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The synthesis and structural characterization of an unprecedented asymmetrically modified bivanadium-capped Keggin polyoxometalate (POM) are described. The studies have shown that the high-dimensional assembly of POM-transition metal (TM) cation coordination polymers has depended on a synergic effect of polyoxoanion templates, metal ion coordination geometries and the spacer-lengths of the rigid organic ligands.

Semiconductor CdS and CdSe nanostructures with complex form such as urchin-like nanoflowers, branched nanowires and fractal nanotrees were synthesized via a facile solvothermal approach in a mixed solution made of diethylnetriamine (DETA) and deionized water (DIW). The results showed that the morphologies of CdS and CdSe nanocrystals can be controlled via tuning the volume ratio of DETA and DIW suggesting that the photocatalytic property of CdS nanostructures is related to its unique structural feature.

The Diels-Alder (DA) reactions of various substituted ethenes, styrene and methyl vinyl ketone with omicron-quinone methides are studied by means of density functional theory (DFT). The results indicate that the hydrogen-bond formation between chloroform and the carbonyl oxygen of the omicron-QM lowers the activation energies and increases the asynchronicity.

Research has been conducted on the new heteropoly compounds. The use of elemental, IR and UV analyses in synthesizing and characterizing these compounds is discussed.

The endohedral fullerene [Sc.sub.3]NC@[C.sub.80]-[I.sub.h] is prepared and analyzed, which has an unprecedented planar quinary cluster in a fullerene cage. The intramolecular dynamics in [Sc.sub.3]NC@[C.sub.80]-[I.sub.h] has enabled the whole molecule to exhibit high polarity and ferroelectricity.

The pH value effect on the structures of the Wells-Dawson polyoxometalates (POM)-based coordination polymers is examined. The structural differences have disclosed that the pH value of the reaction system is the main factor affecting the structure and topology of these compounds, which is described by the acid-base chemistry of the molecular building units and silver chemistry.

The flexible organic ligands 1,3-bis(1,2,4-triazol-1-yl)propane (btp), 1,4-bis(1,2,4-triazol-1yl)butane (btb) and 1,6-bis(1,2,4-triazol-1-yl)hexane (btx) are introduced into the Wells-Dawson polyoxometalates (POM) system, which has aimed at obtaining novel architectures of POM coordination polymers with a combination of flexibility and robustness. The structural analyses has shown that the length of flexible bis(triazole) ligands and metal ion coordination geometries have a synergic influence on the structures of this series.

The synthesis of a novel ferromagnetically coupled dimer of [Cu.sup.II]-substituted [gamma]-decatungstosilicate is discussed. Findings reveal the possibility of replacing W atoms with the first-row transition-metal atoms in an already lacunary polyoxometalate (POM).

The flexible 1,1'-(1,4-butanediyl)bis(imidazole) (bbi) ligand is incorporated into the polyoxovanadate system in order to obtain novel polyoxoanion-templated architectures based on [[[As.sub.8][V.sub.14][O.sub.42]].sup.4-] and [[[V.sub.16][O.sub.38]Cl].sup.6-] building blocks. The structural relations have revealed the important template role of the polyoxoanions and the synergetic interactions among the polyoxoanions, transition-metal-ions and flexible ligand in the assembly process.

A microtubes of [alpha]-SiW12, which was fabricated by a template-free simple aqueous reaction, is presented. The formation of the tubes results from a dynamical match of the transformation process of Keggin-type [alpha]-11-series into [alpha]-12-series and the crystal growth of the 12-series.

A three-dimensional (3D) metal-organic framework (MOF), namely, {[Mn4(PBA)4(H2O)6•5H2O]}n (Mn-PBA), has been successfully constructed from 5-(4-pyridin-3-yl-benzoylamino)-isophthalic acid ligand (H2PBA) and Mn(II) ions under solvothermal condition. Structural analysis reveals that there exist 1D hexagonal channels in the 3D structure along the b-axis. Mesoporous Mn3O4/C composites were fabricated by the direct thermolysis of Mn-PBA at 500 °C under an air atmosphere. When tested as a lithium-ion battery anode material, the Mn3O4/C electrode delivers an excellent capacity of 1032 mAh g-1 at 200 mA g-1 after 500 cycles along with remarkable rate capacity, which is supposed to benefit from the unique microspheres characteristic and large accessible specific area. Owing to the good cycling stability and high capacity, the Mn3O4/C electrode can be regarded as a promising anode material for LIBs. [ABSTRACT FROM AUTHOR]

