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We report special square-nanosheet flowers with an ammonium vanadate phase, which are synthesised by choosing an appropriate solvent system (ethanol aqueous solution) and reductant (octadecylamine (ODA)) under solvothermal conditions. For the synthesis mechanism, a reduction reaction (phase transformation) takes place, where the raw material, NH 4 VO 3 , transforms to an intermediate, NH 4 V 3 O 8 , and then to the target ammonium vanadate phase. The ethanol aqueous solvent promotes the oriented growth of the two-dimensional crystal. ODA serves as the reductant and is responsible for the low vanadium valence in the product. By treating these new ammonium vanadate flowers during the hydrothermal reaction, the growth of VO 2 (B) net-like nanosheets can be realised. To the best of our knowledge, there is no information available on this ammonium vanadate nanostructure and its transformation into VO 2 (B). This new ammonium vanadate two-dimensional assembly material can be applied as an anode material for the Li-ion batteries and exhibits a reversible electrochemical capacity of 817 mhA g −1 after 130 cycles at 1 A g −1 , as well as a good rate performance. The findings in this study have important implications for the synthesis and application of ammonium vanadate and vanadium oxide bronze nanostructures. [ABSTRACT FROM AUTHOR]

A mild and straightforward synthetic protocol for construction of a furan skeleton promoted by Yb(OTf)3 from β-ketothioamides and arylglyoxals has been developed at room temperature. Importantly, this protocol involves a tandem sequence that includes aldol condensation, N-cyclization, ring opening, O-cyclization, S-cyclization, and Eschenmoser sulfide contraction. [ABSTRACT FROM AUTHOR]

Regioselective synthesis of functionalized tetrahydrobenzo[b]pyrans has been developed by multicomponent reactions (MCRs) and tandem [3 + 3] annulations of β-benzoylthioacetanilides or β-(2-haloaroyl)thioacetanilides as valuable sources with aromatic aldehydes and 5,5-dimethyl-1,3-cyclohexanedione catalyzed by triethylamine. This MCR followed by a postcondensation cyclization via an intramolecular SNAr in the presence of K2CO3 led to an unprecedented novel chromeno[2,3-b]quinoline framework containing an important chromene moiety in good yields. The reactions were very mild, convenient, and o-selective to form new fused tetracyclic target molecules. [ABSTRACT FROM AUTHOR]

A sequential one-pot two-step protocol for microwave-assisted synthesis of Hantzsch-type hexa-substituted 1,4-dihydropyridines has been developed. The three-component reactions of β-aroylthioamides with aldehydes and acetonitrile derivatives produce the intermediates in situ followed by a S-alkylation to afford hexa-substituted 1,4-dihydropyridines. The reaction presumably proceeds via a Knoevenagel condensation−Michael addition−cyclocondensation−rearrangement−S N2 reaction sequence. Target compounds were obtained in high yields and simply purified by recrystallization. The novel method is complementary to the classical Hantzsch synthesis in that it is well-suited to the preparation of hexa-substituted 1,4-dihydropyridines. [ABSTRACT FROM AUTHOR]

The unexpectedly high reactivity of a (2-benzoxazolyl) per-O-benzoyl--d-thioglucoside and related donors in reactions promoted by copper(II) trifluoromethanesulfonate is revealed, by comparison with the unreactive -anomer, to be the result of neighboring group participation. Revision of the armed−disarmed concept for glycosyl donors is not required. [ABSTRACT FROM AUTHOR]

Density functional theory together with Car-Parrinello ab initio molecular dynamics simulation has been used to investigate the free energy profiles (FEP) of monomer capture in Grubbs- and SHOP-type olefin polymerization catalysts. The FEPs along the reaction coordinates at 300 K were determined directly by a point wise thermodynamic integration technique. Comparison between potential energy profile (PEP) and the FEP has been made. The results show that, for both catalysts, the PEP for the monomer ethylene uptake by the metal center is a typical Morse curve without energy barrier. However, a small barrier (1.8 kcal/mol for Grubbs catalyst and 2.4 kcal/mol for SHOP catalyst) exists on the FEP. The π complexation energy on the FES at 300 K is higher by 10–12 kcal/mol over that on the PES. The differences between FES and PES are due to entropy contribution. Slow growth simulations on the ethylene capture process show that the ethylene attacks the metal center by an asynchronous mode. This indicates that the forming of the π-bonding between the metal and ethylene is initiated by electrophilic attack of the metal to one of the ethylene carbons. © 2006 Wiley Periodicals, Inc. J Comput Chem 28: 513–518, 2007 [ABSTRACT FROM AUTHOR]

