Search

SnO2 films as a promising electron transport layer (ETL) have been widely used in planar-type perovskite solar cells to achieve an impressive improvement in the conversion efficiency. However, compared with a mesoporous ETL, the interfacial charge carrier transfer of the SnO2 ETL is severely limited due to the issues of oxygen vacancy defects and crystal lattice mismatch between SnO2 and the perovskite, which generally leads to the growth of randomly stacked and porous perovskite layers and subsequently impacts the charge transport and transfer properties. In this work, we developed a facile approach by inducing a bifunctional molecule, β-alanine, into the SnO2 ETL, which can serve as a bridge to modulate the interfacial charge transfer and the perovskite crystallization kinetics. Benefited by the interfacial β-alanine, we grew a highly orientational perovskite layer that exhibited superior charge transport properties. Meanwhile, the β-alanine caused an intimate connection between the perovskite and SnO2 to enhance the interfacial charge transfer. As a result, the power conversion efficiency (PCE) of the β-alanine-modified device achieved a much-improved value of 19.67% and showed high reproducibility. This work provides a way for developing a high-performance ETL toward the scalable fabrication of highly efficient PSCs.

Hyperectumine (1), the first C19 benzylisoquinoline alkaloid with a complicated ring system, was isolated from Hypecoum erectum and structurally characterized. Its biosynthetic origin should involve a hybrid pattern of C8 + C8 + C1 + C2, from which a C17 benzylisoquinoline alkaloid might be further attacked by a malonamic acid and undergo decarboxylation and cyclization to produce 1. Compound (-)-1 exhibited moderate anti-inflammatory activity via suppression of LPS-activated inflammatory mediators in RAW 264.7 macrophage cells.

Chlorin e6 (Ce6) is a promising photosensitizer for tumor photodynamic therapy (PDT). However, the efficacy of Ce6 PDT is limited by Ce6's poor water solubility, rapid blood clearance, and inadequate accumulation in the tumor tissue. This problem is tackled in this work, wherein functionalized superparamagnetic iron oxide nanoparticles (IO-NPs) were used as carriers to deliver Ce6 to melanoma. The IO-NPs were coated with polyglycerol (PG) to afford good aqueous solubility. The chemotherapeutic agent doxorubicin (DOX) was attached to the PG coating via the hydrazone bond to afford affinity to the cell membrane and thereby promote the cell uptake. The hydrophobic nature of DOX also induced the aggregation of IO-NPs to form nanoclusters. Ce6 was then loaded onto the IO nanoclusters through physical adsorption and coordination with surface iron atoms, yielding the final composites IO-PG-DOX-Ce6. In vitro experiments showed that IO-PG-DOX-Ce6 markedly increased Ce6 uptake in mouse melanoma cells, leading to much-enhanced photocytotoxicity characterized by intensified reactive oxygen species production, loss of viability, DNA damage, and stimulation of tumor cell immunogenicity. In vivo experiments corroborated the in vitro findings and demonstrated prolonged blood clearance of IO-PG-DOX-Ce6. Importantly, IO-PG-DOX-Ce6 markedly increased the Ce6 distribution and retention in mouse subcutaneous melanoma grafts and significantly improved the efficacy of Ce6-mediated PDT. No apparent vital organ damage was observed at the same time. In conclusion, the IO-PG-DOX NPs provide a simple and safe delivery platform for efficient tumor enrichment of Ce6, thereby enhancing antimelanoma PDT.

Bronsted acid-catalyzed direct C(sp2)-H alkylation of N-heteroaromatics with cyclic ethers via a cross-dehydrogenative coupling reaction in the presence of benzoyl peroxide was developed. This methodology successfully provided an easy access to a variety of alkyl-substituted quinoxaline, benzoimidazole, pyrazine, pyrimidine, quinoline, isoquinoline, and pyridine derivatives in up to 94% yield under metal-free conditions.

Yttrium borides have attracted much attention for their superconducting and high chemical stability. However, the fundamental knowledge of the mechanical properties and hardness of yttrium borides is rather lack. Here, we performed a systematic investigation on yttrium borides with various stoichiometries based on an unbiased CALYPSO structure search method and first-principles calculations. A new YB6 compound with R3m hexagonal structure is observed, which is more stable than the experimental synthesized Pm3m phase. The calculated formation enthalpy, elastic constants, and phonon dispersions distinctly show that the R3m-YB6 is energetically, mechanically, and dynamically stable. The density of states and electronic band structure reveal that all the stable yttrium borides are metallic. Based on a semiempirical method, the Vicker hardness of R3m-YB6 is expectant to be 37.0 GPa, indicating it is a potential ultrahard metal. Our results provide insights for future synthesis and design of new type functional materials.