Novel dendron hydrophobically modifiedethoxylated urethanes (DHEUR)with almost the same molecular weights, molecular weight distributions,and identical hydrophilic portion but different terminal hydrophobicgroup numbers were prepared by using Percec-type alkyl substitutedbenzyl alcohol dendrons as new end-cappers. These DHEUR polymers insolution possess interesting associative and rheological behavior.For DHEUR-1with 4-mono(decyloxy)benzyl alcohol (2), the solutions are dominantly composed of the isolatedand separated micelles and exhibit Newtonian behavior in a wide shearrate range accompanied by shear thinning at high shear rate region. DHEUR-2with 3,5-di(decyloxy)benzyl alcohol (4) in solutions form a relatively more complete network through dominantmicellar junctions and process a relatively higher solution viscosityand similar solution viscosity behavior to DHEUR-1. However,shear thinning behavior shifts to a lower shear rate region due toa relatively longer relaxation time. Interestingly, the solutionsof DHEUR-3with 3,4,5-tri(decyloxy)benzyl alcohol (6) have developed a complete physical network and show pronouncedshear thinning behavior over the whole shear rate range. The oscillatorymeasurements further confirm that a gradually developing associativenetwork leads to their different solution rheological behavior, i.e.,viscous fluid (DHEUR-1), viscoelastic fluid (DHEUR-2), and elastic body (DHEUR-3) with increasing the hydrophobictail number of dendrons. Furthermore, the rheological activation energyof these DHEUR polymers increases with the increase of terminal hydrophobicgroup numbers, indicating that DHEUR polymers with more hydrophobictail chains need more energy potential barrier for the disengagementof hydrophobes from micelles due to stronger association strength.In general, the results demonstrate that the terminal hydrophobictail number of dendrons plays a key role in determining the associativeand rheological behavior of DHEUR in solutions. This work opens anew perspective for more efficient thickeners and also promises thepotential of these DHEUR polymers in waterborne coating, cosmetics,dyestuff, medicines, and so on for the first time. [ABSTRACT FROM AUTHOR]

Large-scale metabolomics study requires a quantitative method to generate metabolome data over an extended period with high technical reproducibility. We report a universal metabolome-standard (UMS) method, in conjunction with chemical isotope labeling liquid chromatography-mass spectrometry (LC-MS), to provide long-term analytical reproducibility and facilitate metabolome comparison among different data sets. In this method, UMS of a specific type of sample labeled by an isotope reagent Ls prepared a priori. The UMS is spiked into any individual samples labeled by another form of the isotope reagent in a metabolomics study. The resultant mixture is analyzed by LC-MS to provide relative quantification of the individual sample metabolome to UMS. UMS is independent of a study undertaking as well as the time of analysis and useful for profiling the same type of samples in multiple studies. In this work, the UMS method was developed and applied for a urine metabolomics study of bladder cancer. UMS of human urine was prepared by 13C2-dansyl labeling of a pooled sample from 20 healthy individuals. This method was first used to profile the discovery samples to generate a list of putative biomarkers potentially useful for bladder cancer detection and then used to analyze the verification samples about one year later. Within the discovery sample set, three-month technical reproducibility was examined using a quality control sample and found a mean CV of 13.9% and median CV of 9.4% for all the quantified metabolites. Statistical analysis of the urine metabolome data showed a clear separation between the bladder cancer group and the control group from the discovery samples, which was confirmed by the verification samples. Receiver operating characteristic (ROC) test showed that the area under the curve (AUC) was 0.956 in the discovery data set and 0.935 in the verification data set. These results demonstrated the utility of the UMS method for long-term metabolomics and discovering potential metabolite biomarkers for diagnosis of bladder cancer. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of microtubes of SiMoW11 Keggin polyoxometalates containing either an Mo(V) or Mo(VI) atom is reported. The introduction of a Mo atom into the Keggin-type tungstosilicate microtubes endows them with new properties. The Mo-substituted microtubes may exert both W and Mo functionalities in electrocatalytic reactions and in the immobilization of noble metal nanoparticles. The degree of reduction of the Mo component in the SiMoW11 microtubes is controllable simply by tuning the amount of reductant present in the mother liquor. Mo-substituted Keggin tungstosilicate microtubes in their reduced state are more stable than the all-tungsten Keggin tungstosilicate heteropoly blue microtubes. [ABSTRACT FROM AUTHOR]