A series of rhenium(V) complexes, [(X)(ReO)(dt)(PPh3)] and [(o-SC8H4PPh2)(ReO)(mtp)], were prepared to explore electronic effects on the C-S cleavage reaction that occurs upon reaction with PAr3 at ambient temperature [where X = S(C6H4-p-Z) (Z = OMe, Me, H, F, Cl), OPh, Cl, and SC2H5, and dt is the chelating dithiolate ligand derived from 2-(mercaptomethyl)thiophenol, 1 ,2-ethanedithiol, 1,3-propanedithiol, 1 ,3-butanedithiol, and 2,4-pentanedithiol]. The scope and selectivity of the C—S activation were examined. The C—S bond cleavage to form metallacyclic Re(V) complexes with a Re≡S core occurs only for the complexes with mtp and pdt frameworks and X = SAr and SC2H5. The difference in reactivity is due to the different donating abilities of ancillary and dithiolate ligands, especially their π-donating ability, which plays a critical role in C—S activation. The kinetics of the C—S activation process was determined; nucleophilic attack of PPh3 on the oxo group of the RevO core appears to be the rate-controlling step. The reaction is accelerated by electron-poor ArS ligands, but is unaffected by the substituents on phosphines. A detailed mechanistic study is presented. The results represent a rare example of migration of alkanethiolate leading to the formation of alkylthiolato complexes. [ABSTRACT FROM AUTHOR]

A series of new 7-cyano-6-phenyl-2-aryl-1H-imidazo[1,2-b]pyrazoles (5) by the cyclocondensation reactions between 5-amino-4-cyano-3-phenyl-1H-pyrazole (1) and α-bromoacetophenones (3) or α-tosyloxyacetophenones (2) obtained by the reactions of acetophenones with [hydroxy(tosyloxy)iodo]benzene (HTIB) have been synthesized in good yields, and the intermediates 5-amino-4-cyano-6-phenyl-1-(aroylmethyl)pyrazoles (4) were isolated as a potent evidence for the regioselectivity. The syntheses of 4 and 5 have been achieved successfully through the procedure involving α-tosyloxyacetophenones and some through the procedure involving α-bromoacetophenones. When utilizing α-tosyloxyacetophenones, the reactions were more eco-friendly, the reaction time was significantly reduced, and the synthetic procedure was more convenient and easier to manipulate. [ABSTRACT FROM AUTHOR]

The reaction of O(3P) with ClONO2 were studied by means of the density functional method at the B3PW91/6-31G(d) level and the correlation energy correction method at the MP2/6-311G(2df) level. Geometries, energies, and vibrational frequencies of reactants, transition states, intermediates and products for the examined reaction were examined. The reliable energies were also computed by employing the quadratic CI calculation at the QCISD/6-311G(2df) level. The reaction mechanism was investigated. [Copyright &y& Elsevier]

Simpterpenoid A (1), an unprecedented meroterpenoid possessing a highly functionalized cyclohexadiene moiety (ring C) featuring gem-propane-1,2-dione and methylformate groups, was characterized from mangrove-derived Penicillium simplicissimum MA-332. Due to the highly oxygenated and functionalized ring C and lack of some key correlations, the unambiguous assignment of the planar structure and steric configuration was solved by X-ray crystallographic analysis. Compound 1 exhibited inhibitory activity against influenza neuraminidase in nanomolar quantities. [ABSTRACT FROM AUTHOR]

Five new sesquiterpenoids (I)-(V) (nardosinanone A-E) are isolated from the title species. [ABSTRACT FROM AUTHOR]

Ambient ionization mass spectrometry is achieved in a simple maimer by loading a sample solution onto a corner of a microscope cover glass positioned in front of the inlet to a mass spectrometer and applying a high voltage to the sample. The resulting stream of charged droplets is stable, has no contamination from the substrate platform, and can be used repeatedly. The utility of droplet spray for in situ analysis and real-time monitoring of chemical reactions was demonstrated by the bis(cyclopentadienyl)zirconium dichloride (zirconocene dichloride)/methylaluminoxane, Cp2ZrCl2/MAO, homogeneously catalyzed polymerization of ethylene in various solutions. Reaction times ranged from seconds to minutes, and catalytically active species and polymeric products of ethylene were acquired and identified by tandem mass spectrometry. [ABSTRACT FROM AUTHOR]