Chaenomeles speciosa (Sweet) Nakai is a dual-purpose Chinese herbal medicine and functional food favored by minorities in Southwest China, and its fruits are used for the treatment of dyspepsia, dysentery, enteritis, and rheumatism inflammation. Some diseases may be related to microbial infection; however, it is not known how the fruits possess antimicrobial activity. We evaluated the antimicrobial bioctivity of different evaluation extracts of C. speciosa fruits by in vitro and in vivo with colony-forming unit assays, and the strongest bioactive-guided fraction was selected for column chromatography (CC), UHPLC-QTOF-MS/MS, and NMR spectroscopy to confirm the chemical constituents. The most possible antimicrobial mechanism of C. speciosa fruits was explored by metabolomics approach, fluorescence microscopy imaging, and scanning electron microscopy (SEM). Thirty compounds, which were major characteristic ions of the bioactive fraction, were determined precisely. The bioactive fraction could inhibit 18 pathogenic microorganisms, significantly reduced, especially drug-resistant bacteria, compared to ampicillin sodium salt, fluconazole, and berberine chloride form; and the minimum inhibitory concentration (MIC) or minimum fungicidal concentration (MFC) values were in the range of 0.1-1 mg/mL. The compounds 2'-methoxyaucuparin (1) and oleanolic acid (20) not only have antibacterial activity but also may have synergistic effects. Further, the bioactive fraction might inhibit the biofilm formation, enhance immunity, and restore bacterial infection damage in vitro and in vivo to kill microorganisms. The data indicated that C. speciosa fruits' major bioactive fraction enriched with triterpenes, flavonoids, and phenolics could be developed as a functional supplement for individuals to prevent and treat microbial infection.

The amino dicarbonylation of aryl halides affording α-ketoamides with Pd catalysts is highly dependent on the stereoelectronic properties of the involved ligands. Ionic diphosphine ligand L4 can se...

Hydrogel-based wearable devices have attracted tremendous interest due to their potential applications in electronic skins, soft robotics, and sensors. However, it is still a challenge for hydrogel-based wearable devices to be integrated with high conductivity, a self-healing ability, remoldability, self-adhesiveness, good mechanical strength and high stretchability, good biocompatibility, and stimulus-responsiveness. Herein, multifunctional conductive composite hydrogels were fabricated by a simple one-pot method based on poly(vinyl alcohol) (PVA), sodium alginate (SA), and tannic acid (TA) using borax as a cross-linker. The composite hydrogel network was built by borate ester bonds and hydrogen bonds. The obtained hydrogel exhibited pH- and sugar-responsiveness, high stretchability (780% strain), and fast self-healing performance with healing efficiency (HE) as high as 93.56% without any external stimulus. Additionally, the hydrogel displayed considerable conductive behavior and stable changes of resistance with high sensitivity (gauge factor (GF) = 15.98 at a strain of 780%). The hydrogel was further applied as a strain sensor for monitoring large and tiny human motions with durable stability. Significantly, the healed hydrogel also showed good sensing behavior. This work broadens the avenue for the design and preparation of biocompatible polymer-based hydrogels to promote the application of hydrogel sensors with comfortable wearing feel and high sensitivity.

The design and synthesis of low-cost and efficient bifunctional electrocatalysts for water splitting are critical and challenging. Hereby, a bimetallic phosphide embedded in a N and P co-doped porous carbon (FeCoP2@NPPC) material was synthesized by using sustainable biomass-derived N- and P-containing carbohydrates and non-noble metal salts as precursors. The obtained material exhibits good catalytic activities in hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting. The bimetallic alloy phosphide (FeCoP2) is the active site for electrocatalysis. Theoretical calculation indicates that the sub-layer Fe atoms and top-layer Co atoms in FeCoP2 exhibit a synergistic effect for enhanced electrocatalytic performance. The carbon matrix around the FeCoP2 can prevent the corrosion during the catalytic reactions. The hierarchically porous structure of the FeCoP2@NPPC material can promote the transfer of electrons and electrolyte, and increase the contact area of the active sites and electrolytes. N- and P-containing functionalities improve the wetting and conductivity properties of the porous carbon. Due to the synergistic effects, FeCoP2@NPPC requires a low overpotential of 114 and 150 mV at the current density of 10 mA cm-2 for HER in 0.5 M H2SO4 and 1.0 M KOH, and an overpotential of 236 mV for OER in 1.0 M KOH solution, which are much lower than those of FeP@NPPC and CoP@NPPC. Based on the density functional theory calculation, FeCoP2 yields the smallest Gibbs free energy change of rate-determining step among the samples, which leads to better electrochemical performances. In addition, when FeCoP2@NPPC was used as a bifunctional catalyst in water splitting, the electrolyzer needed a low voltage of 1.60 V to deliver the current density of 10 mA cm-2. Furthermore, this work provides a strategy for preparing sustainable, stable, and highly active electrocatalysts for water splitting.

A systematic theoretical study of the regulating effect of the substituent position on the photoinduced deactivation process of the benzyluracil systems has been performed based on the high-level static electronic structure calculations and on-the-fly full-dimensional excited-state dynamics simulations. Similarities and differences coexist for the two systems by comparative studies on the photoinduced deactivation process of the 5-benzyluracil (5-BU) and 6-benzyluracil (6-BU) systems. They both obey an S2 → S1 → S0 two-step decay pattern, and the decay coordinates of the S2 → S1 and S1 → S0 processes are mainly driven by the elongation of the bridging bond and the out-of-plane ring deformation motion, respectively. However, the puckering motion occurring at the C2 atom in the uracil fragment dominates the decay pathway of the 5-BU system. On the contrary, the puckering motion at the C5 atom in the benzene fragment mainly drives the decay coordinate of the 6-BU system. Therefore, the substituent position could play significant roles in the deactivation process of the benzyluracil systems. Moreover, the S1 → S0 decay process of the 6-BU system consists of five pathways, possessing a more complex deactivation picture than the 5-BU system. The fitted time scale of the puckering motion is compatible with the experimentally observed lifetimes. This work provides a fundamental understanding of the photophysical and photochemical properties of the benzyluracil systems and can give rational suggestions to further design or regulate the bionic molecular systems.