A new compound based on the Wells–Dawson polyoxometalate, Ag7(bbi)5(OH)(P2W18O62) (bbi = 1,1′-(1,4-butanediyl)bis(imidazole)) (1), has been hydrothermally synthesized and characterized by the normal physical methods and single-crystal X-ray diffraction. Compound 1represents the first interpenetrating framework based on the Wells–Dawson POMs. The AgI···AgIinteractions are crucial in the formation of the two individual motifs: in the first interpenetrating motif, the supported {Ag2}2瘩麮 and the P2W18polyanions form an infinite inorganic chain, then the Ag骉 and bbi ligands extend the chain to form a three-dimensional framework. The second motif is constructed by the Ag–bbi meso-helix chains which are stitched by the unsupported Ag7···Ag7 dimers to form a two-dimensional layer with huge loops. The electrochemical study exhibits that compound 1could be used as electrocatalyst in the electrical reductions of bromate. In addition, compound 1shows a photocatalytic action for degradation of RhB. [ABSTRACT FROM AUTHOR]

By employing the polyoxometalates (POMs) with different sizes as structural motifs, three new organic−inorganic hybrids based on the multiply Cu-bipy coordination polymeric chain-modified POMs, [Cu(bipy)]2[HPMo12O40] (1), {[Cu(bipy)]4[GeW12O40]}·H2O (2), and {[Cu(bipy)]4[Mo15O47]}·2H2O (3) (bipy = 4,4′-bipyridine), have been hydrothermally synthesized and characterized by routine physical methods. Compound 1exhibits 1D chain in which Keggin POMs are modified by bitrack Cu-bipy chains. Compound 2represents a 2D layer of tetra-track Cu-bipy chain modified Keggin POMs. And compound 3shows an infinite-track Cu-bipy chain-modified molybdenum oxides 3D structure, namely, a modifying state of high point. Because the differences of POMs affect the structures of the hybridsthe number of Cu-bipy chains from bi- to infinite-track, and the dimension from 1D to 3Dtheir successful isolation demonstrates that members of the vast family of POMs may be employed as structural motifs in designing more solid-state materials. Additionally, their electrochemical properties have been studied. [ABSTRACT FROM AUTHOR]

By introducing the flexible 1,1′-(1,4-butanediyl)bis(imidazole) (bbi) ligand into the polyoxovanadate system, five novel polyoxoanion-templated architectures based on [As8V14O42]4- and (V16O38Cl]6- building blocks were obtained: [M(bbi)2]2[As8V14O42(H2O)] [M = Co (1), Ni (2), and Zn (3)], [Cu(bbi)]4[As8V14O42(H2O)] (4), and [Cu-(bbi)]6[V16O38Cl] (5). Compounds 1-3 are isostructural, and they exhibit a binodal (4,6)-connected 2D structure with Schläfli symbol (34·4²)(34·44·54·6³)2, in which the polyoxoanion induces a closed four-membered circuit of M4(bbi)4. Compound 4 exhibits an interesting 3D framework constructed from tetradentate [As8V14O42]4- cluster anions and cationic ladderlike double chains. There exists a bigger M8(bbi)6O2 circuit in 4. The 3D extended structure of 5 is composed of heptadentate [V16O38Cl]6- anions and flexural cationic chains; the latter consists of six Cu(bbi) segments arranged alternately. It presents the largest 24-membered circuit of M24(bbi)24 so far observed made of bbi molecules and transition-metal cations. Investigation of their structural relations shows the important template role of the polyoxoanions and the synergetic interactions among the polyoxoanioris, transition-metal ions, and flexible ligand in the assembly process. The magnetic properties of compounds 1-3 were also studied. [ABSTRACT FROM AUTHOR]