The existence of a complex relationship between soil microbes and ginsenoside contents in their host plants has been reported by previous studies. Here, we analyzed the interaction between the root pathogens and the ginsenoside content in the roots of American ginseng. Two fungal pathogen species were isolated from diseased American ginseng roots, and identified as Fusarium oxysporum (isolate C1) and Fusarium solani (isolate F19) by molecular sequencing analysis. To determine the effect of Fusarium-mediated infection of American ginseng roots, the contents of three ginsenosides, ginsenosides Rb, ginsenosides Re and ginsenosides Rg, were monitored over a time course of 120 h post infection using high performance liquid chromatography (HPLC). We found that the level of Rb was rapidly upregulated upon fungal infection, whereas the contents of Re or Rg were not altered significantly. Furthermore, the presence of Rb, but not Re or Rg, significantly inhibited conidium germination of both Fusarium species. Thus, Rb is likely the disease-resistance compound produced by American ginseng roots in response to the pathogenic fungi. Our study is the first to report the three ginsenosides with different chemical structure respond differently to soilborne pathogen infection. [ABSTRACT FROM AUTHOR]

Two new kinds of tetrahydrobenzo[b]imidazo[3,2, I-(,][l ,8]naphthyridine derivatives have been successfully synthesized by cascade reactions including Knoevenagel condensation, aza-ene reaction, imine-enamine tautomerization, cyclocondensation, and intramolecular SNAr of precursors 2-(2-chloroaroyl)methylene- imidazolidines with aromatic aldehydes and ethyl acetoacetate or Meidrum's acid under mild conditions, respectively. These studies highlighted the concept of a substrate-design approach to the development of novel multicomponent reactions by simply incorporating an o-halo group into the aryl ring of 2-benzoyl- methyleneimidazolidine as new synthons. In this domino reaction, at least six different active sites are involved; two C-C bonds, two C-N bonds, and two new rings are constructed with all reactants efficiently utilized in the chemical transformation. [ABSTRACT FROM AUTHOR]

Synthesis of nanocrystals with exposed high-energy facets is a well-known challenge in many fields of science and technology. The higher reactivity of these facets simultaneously makes them desirable catalysts for sluggish chemical reactions and leads to their small populations in an equilibrated crystal. Using anatase TiO2 as an example, we demonstrate a facile approach for creating high-surface-area stable nanosheets comprising nearly 100% exposed (001) facets, Our approach relies on spontaneous assembly of the nanosheets into three-dimensional hierarchical spheres, which stabilizes them from collapse. We show that the high surface density of exposed TiO2 (001) facets leads to fast lithium insertion/deinsertion processes in batteries that mimic features seen in high-power electrochemical capacitors. [ABSTRACT FROM AUTHOR]

The reaction of MnBr2 and [PPN)2[S,S-C6H3-R] (1:2 molar ratio) in THF yielded [(THF)Mn(S,S-C6H3-R)2]- [R = H (1a), Me (1b); THF tetrahydrofuran]. Formation of the dimeric (Mn(S,S-C6H3-R)2]22- [R = H (2a), Me (2b)] was presumed to compensate for the electron-deficient MnIII core via two thiolate bridges upon dissolution of complexes la and 1b in CH2CI2. Complex 2a displays antiferromagnetic coupling interaction between two MnIII centers (J = -52 cm-1), with the effective magnetic moment (μeff) increasing from 0.85 μB at 2.0 K to 4.86 μB at 300 K. The dianionic manganese(ll) thiolate complexes [Mn(S,S-C6H3-R)2]2- [R = H (3a), Me (3b)] were isolated upon the addition of [BH4]- into complexes 1a and 1b or complexes 2a and 2b, respectively. The anionic mononuclear {Mn(NO)}5 thiolatonitrosylmanganese complexes [(NO)Mn(S,S-C6H3-R)2}- [R = H (4a), Me (4b)] were obtained from the reaction of NO(g) with the anionic complexes la and lb, respectively, and the subsequent reduction of complexes 4a and 4b yielded the mononuclear {Mn(NO)}6 [(NO)Mn(S,S-C6H3-R)2]2- [R = H (5a), Me (5b)]. X-ray structural data, magnetic susceptibility measurement, and magnetic fitting results imply that the electronic structure of complex 4a is best described as a resonance hybrid of [(L)(L)MnlllNO)]- and [(L)(L)MnIII(NO-)]- (L = 1,2-benzenedithiolate) electronic arrangements in a square-pyramidal ligand field. The lower IR VNO stretching frequency of complex 5a, compared to that of complex 4a (shifting from 1729 cm-1 in 4a to 1651 cm-1 in 5a), supports that one-electron reduction occurs in the {(L)(L)Mnlll} core upon reduction of complex 4a. [ABSTRACT FROM AUTHOR]