Health and wellbeing are significantly impaired by alcoholic liver disease (ALD), and although some lactic acid bacteria strains have been shown previously to relieve ALD symptoms, the mechanisms behind these effects are still unclear. Here, the Lieber-DeCarli liquid diet containing alcohol was fed to C57BL/6J mice for 6 weeks to build a chronic alcoholic liver lesion model to study the protective effects and possible mechanisms of Lactobacillus mixture (Lactobacillus plantarum KLDS1.0344 and Lactobacillus acidophilus KLDS1.0901). The results showed that Lactobacillus mixture improved intestinal epithelial permeability and reduced the serum lipopolysaccharide (LPS) levels. Furthermore, Lactobacillus mixture inhibited liver lipid accumulation, oxidative stress, and inflammation by regulating AMPK, Nrf-2, and TLR4/NF-κB pathways. Importantly, the Lactobacillus mixture modulated the gut microbiota, resulting in increased short-chain fatty acid (SCFA) producers and decreased Gram-negative bacteria. Taken together, these findings indicated that the Lactobacillus mixture could positively regulate the gut microbiota, causing increased levels of SCFAs, which inhibited alcohol-induced liver lipid accumulation and oxidative stress through the gut-liver axis. Moreover, following administration of the Lactobacillus mixture, the improvement of intestinal epithelial permeability and the reduction of Gram-negative bacteria led to the decrease of LPS entering the portal vein, thereby inhibiting alcohol-induced liver inflammation.

Epoxidized soybean oil (ESO)-derived epoxy thermosets are usually limited by their poor mechanical properties and non-reprocessability. Herein, we report sustainable epoxy vitrimers synthesized fac...

Clerodendranthus spicatus, popularly known as "kidney tea" in China, is consumed traditionally as a functional food for treatment of renal inflammation, dysuria, and gout. We evaluated the effects of C. spicatus on gout by assessing activities of antihyperuricemia, anti-gouty arthritis, and analgesia in vivo, and the results indicated that the ethyl acetate fraction shows potential activities. Subsequent phytochemical investigation of this fraction led to the isolation of 32 compounds, consisting of 20 diterpenoids (including the new orthosiphonones E and F), 2 triterpenoids, 6 flavonoids, 2 lignanoids, and 2 phenolic acid derivatives. Pharmacological investigation of the pure compounds in the cellular model of hyperuricemia indicated that 12 compounds could promote the excretion of uric acid at 10 μg/mL, and compounds 3, 4, 5, and 21 had better effects than that of benzbromarone, a famous uricosuric drug. Furthermore, compounds 4, 6, 7, 9, 14, 15, 23, 26, and 31 showed significant anti-gouty arthritis activity in monosodium urate (MSU)-induced joint swelling at the dose of 50 mg/kg, while compounds 4, 5, 7, 9, and 26 exhibited significant inhibition of pain induced by acetic acid. Our findings provided scientific justification to support the traditional application of "kidney tea" for treating gout and suggested its good application prospects in the future.

The design of highly efficient catalysts for the cleavage of various lignin linkages is the key step in the depolymerization of lignin. In this paper, strong-base-modified covalent triazine framewo...

The fruits of Lycium barbarum have a long history as an edible and medicinal food in Asian regions and have multiple consumption methods; the polysaccharides (LBPs) are commonly considered as their major immunological constituents. The current study revealed that the total phenolic amide moieties from L. barbarum fruits showed greater potential immunomodulatory activity in vivo than did LBPs. Through subsequent investigation on the immunological bioactive phenolic amides, three new phenolic amides, lyciumamides L-N (1-3), as well as 12 analogues, were obtained from the total phenolic amide fraction. Extensive spectroscopic methods were used to elucidate the new structures. Compounds 4-6 and 15 significantly promoted LPS-stimulated B splenocyte, while compounds 4-6 displayed accelerative effects on the proliferation of Con A-stimulated T lymphocytes at a concentration of 20.0 μg/mL. These data indicated that extracts from L. barbarum fruits enriched with phenolic amides could be developed as a nutritional dietary supplement for immunocompromised individuals.

Dactylicapnosines A (1) and B (2), two reconstructed aporphines with unprecedent five-membered carbon ring D, were isolated from Dactylicapnos scandens, in which dactylicapnosine A showed potent anti-inflammatory bioactivity in vitro. Inspired by its biosynthetic pathway, the total synthesis of dactylicapnosine A via 10 steps has been achieved and afforded enough material to prove its significant anti-inflammatory effect in vivo.

