monomer mixture of zwitterion 3-(1-vinyl-3-imidazolic)propanesulfonate (VIPS) and 4-styrenesulfnny(trifluoromethylsulfony)imde (LiSTFSI) based on intermolecular electrostatic interactions. In situ photopolymerization with flexible chain poly(ethylene glycol)methyl ether methacrylate (PEGM) and cross-linker poly(ethylene glycol)dimethacrylate (PEGDM) in the presence of propylene carbonate (PC) generated free-standing PIL electrolyte films. The PIL electrolytes with Li+-rich channels have an excellent lithium transference number approaching unity (0.93 at room temperature) while attaining comparable ionic conductivity (σ ≈ 1.31 × 10-4 S cm-1 at 30 °C). The charge-discharge performance of a Li/LiFePO4 half-cell equipped with this PIL electrolyte would provide a promising model system for novel single lithium ion conductors.

An efficient and facile method to fabricate a surficial dispersive heterojunction based on the assembly of g-C3N4 nanoparticles was proposed. A p-n nano heterojunction composed of BiOI and g-C3N4 was constructed by simply loading g-C3N4 nanoparticles on flower-like BiOI nanosheets. The structure-dependent optical, electronic and photoelectric properties were investigated, and the structure-property relationship was discussed. The results show that the g-C3N4 nanoparticles are uniformly loaded on the surface of BiOI nanosheets and thus form a p-n heterojunction with an intimate interface. The as-prepared samples exhibit enhanced photocatalytic degradation ability towards MO under visible-light irradiation. With the unique structure and morphology, enhanced visible-light photocatalytic activities are achieved owing to the synergistic effect of light harvesting, high transfer efficiency and enhanced separation efficiency of photo-generated carriers.

A new metal–organic framework, [Co(L)]·1.5H2O (1), has been successfully synthesized from an organic ligand, 3-carboxy-1-(4′-carboxybenzyl)-2-oxidopyridinium. Compound 1 displays a novel 3D framework with a capsule-shaped cavity and a hexanuclear [Co6] cluster. The temperature-dependent magnetic susceptibility of compound 1 has been investigated. The electrochemical application of compound 1 as a lithium-ion battery anode material was also explored. To improve the electrochemical performance of compound 1, we utilized compound 1 as a novel precursor to prepare a Co3O4@C composite. By comparison, the Co3O4@C composite shows a higher capacity and better cycling performance, which provides a new direction for the design of anode materials for lithium-ion batteries.

Rational design of SnO2 nanomaterials with superior architectures and excellent electrochemical properties is highly desirable for lithium ion storage. Here, several SnO2 nanoparticles with different exposed crystal planes, such as {101}, {110} and {221} facets, are developed and further embedded into graphene/carbon nanotube (G/CNT) networks, achieving highly conductive carbon/SnO2 films (C/SnO2) with homogeneous dispersion of SnO2 nanoparticles. Three-dimensional (3D) G/CNT networks with highly porous structures and electronic contacts with imbedded SnO2 nanoparticles provide excellent pathways for transfer of electrons and ions and further buffer structural changes of SnO2 nanocrystals during lithium-ion insertion/extraction processes. Close contact between G/CNT matrix and embedded SnO2 nanoparticles ensures that all high-energy {221} facets of SnO2 are exploited during rapid electrochemical reactions. The high electrical conductivity of G/CNT networks can further prevent pulverization of nanostructured SnO2. As a result, C/SnO2 film with 90% content of octahedral SnO2 nanocrystals (C/SnO2-O (90%)) exhibits superior reversible specific capacity of 1008 mA h g-1 at 0.1 A g-1, excellent rate capability, low internal resistance and long-term cycling stability for 1000 cycles. These results further confirm that SnO2 nanocrystals with high-energy {221} facets can provide numerous active sites for lithium ion storage than other SnO2 nanomaterials.