Asymmetric, regio- and stereoselective alternating copolymerization of CO2 and racemic aliphatic epoxides proceeds effectively under mild temperature and pressure by using a binary catalyst system of a chiral tetradentate Schiff base cobalt complex [SaIenCoIIIX] as the electrophile in conjunction with an ionic organic ammonium salt or a sterically hindered strong organic base as the nucleophile. The substituent groups on the aromatic rings, chiral diamine backbone, and axial X group of the electrophile, as well as the nucleophilicity, leaving ability, and coordination ability of the nucleophile, all significantly affect the catalyst activity, polymer selectivity, enantioselectivity, and stereochemistry. A bulky chiral cyclohexenediimine backbone complex [SaIcyCoIIIX] with an axial X group of poor leaving ability as the electrophile, combined with a bulky nuclephile with poor leaving ability and low coordination ability, is an ideal binary catalyst system for the copolymerization of CO2 and a racemic aliphatic epoxide to selectively produce polycarbonates with relatively high enantioselectivity, >95% head-to-tail connectivity, and >99% carbonate linkages. A fast copolymerization of CO2 and epoxides was observed when the concentration of the electrophile or/and the nucleophile was increased, and the number of polycarbonate chains was proportional to the concentration of the nucleophile. Electrospray ionization mass spectrometry, in combination with a kinetic study, showed that the copolymerization involved the coordination activation of the monomer by the electrophile and polymer chain growth predominately occurring in the nucleophile. Both the enantiomorphic site effect resulting from the chiral electrophile and the polymer chain end effect mainly from the bulky nucleophile cooperatively control the stereochemistry of the CO2/epoxide copolymerization. [ABSTRACT FROM AUTHOR]

The endohedral fullerene Sc3NC@C80-Ih has been synthesized and characterized; it has an unprecedented planar quinary cluster in a fullerene cage. It is also the first chemical compound in which the presence of an unprecedented (NC)3- trianion has been disclosed. The fascinating intramolecular dynamics in Sc3NC@C80-Ih enables the whole molecule to display high polarity and promising ferroelectricity. This finding inspires the possibility that such a planar quinary cluster may be useful in constructing many other endohedral fullerenes. [ABSTRACT FROM AUTHOR]

Asymmetric aza-Heck cyclization and coupling reactions offer efficient access to enantioenriched N -heterocycles, yet the current studies focus primarily on sequential C-N and C-C bond formation. Herein, we report an enantioselective reductive aza-Heck cyclization followed by a C-S coupling sequence, ultimately yielding sulfide-containing enantioenriched pyrrolines. The reaction is conducted under mild conditions and tolerates broad functionalities including alkynes, phenols, anilines, amides, nitriles, and bromides.

The digestion and absorption of different structural lipids in human milk may be different. Hence, by simulating in vitro infant digestion and Caco-2 cells to explore the effects of 1-oleoyl-2-palmitoyl-3-linoleoylglycerol (OPL)/1,3-dilinoleoyl-2-palmitoylglycerol (LPL)/1,3-dioleoyl-2-palmitoylglycerol (OPO) and their mixtures (M) (OPL/LPL/OPO in M1, M2, and M3 were 1.5/0.5/1, 1.2/1.2/1, and 0.5/0.2/1, respectively) on digestion and absorption. The digestibility of the OPO group was higher than those of the OPL and LPL groups, and the M3 group was higher than the M1 and M2 groups. The synthesis and transport of triglycerides in Caco-2 cells in OPL and LPL groups were higher than the OPO group, and the M1 group was significantly higher than that of M3. The expression of FABP1, PPARα, and MTT protein in OPL and M1 groups was significantly higher than OPO and M3, respectively. There are differences in the digestion and absorption of differently structured lipids from this study.

The influence of different reaction conditions on the yield of syringaldehyde was studied by using perovskite oxide as the catalyst. The optimal reaction conditions are as follows: 0.60 g of dealkali lignin, 0.60 g of 5 wt % theta ring-loaded LaFe 0.2 Cu 0.8 O 3 catalyst, 30 mL of 1.0 mol/L NaOH solution, 160 °C reaction temperature, 0.80 MPa O 2 pressure, and 2.5 h reaction time. Under these conditions, the highest syringaldehyde yield was 10.00%. The recycling performance of the catalyst was studied. It was found by XRD analysis that the catalyst maintained high catalytic activity after four times of use., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Glucokinase (GK) activity, which is rapidly regulated by glucokinase regulatory protein (GKRP) in the liver, is crucial for blood glucose homeostasis. In this paper, the GK activation mechanisms of 1-deoxynojrimycin (DNJ), resveratrol (RES), oxyresveratrol (OXY), cyanidin-3-glucoside (C3G), and cyanidin-3-rutinoside (C3R) were compared. The results revealed that DNJ, RES, C3G, and C3R could differently improve glucose consumption and enhance intracellular GK activities. DNJ and RES significantly promoted GK translocation at 12.5 μM, whereas other ingredients showed moderate effects. DNJ, C3G, and C3R could rupture intramolecular hydrogen bonds of GK to accelerate its allosteric activation at early stage. RES and OXY could bind to a "hydrophobic pocket" on GK to stabilize the active GK at the final stage. Otherwise, RES, OXY, C3G, and C3R could interact with GKRP at the F1P binding site to promote GK dissociation and translocation. Enzymatic assay showed that RES (15-50 μM) and OXY (25-50 μM) could significantly enhance GK activities, which was caused by their binding properties with GK. Moreover, the most dramatic up-regulation effects on GK expression were observed in C3G and C3R groups. This work expounded the differences between GK activation mechanisms, and the new findings would help to develop new GK activators.