Cytosolic sulfotransferases (SULTs) acting as phase II metabolic enzymes can be used in the sulfonation of small molecules by transferring a sulfonate group from the unique co-factor 3′-phosphoadenosine 5′-phosphosulfate (PAPS) to the substrates. In the present study, molecular dynamics (MD) simulations and ensemble docking study were employed to theoretically characterize the mechanism for the effect of co-factor (PAP) and ligands (LCA, raloxifene, α-hydroxytamoxifen, ouabain, and 3′-phosphoadenylyl sulfate) on structural stability and selectivity of SULT2A1 from the perspective of the dynamic behavior of SULT2A1 structures. Structural stability and network analyses indicated that the cooperation between PAP and LCA may enhance the thermal stability and compact communication in enzymes. During the MD simulations, the obviously rigid region and inward displacement were detected in the active-site cap (loop16) of the conformation containing PAP, which may be responsible for the significant changes in substrate accessibility and catalytic activity. The smaller substrates such as LCA could bind stably to the active pocket in the presence of PAP. However, the substrates or inhibitors with a large spatial structure needed to bind to the open conformation (without PAP) prior to PAPS binding.

Exosomes are membrane-enclosed phospholipid extracellular vesicles. In spite of their great promise as noninvasive biomarkers for cancer diagnosis, sensitive detection of exosomes is still challenging. Herein, the detection of exosomes was changed to the detection of DNA after recognition of exosomes with its aptamers. CD63 aptamer and EpCAM aptamer were used for the detection of MCF-7 cell-secreted exosome. The recognition process was amplified through the movements of a three-dimensional DNA walker. And then, Exonuclease III- assisted electrochemical ratiometric sensor was applied for further signal amplification. Under optimal conditions, the detection limit of 1.3 × 104 particles/mL was obtained with excellent selectivity. Furthermore, clinical application test for the detection of exosomes in human serum was also verified.

We reported herein an unexpected cinchona alkaloid-derived squaramide-catalyzed asymmetric two-component Ugi-type reaction of α-aryl-substituted isocyanoacetates with C,N-cyclic azomethine imines, ...

The solubility parameters of four ionic liquids (ILs), 1-ethyl-3-methylimidazolium methyl sulfate ([EMIM][MeSO4]), 1-butyl-3-methylimidazolium methyl sulfate ([BMIM][MeSO4]), 1-hexyl-3-methylimidaz...

Two new Tricholoma terpenoids, tricholopardins A and B, were isolated from the fruiting bodies of the basidiomycetes Tricholoma pardinum. Their structures were elucidated by spectroscopic methods, as well as electronic circular dichroism and optical rotatory dispersion calculations. Tricholopardin A potently inhibited nitric oxide production in lipopolysaccharide-induced RAW264.7 macrophages with an IC50 of 0.08 μM. Its anti-inflammatory effects on three inflammatory mediators were also evaluated. A plausible biosynthetic pathway for these products is discussed.

On the basis of the bifunctional 1,4-bis(imidazol-1-yl)terephthalic acid (H2BTA), four three-dimensional (3D) Pb(II)/Zn(II) coordination polymers (CPs), {[Zn(BTA)]·1.5(DOA)}n (1), [Zn(BTA)]n (2), [Pb(BTA)]n (3), and [Pb(BTA)]n (4), have been synthesized (DOA = dioxane). Structural analyses reveal that two Zn(II)-based complexes are 3D (4,4)-c pts pseudo-supramolecular isomers for 1 and 2, and two Pb(II)-based complexes are supramolecular isomers with a 3D (4,5,6)-c net for 3 and a 3D 6-c pcu net for 4, respectively. Furthermore, the gas adsorption behaviors of complexes 1 and 2 for N2, CO2, and CH4 have been studied in detail at varying temperatures, and the results showed that the adsorption capacities to CO2 at 273 K and 1 bar are stronger than those of other gases. Meanwhile, the selectivity of 1 and 2 for CO2/CH4 was evaluated by the usage of the ideal adsorbed solution theory, whose selectivity exceeded those of reported MOFs under similar conditions. In addition, the fluorescent measurements showed ...

Fortifying food and beverage products with combinations of bioactive agents is a major initiative within the food industry because of their potentially additive or even synergistic benefits for human health. Coix seed oil (CSO) has been reported to possess anticancer activity, whereas β-carotene (βC) is a natural antioxidant that may also exhibit anticancer activity. However, both of these bioactives are insoluble in water and have poor oral bioavailability. The aim of this study was to overcome these obstacles by encapsulating both βC and CSO into liposomes (L-βC-CSO). The effect of different combinations of these two bioactive agents on the physiochemical properties, stability, release, antioxidant activity, and anticancer activity of the liposomes was then determined. Increasing the CSO level decreased the βC entrapment efficiency, increased the particle size, reduced the polydispersity, and raised the magnitude of the surface potential of the bioactive-loaded liposomes. Moreover, the βC and CSO levels affected their orientation within the lipid bilayer, which also influences the physiochemical properties, stability, and in vitro release behavior of the system. Compared to liposomes containing single bioactive types, the combined systems exhibited higher bioavailability and increased anticancer and antioxidant activity. These results suggest that the combined bioactive-loaded liposomes could be an efficient formulation for potential applications in functional foods and supplements.

In this study, the photoinduced ultrafast deactivations of O6-methylguanosine in aqueous solution are mapped by employing multireference methods with implicit solvation model on a reduced model compound 9-methyl-O6-methylguanine (9Me-6MeGua). Although four S1/S0 minimal energy conical intersections (MECIs) are located, energy profiles indicated that only two of them are involved in excited-state decay processes and account for the C2 and C6 reaction coordinates, respectively. To reach both the involved MECIs, 9Me-6MeGua needs to surmount an energy barrier. The computed energy barrier of the C6 reaction coordinate is extremely low and should be responsible for the experimentally observed fast internal conversion (IC) process (∼0.95 ps), whereas the C2 reaction coordinate accounts for the slow IC process (∼41 ps). Eventually, we deliver a detailed mechanism for ultrafast deactivations of 6MeGuo, which explains well the recent experimental results [Ashwood, B.; J. Phys. Chem. Lett. 2017, 8, 4380−4385] and re...