Gabapentin (GAB) is an emerging contaminant that is frequently detected in water bodies across the globe. The present study used zebrafish as a model organism to investigate the effects of GAB on the early development of zebrafish and on its antioxidant system. Acute toxicity tests indicated that the 96 h LC50 value of GAB for zebrafish embryos was 59.9 g L−1. Further, it was observed that GAB causes malformation of embryos such as hemagglutination and pericardial edema. Compared to the control group, a significant enhancement (p < 0.05) of heartbeat rates was found at GAB concentrations exceeding 50 mg L−1, while the swimming frequency was clearly increased upon exposure to GAB at a concentration of 100 mg L−1 (p < 0.05). Additionally, the development of the zebrafish embryo was also negatively impacted after exposure to GAB as demonstrated by significantly decreased body lengths. Exposure to GAB at concentrations exceeding 50 mg L−1 significantly influenced the development of zebrafish, leading to malformation of organs and abnormal movements. Although no significant developmental effects of GAB were observed at environmentally relevant concentrations (0.1 and 10 μg L−1), further research about the antioxidant system confirmed that severe oxidant injury happened inside the organisms. catalase (CAT), lactate dehydrogenase (LDH), glutathione S-transferase (GST), glutathione (GSH) and the ability of inhibition of hydroxyl radicals (IHR) were used as biomarkers in the present study to illustrate GAB toxicity at environmentally relevant concentrations. The results showed that activities of CAT, LDH and GST as well as IHR were all elevated after GAB exposure, which proved that ROS were formed in the body as derived from GAB exposure. Among all of these biomarkers, CAT was the most sensitive one to evaluate the influence of GAB, and showed a significant increase even at a very low exposure concentration (0.1 μg L−1).

Compounds consisting of unsubstituted, monofluoro and difluoro substituted benzothiadiazole bonded to two tetraphenylethenes were successfully prepared by palladium catalyzed Suzuki-Miyaura cross-coupling reaction of their corresponding co-monomers. All compounds exhibited aggregation-induced emission characteristics when the water fraction was higher than 60% in the THF/water mixtures. The emission maximum for the three compounds was blue-shifted when the water content reached 90% compared to that in THF solution. The intensity of emission maximum of difluorinated benzothiadiazole linked with two tetraphenylethenes was 2.5 times higher in 90% water compared to those in THF solution. Surprisingly, two liquid crystal phases with two distinct emission colors were observed only for the compound containing difluorinated benzothiadiazole bonded to two tetraphenylethene. All compounds showed remarkable solvatochromic properties in selected solvents with different polarities. The powder XRD results and mechanochromism of the compounds suggested that the solid state structures can change from one form to another by grinding, fuming or annealing processes.

A Ni-catalyzed direct C-H bond sulfenylation of acylhydrazines was developed. The reaction used N-(pyridinyl)hydrazine as the bidentate-directing group, which can be smoothly removed through reductive N-N cleavage. This system can bear various important functional groups, providing an efficient route for the preparation of diverse diaryl sulfides.

In this study, a novel dual-mode luminescence phosphor KBaLu(MoO4)3:Tb3+,Yb3+ has been synthesized by high-temperature solid-state reactions, and the crystal structures have been determined for the first time. Single-crystal X-ray diffraction data reveal that its space groups are C2/c. The crystalline structure is constituted by K/BaO8 distorted square antiprisms, distorted LuO8 polyhedra and two kinds of distorted MoO4 tetrahedra, which form chains lying along the c-axis. Spectroscopic properties and energy transfer mechanisms are investigated by detailed analyses of emission and excitation spectra and excited-state lifetimes. The KBaLu(MoO4)3:Tb3+,Yb3+ phosphor shows dominant green emissions in the visible region, which are due to 5D4 → 7F5 transition of Tb3+ under excitation light in ultraviolet region as well as a 980 nm laser, and the CIE coordinates are close to the Society of Motion Picture and Television Engineers (SMPTE) standard values for primary green (0.310, 0.595). With the increasing temperature, the luminescence of KBaLu(MoO4)3:Tb3+,Yb3+ phosphor decreases almost linearly with the CIE coordinate variation from (0.326, 0.616) to (0.327, 0.530), which results in photoluminescence color variation from primary green to yellowish-green. The present results demonstrate the successful synthesis of a dual-mode luminescence material KBaLu(MoO4)3:Tb3+,Yb3+ phosphor with both up- and down-conversion luminescence properties; moreover, it can be used as a potential spectrum converter in display lighting and anti-counterfeiting.