Bamboo leaf extract as a food additive has been used for preventing the oxidation of food. In the present study, we investigated the influence of Phyllostachys edulis leaf extract on starch digestion. Orientin, isoorientin, vitexin, and isovitexin were determined as its α-amylase inhibitory constituents. An inhibitory kinetics experiment demonstrated that they competitively inhibit α-amylase with Ki values of respectively 152.6, 11.5, 569.6, and 75.8 μg/mL. Molecular docking showed the four flavones can interact with the active site of α-amylase, and their inhibitory activity was greatly influenced by the glucoside linking position and 3'-hydroxyl. Moreover, the results of starch-iodine complex spectroscopy, X-ray diffraction, and scanning electron microscopy indicated that P. edulis flavonoids retard the digestion of starch not only through interaction with digestive enzymes, but also through interaction with starch. Thus, P. edulis leaf extract can be potentially used as a starch-based food additive for adjusting postprandial hyperglycemia.

The endohedral fullerene Sc(3)NC@C(80)-I(h) has been synthesized and characterized; it has an unprecedented planar quinary cluster in a fullerene cage. It is also the first chemical compound in which the presence of an unprecedented (NC)(3-) trianion has been disclosed. The fascinating intramolecular dynamics in Sc(3)NC@C(80)-I(h) enables the whole molecule to display high polarity and promising ferroelectricity. This finding inspires the possibility that such a planar quinary cluster may be useful in constructing many other endohedral fullerenes.

The knowledge of C-COOH homolytic bond dissociation enthalpies (BDEs) is of great importance in understanding various chemical and biochemical processes involving the decarboxylation reaction. In the present study, the density functional theory (DFT method), B3P86/6-311++G(2df,2p)//B3LYP/6-31+G(d), is found to be reliable to predict the C-COOH BDE of various structurally unrelated carboxylic acids. The mean absolute deviation (MAD) and root-mean-square deviation (rmsd) of this optimal method are equal to 2.0 and 2.5 kcal/mol, respectively. With the authorized theoretical protocol in hand, an extensive C-COOH BDE scale containing over 100 carboxylic acids has been established. The availability of this body of data enabled a detailed investigation of remote substituent effect on four types of carboxylic acids, including para-substituted benzoic acid, beta-substituted cis-propenoic acid, beta-substituted trans-propenoic acid, and substituted propiolic acid. Also with the C-COOH BDE data obtained in this work, an excellent linear relationship has been found between the C-COOH BDE of carboxylic acids and the C-H BDE of their hydrocarbon analogues. After comparing the energy barrier of the Pd-catalyzed decarboxylation reaction (DeltaG(decarboxylation)++) with the related C-COOH BDE, a negative correlation between the DeltaG(decarboxylation)++ and the C-COOH BDE was found.

Wurtzite CdS and CdSe nanostructures with complex morphologies such as urchin-like CdS nanoflowers, branched nanowires, and fractal nanotrees can be produced via a facile solvothermal approach in a mixed solution made of diethylenetriamine (DETA) and deionized water (DIW). The morphologies of CdS and CdSe nanocrystals can be easily controlled via tuning the volume ratio of DETA and DIW. Urchin-like CdS nanoflowers made of CdS nanorods are in a form of highly ordered hierarchical structures, while the nanowires are branched nanowires, and the fractal CdS nanotrees are a buildup of branched nanopines. The results demonstrated that solvothermal reaction in a mixed amine/water can access a variety of complex morphologies of semiconductor materials. The photocatalytic activity of CdS particles with different morphologies has been tested by the degradation of acid fuchsine under both UV and visible light, showing that the as-prepared branched CdS nanowires exhibit high photocatalytic activity for degradation of acid fuchsine.