Carbon nanotubes supported palladium (Pd/CNTs) catalyst displayed excellent activity toward hydrogenation of polystyrene (PS) to produce polycyclohexylethylene (PCHE) with added commercial values. However, its application is limited by the costly catalyst filtration process and energy-consuming elevated agitation speed. Herein, a dense, homogeneous and strongly attached layer of CNTs was decorated on nickel foams and employed as the catalyst support for palladium nanoparticles. Structured catalyst (Pd/CNTs@NF) was directly used as the catalyst stirrer in a rotating foam stirrer reactor (RFSR) for PS hydrogenation. Owing to the enhanced mass-transfer process, the hydrogenation degree reached 68.8%, which was 45.1% higher than that obtained in a slurry reactor using powdered Pd/CNTs catalyst under identical reaction conditions. Outstanding attachment strength of CNTs on the foam and catalytic stability in eight runs of recycling were also demonstrated. This work elucidates the promising feasibility of struc...

Both connate water and the injected water through hydraulic fracturing can coexist with methane inside shale nanopores where two-phase flow possibly occurs. Few studies have been pertaining to two-...

The microstructured and hyperdoped silicon as a superior photoelectric and photovoltaic material is first studied as a gas-sensing material. The material is prepared by femtosecond-laser irradiation on selenium-coated silicon and then fabricated as a conductive gas sensor, targeting ammonia. At room temperature, the sensitivity, response time, repeatability, distinguishability, selectivity, and natural aging effect of the sensor have been systematically studied. Results show that such black silicon has good potential for application as an ammonia-sensing material. On the basis of its unique optoelectronic properties, an additional optical drive is proposed for the formation of an optical and electric dual-driven sensor, which is achieved by asymmetric light illumination between the two electrode regions. In a certain range of applied voltage, the sensitivity is enhanced dramatically and even tends to be infinite. For the aged device with degraded sensitivity, a two-order increment is obtained for 500 ppm of NH

Acetyl hexapeptide-3, a competitive SNAP-25 inhibitor that mimics the action of botulinum neurotoxins but is nontoxic, was successively synthesized in a solution by peptide chemistry with a “3+2+1” fragment coupling strategy. The difficulties encountered in the convergent route, an optimization on scalable process, and controls on potential epimerization are systematically discussed. Final purification led to the target product’s overall 36.5% yield with 98.3% purity and excellent optical purity.

A base-promoted cascade reaction for the regiospecific synthesis of substituted 3-hydroxyisoindolinones under transition-metal-free conditions is developed. The base-mediated C–C bond coupling and N-α-sp3C–H bond hydroxylation are involved in this procedure, which features high regioselectivity, efficiency, and environmental friendliness. Various substituted 3-hydroxyisoindolinones, including some bioactive molecules, were provided in up to 93% yield for 28 examples.

Core–shell structured nitrogen-doped porous carbon@silica material with uniform structure and morphology was synthesized via a sol–gel method. During this process, a commercial triblock copolymer and the in situ formed pyrrole-formaldehyde polymer acted as cotemplates, while tetraethyl orthosilicate acted as silica precursor. The synergetic effect of the triblock copolymer and the pyrrole-formaldehyde polymer enables the formation of the core–shell structure. Herein, the pyrrole-formaldehyde polymer acted as not only the template, but also the nitrogen-doped carbon precursor of the core. The obtained core–shell structured porous material possesses moderate Brunauer–Emmett–Teller specific surface area (410 m2 g–1) and pore volume (0.53 cm3 g–1). Moreover, corresponding hollow silica spheres or nitrogen-doped porous carbon spheres can be synthesized by calcining the core–shell structured material in air or etching it with HF. The X-ray photoelectron spectroscopy results reveal that the nitrogen states of th...

The structure and proton tautomerism of imidazole-doped cellulose (Cell-Im), an excellent solid state proton conductor, has been studied by 15N solid-state NMR techniques. 1H–15N HETCOR NMR experiments allowed us to assign the water and cellulose–OH resonances and to establish 1H–15N connectivities. 15N CPMAS NMR experiments showed that imidazole is immobile and its tautomerism quenched below 263 K, whereas at higher temperatures, a broad distribution of slow and fast exchanging protons is observed, where the fraction of the latter increases with temperature. The tautomerism is found to be coupled to proton exchange with water molecules. From an analysis of the temperature-dependent fractions of both phases, a broad distribution of energies of activation of the tautomerization of Cell-Im is obtained, exhibiting a maximum at 42 kJ mol–1 and a width of 8.2 kJ mol–1. The tautomerization is slower than in the case of imidazole dissolved in wet organic solvents. These results indicate that imidazole is located...