4-Bromo substituted [2.2]paracyclophane-1,9-diene was synthesized from the corresponding dithia[3.3]paracyclophane in three steps through benzyne Steven rearrangement, oxidation, and a thermal elimination reaction. 4-Triphenylvinylphenyl substituted [2.2]paracyclophane-1,9-diene was successfully prepared by the Suzuki–Miyaura cross-coupling reaction of 4-bromo substituted [2.2]paracyclophane-1,9-diene and 4,4,5,5-tetramethyl-2-(4-(1,2,2-triphenylvinyl)phenyl)-1,3,2-dioxaborolane using Pd(OAc)2 as a catalyst, S-Phos as a ligand and K3PO4 as a base. The structures of bromo substituted [2.2] paracyclophane-1,9-diene and triphenylvinylphenyl substituted [2.2]paracyclophane-1,9-diene were fully characterized by 1H NMR spectroscopy and X-ray crystallography. 4-Triphenylvinylphenyl substituted [2.2]paracyclophane-1,9-diene exhibited aggregation-induced emission characteristics when the water fraction was higher than 80% in the THF/water mixtures. 4-Triphenylvinylphenyl substituted [2.2]paracyclophane-1,9-diene displays much higher fluorescence when the water fraction is 90% compared to that of model compounds due to both through bond and through space conjugation. To the best for our knowledge, we are the first to synthesize triphenylvinylphenyl substituted [2.2]paracyclophane-1,9-diene with aggregation-induced emission characteristics.

Maleate and fumarate-based unsaturated copolyesters are of interest as biomedical materials with tailorable properties. However, the preparation of unsaturated copolyesters with controllable maleate (cis) and fumarate (trans) isomer compositions is still a great challenge in polymer chemistry, because cis units always unbridledly isomerize to trans units in the polymerization process. Herein, we have presented a universal method for the facile synthesis of stereochemistry-controllable poly(butylene maleate-co-butylene fumarate) (P(BM-co-BF)) copolyesters. Then, we prepared a series of comparably high-molecular weight (Mw > 30 kDa) biobased copolyesters with a wide range of well-controlled cis–trans compositions. The solid-state microstructure, morphology, and crystallization behavior of P(BM-co-BF) copolyesters were systematically investigated to explore the respective effects of cis and trans isomers on the physical properties of copolymers. With the increment of the cis content, the copolyesters transform the phase state from semicrystalline to completely amorphous with tunable thermal and mechanical properties, which can be attributed to the conformational geometry effect. Consequently, the variation of the stereochemistry composition allows the physical properties to be tailored over a broad range. Furthermore, a merit of these copolyesters is to provide a chemoselective polymer platform for the introduction of various functional groups onto the backbone through a green aza-Michael addition reaction under extremely mild conditions, such as PEG, hydroxyl, alkynyl, etc. These incorporated functional groups can be used for the selective tailoring of the polyesters, which dramatically increase their potential for a wide variety of applications.

The complexation of primary alkyl halides Cn–X (n = 5, 6 and 9; X = Cl, Br and I) in a new, water-soluble cavitand is evaluated. The complexes are dynamic; the host and guest adapt their shapes to accommodate each other and the guest undergoes tumbling or yo–yo like motions in the space. Evidence for halogen bonding of the halides to the aryl surfaces of the cavitand is presented.