A shape-persistent cryptand 1, containing two face-to-face oriented electron-deficient 2,4,6-triphenyl-1,3,5-triazine units separated by approximately 7 Å, and bridged by two rigid 1,8-naphthyridine linkers and a pentaethylene oxide loop, is created for capturing polycyclic aromatic hydrocarbons. Cryptand 1 formed 1:1 complexes with PAH guest molecules, such as phenanthrene (6), anthracene (7), pyrene (8), triphenylene (9), and tetraphene (10). The single-crystal structure of complex 6⊂1 revealed that 6 was included in the cavity of 1 via face-to-face π···π stacking interactions. Soaking crystalline 1 in a toluene solution of anthracene resulted in anthracene from the toluene solution being picked up by the crystalline solid of 1.

We report on the realization of polymer light-emitting diodes (PLEDs) based on fluorescent polythiophene (PT)-based insulated molecular wires (IMWs). PLEDs using PT emitting layers traditionally have low external quantum efficiencies (ηeqe) below 0.1%. Moreover, IMWs lack a thorough exploitation for electroluminescent applications due to concerns about reduced charge transport between their chains. We constructed multilayer PLEDs containing PT IMW emitting layers that show the maximum ηeqe close to 1.4%, luminance at 3700 cd/m2, and low turn on voltage at 2.5 V. We also show a strong influence of the thickness of electron transport layer on ηeqe through device optimization and optical simulations.

(R)-(−)-Mandelic acid is an important chiral building block that is widely used in pharmacy and the production of fine chemicals. A more advanced method for obtaining (R)-(−)-mandelic acid is direct hydrolysis of the corresponding racemic mandelonitrile. In order to develop a cost-effective process, a highly efficient enantioselective nitrilase BCJ2315 from Burkholderia cenocepacia J2315 was used for the biotransformation of mandelonitrile to (R)-(−)-mandelic acid. The recombinant Escherichia coli M15/BCJ2315 showed high substrate tolerance and could completely hydrolyze up to 250 mM of mandelonitrile. A fed-batch reaction was performed by periodically or continuously dosing the substrate into the reactor to alleviate substrate inhibition in a monophasic buffer system. Finally, the highest substrate loading (2.9 M) was achieved in the continuous fed batch reaction mode, giving (R)-(−)-mandelic acid at the highest concentration (2.3 M, 350 g/L) with 97.4% ee ever reported. The hydrolysis process was easily...

Polyurethane hybrid membranes containing graphene oxide (GO) with different morphologies were prepared by in situ polymerization. The separation of CO2/N2 gas mixtures was studied using these novel membranes. The results from the morphology characterization of GO samples indicated that the oxidation process in the improved Hummers method introduced oxygenated functional groups into graphite, making graphite powder exfoliate into GO nanosheets. The surface defects on the GO sheets increased when oxidation increased due to the introduction of more oxygenated functional groups. Both the increase in oxygenated functional groups on the GO surface and the decrease in the number of GO layers leads to a better distribution of GO in the polymer matrix, increasing thermal stability and gas separation performance of membranes. The addition of excess oxidant destroyed the structure of GO sheets and forms structural defects, which depressed the separation performance of membranes. The hybrid membranes containing well-distributed GO showed higher permeability and permeability selectivity for the CO2. The formation of GO aggregates in the hybrid membranes depressed the membrane performance at a high content of GO.

A novel series of donor-acceptor star-shaped conjugated macroelectrolytes (CMEs), denoted as 4FTs, including anionic carboxylic acid sodium groups (4FNaT), neutral diethanolamine groups (4FNOHT), and cationic ammonium groups (4FNBrT), were designed, synthesized, and explored as an excellent platform to investigate the impact of various polar pendent groups on self-assembly behaviors. The resulting CMEs with donor-acceptor star-shaped architectures exhibited distinct light-harvesting properties. The interactions between 4FTs and TrNBr, a star-shaped monodisperse CME grafted with cationic quaternary ammonium side chains, were investigated in H2O and CH3OH using steady-state, time-resolved fluorescence, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Highly favored energy transfer has been proven by the excellent spectral overlap between TrNBr fluorescence and 4FTs absorptions which can be tuned by adjusting the pendent polar groups and solvents. It is suggested that self-assembled structures are formed between TrNBr and 4FNaT, while there is no obvious change for TrNBr/4FNOHT and TrNBr/4FNBrT in both H2O and CH3OH at low concentrations (10(-6) M). This result is confirmed by the change of the TrNBr and 4FTs fluorescence properties and the time-resolved fluorescence data. The overall results manifest that at low concentrations the self-assembly between TrNBr and 4FTs is dominated by the electrostatic interactions. This study suggests that the functionalization of pendent polar groups of star-shaped CMEs has proven to be effective to modulate the self-assembly behaviors in dilute solutions and thus provide a strategy to further manage the optoelectronic properties.

Thiadiazolo[3,4-c]pyridine (PT), an important analog of benzothiadiazole (BT), has most recently been explored as a novel electron acceptor. It exhibits more electron-accepting ability and other unique properties and potential advantages over BT, thus inspiring us to investigate PT-based donor-acceptor-type (D-A) conjugated polymer in electrochromics. Herein, PT was employed for the rational design of novel donor-acceptor-type systems to yield a neutral green electrochromic polymer poly(4,7-di(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-[1,2,5] thiadiazolo[3,4-c]pyridine) (PEPTE). PEPTE revealed a lower bandgap (Eg,ele=0.85 eV, Eg,opt=1.12 eV) than its BT analog and also favorable redox activity and stability. Furthermore, electrochromic kinetic studies demonstrated that PEPTE displayed higher coloration efficiency than BT analog, good optical memory, and very fast switching time (0.3 s at all three wavelengths), indicating that PT would probably be a promising choice for developing novel neutral green electrochromic polymers by matching with various donor units.

The feasibility of recovering bioactive substances without surface activity from their aqueous solutions was studied using biosurfactants as collectors. For recovering the isoflavones from the soy ...

A novel trispyrazine-pillared prismatic bicycooxacalixaromatic ligand L is synthesized, and its application in metal-mediated self-assembly is described. Under self-assembly conditions, single chain, double-stranded cross-linked coordination polymer and two-dimensional (2D) coordination polymeric networks were formed via M-L (Ag(+), Cu(2+), and Zn(2+)) coordinative interactions. Structural analyses revealed that the antiparallelly arranged one-dimensional coordination polymers (Cu(2+) and Zn(2+)) are arranged to generate well-defined voids to host aromatic guests (benzene) via C-H···π and π···π interactions, while the double-stranded cross-linked coordination polymer (Ag(+)) contains a rhomboidal [Ag2(L(3))2] (L(3): tridentate ligand) cage motif to include a benzene guest; the "thicker" (thickness: ac 5 Å) 2D coordination polymeric networks (Ag(+), Cu(2+), and Zn(2+)), however, are all formed by connection of one or two kinds of topologically different metallomacrocyclic cage units. These unique metallomacrocyclic cage units in the 2D coordination polymeric networks are capable of hosting different guest species. For instance, the rhomboidal [M2(L(3))2] (M = Ag(+), Cu(2+)) cage units were found to host a benzene or a nitrate anion; a hexahedral [M3(L(3))3] (M = Ag(+)) cage was found to host a ligand L or a DMF molecule; the hexahedral [M4(L(3))4] (M = Cu(2+)) cage was found to host four solvent molecules of benzene; and the rectangular [M3(L(3))3] (M = Cu(2+), Zn(2+)) cage units, however, were found to host two THF molecules. The results highlight the potential of ligand L for applications in the construction of "thicker" 2D coordination polymeric networks with well-defined metallomacrocyclic cage units capable of hosting various guest species.

The stable ionic Rh(I,II,III) complexes [RhI(acac)(CO)(L)]PF6 (2), [RhII2(OAc)4(L)2]2PF6 (3), and [RhIIICl4(L)2]PF6 (4) were synthesized through the complexation of RhI(acac)(CO)2, RhII2(OAc)4(H2O)2, and RhIIICl3·3H2O with the phosphine-functionalized ionic liquid (FIL) 1 ([L]PF6, L = 1-butyl-2-diphenylphosphino-3-methylimidazolium), respectively. The cation of L in 1 is an imidazolium-substituted phosphine with a positive charge vicinal to the P(III) atom, which acts as an electron-deficient donor with π-acceptor character to afford the stable complexes 2–4 due to the presence of retrodonating π-binding between Rh–P linkage. Due to the weakened reducing ability of L, the redox reaction between L and RhCl3·3H2O during the complexation is avoided, leading to the formation of 4, in which the Rh center is in the +3 valence state. Single-crystal X-ray analyses show that 2–4 are all composed of a Rh-centered cation and a PF6– counteranion. The cation of 2 possesses structural similarity to RhI(acac)(CO)(PPh3),...

In this work, the extrusion process of Cu/SiO2 catalysts prepared by the ammonia-evaporation (AE) method has been investigated and optimized in order to obtain materials with convenient catalytic and mechanical properties for their application in the gas-phase hydrogenation reaction of dimethyl oxalate (DMO) to ethylene glycol (EG). Thereby, a variety of Cu/SiO2 extrudates were prepared with different Cu loading. It has been observed that a special microstructure including defects, flaws, and discontinuities plays a significant role on the mechanical strength. Larger CuO grains may act as fracture origins, which negatively affect the mechanical strength. The 20Cu/SiO2 extrudate with high Cu dispersion and high porosity is optimized for hydrogenation of DMO to EG, achieving a 98% conversion of DMO and 85% selectivity of EG under the liquid hourly space velocity (LHSV) of 1.0 h–1.

This paper describes an emerging synthetic route for the production of ethanol (with a yield of ~83%) via syngas using Cu/SiO(2) catalysts. The remarkable stability and efficiency of the catalysts are ascribed to the unique lamellar structure and the cooperative effect between surface Cu(0) and Cu(+) obtained by an ammonia evaporation hydrothermal method. Characterization results indicated that the Cu(0) and Cu(+) were formed during the reduction process, originating from well-dispersed CuO and copper phyllosilicate, respectively. A correlation between the catalytic activity and the Cu(0) and Cu(+) site densities suggested that Cu(0) could be the sole active site and primarily responsible for the activity of the catalyst. Moreover, we have shown that the selectivity for ethanol or ethylene glycol can be tuned simply by regulating the reaction temperature.

A new family of platinum acetylide derivatives containing iptycene building blocks end-capped with 3,4,5-tris(alkoxy)phenyl substituents has been successfully synthesized. The structure of the newly designed complexes was characterized by multinuclear NMR (1H, 31P, and 13C) and mass spectroscopy and elemental analysis. Unexpectedly, all compounds presented good gel formation properties in some common organic solvents. The morphology of the xerogels was investigated by scanning electron microscopy (SEM). An investigation using electronic absorption and emission spectra was carried out to study the spectroscopic properties of all organometallic complexes in both solution and gel states.

A highly enantioselective Strecker reaction of difluoromethyl and trifluoromethyl ketoimines was developed. Remarkable fluorine effect on the reactivity and selectivity is observed and discussed.

A pi-conjugated organogelator (1) was synthesized, and its gelation ability was checked. It was found that it is an excellent gelator for some organic solvents, such as dichloromethane, benzene, o-dichlorobenzene, and DMSO/water. It can self-assemble into 1-D nanofibers induced by hydrogen bonding and pi-pi interactions. Moreover, 1 could form a hybrid gel with C(60)COOH by hydrogen bonds in which 1 and C(60)COOH can act as an electron donor and acceptor, respectively. It was found that the active film from the hybrid 1-D self-assemblies of 1 and C(60)COOH showed remarkably higher photocurrent generation compared with that containing 1 and C(60) because of the construction of interdigitated and ordered assemblies of donors and acceptors.

In this paper, mesoporous nitrogen-doped TiO2 microspheres were prepared by a template-free solvothermal method. The nitrogen-doped TiO2 mesoporous spheres show higher visible-light photocatalytic activity than the undoped TiO2. The dual role of urea helps the formation of a mesoporous structure and the doping of nitrogen into TiO2 to be completed simultaneously during the solvothermal process. The amount of urea shows the crucial effect on the mesoporous structure and nitrogen doping in TiO2.

Hybrid compounds of macrosphelides and epothilones, both of which are natural macrolides having a 16-membered skeleton, were designed and synthesized using a ring-closing metathesis (RCM) strategy. Some of these hybrids were found to exhibit notable apoptosis-inducing activity against human lymphoma cells with higher potency than parent natural macrosphelides, and to be a promising lead compound for development of a new antitumor agent.

Four new silver(I) double salts (L(2)H)(4)[Ag(10)(C(2))(CF(3)CO(2))(12)(L)(2)].5H(2)O (1), [Ag(8)(C(2))(CF(3)CO(2))(6)(L)(6)] (2), [(Ag(2)C(2))(AgC(2)F(5)CO(2))(6)(L)(3)(H(2)O)].H(2)O (3), and (L.H(3)O)(2)[Ag(11)(C(2))(2)(C(2)F(5)CO(2))(9)(H(2)O)(2)].H(2)O (4) incorporating the hitherto unexplored ligand 4-hydroxyquinoline (L) have been synthesized by the hydrothermal method. Compound 1 features an unprecedented bicapped square-antiprismatic Ag(10) silver cage with an embedded C(2)(2-) moiety, whereas the discrete supermolecule 2 bears a rhombohedral Ag(8) core similar to that previously found in Ag(2)C(2).6AgNO(3). Compound 3 contains a discrete supramolecular complex whose core is a (C(2))(2)@Ag(16) double cage constructed from the edge-sharing of two monocapped square antiprisms, which is completely surrounded by 12 pentafluoropropionate, 6 4-hydroxyquinoline, and 2 aqua ligands. The layer structure in 4 is constructed from a sinuous anionic silver column composed of fused irregular monocapped trigonal antiprisms each encapsulating a C(2)(2-) dianion, with L.H(3)O(+) species serving as hydrogen-bond connectors to adjacent columns.

Contrasting behaviors of Rh with Y(La) in the formation of metallofullerenes by excimer laser ablation of metal fullerides C60Rhx and C60Mx (M = La, Y) were observed. For Rh, two sequences of rhodium metallofullerenes, C2nRh and C2n+1Rh with even and odd numbers of carbon atoms, are formed in both the negative and positive ion channels, but for La and Y, only the metallofullerene sequence with even numbers of carbon atoms is formed and only in the positive ion channel. Evidence of the encapsulation of La and Y atoms in fullerene cages forming endohedral fullerenes has been observed, whereas the Rh atom is most probably incorporated into the network of the fullerene cage or pseudo-fullerene forming substitutional metallofullerenes. Density functional theory calculation was performed to determine the structures of the model metallofullerenes C53Rh and C54M (M = Rh and Y). The calculated results are in general consistent with the experimental observations.

The generation of magic number silica clusters [(SiO2)nO2H3]- with n = 4 and 8 by XeCl laser (308 nm) ablation of porous siliceous materials is reported. The production of magic cluster [(SiO2)4O2H3]- can be enhanced by sample selection and experimental optimization so that it becomes the most prominent species in silica clusters. To study the structure of the magic cluster [(SiO2)4O2H3]-, we performed structural optimization for the neutral bare cluster (SiO2)4, the neutral complex cluster (SiO2)4O2H4, and the anionic cluster [(SiO2)4O2H3]- at the HF/6-31G** level. It was found that the ground state of the bare silica tetramer has a linear chain structure whereas a pseudotetrahedral cage-like structural isomer of S4 symmetry is most stable for the complex cluster (SiO2)4O2H4. The stabilization of the three-dimensional (3D) structure can be attributed to the active participation of the O2H4 group in chemical bonding during cluster formation. Our theoretical calculation and bonding analysis indicate that t...