A new in situlow-temperature, low-pressure hydrothermal condensation reaction of amino diphosphonic acids affords a series of phosphonate derivatives with bicyclic structures. By using such bicyclic phosphonate ligands, three compounds, namely, [Zn 2(L 1)(phen) 4]·12H 2O ( 1), [Ni(Im) 6] 3(L 2) 2(ImH) 2·24H 2O ( 2), and [Cu 2(L 3)(phen) 2(H 2O) 2]·9H 2O ( 3) (phen = 1,10-phenanthroline, Im = imidazole, L 1H 4, L 2H 4, and L 3H 4represent different bicyclic phosphonate derivatives), have been synthesized and structurally characterized by single-crystal X-ray crystallography. Novel water clusters with different structural motifs, such as T4(3)5(0)A0 water tape in 1, TU water tape in 2, and L5(4)5(5)15(14) water layer in 3, are discussed in detail. The coordination mode of the metal ion and the use of the appropriate second ligand, which would influence the reaction and structures of the final products are also discussed. [ABSTRACT FROM AUTHOR]

Presents an online transient moving chemical reaction boundary method to stack ionizable analytes in high-salt matrix in capillary zone electrophoresis. Increase in separation efficiency; Values of relative standard deviation peak height, peak area and migrating time; Effect on isotachophoresis.

Chiral bifunctional sulfamides were found to be highly efficient organocatalysts for the conjugate addition of aldehydes to nitroolefins in the presence of base additives. [ABSTRACT FROM AUTHOR]

The structure and Li+ ion dynamics of a new class of ABO3 perovskite with Li on both the A- and B-sites are described. La3Li3W2O12 is synthesized by solid state reaction at 900 °C and shown by powder X-ray diffraction to adopt the structure of a monoclinic double perovskite (A2)BB′O6, (La1.5Li0.5)WLiO6, with rock salt order of W6+ and Li+ on the B-site. High resolution powder neutron diffraction locates A-site Li in a distorted tetrahedron displaced from the conventional perovskite A-site, which differs considerably from the sites occupied by Li in the well studied La2/3-xLi3xTiO3 family. This is confirmed by the observation of a lower coordinated Li+ ion in the 6Li magic angle spinning nuclear magnetic resonance (NMR) spectra, in addition to the B-site LiO6, and supported computationally by density functional theory (DFT), which also suggests local order of A-site La3+ and Li+. DFT shows that the vacancies necessary for transport can arise from Frenkel or La excess defects, with an energetic cost of ∼0.4 eV/vacancy in both cases. Ab initio molecular dynamics establishes that the Li+ ion dynamics occur by a pathway involving a series of multiple localized Li hops between two neighboring A-sites with an overall energy barrier of ∼0.25 eV, with additional possible pathways involving Li exchange between the A- and B-sites. A similar activation energy for Li+ ion mobility (∼0.3 eV) was obtained from variable temperature 6Li and 7Li line narrowing and relaxometry NMR experiments, suggesting that the barrier to Li hopping between sites in La3Li3W2O12 is comparable to the best oxide Li+ ion conductors. AC impedance-derived conductivities confirm that Li+ ions are mobile but that the long-range Li+ diffusion has a higher barrier (∼0.5 eV) which may be associated with blocking of transport by A-site La3+ ions. [ABSTRACT FROM AUTHOR]

As opposed to the reversible redox reaction ({Fe(NO)2}10 reduced-form DNIC [(NO)2Fe(S(CH2)3S)]2− ( 1)⇌{Fe(NO)2}9 oxidized-form [(NO)2Fe(S(CH2)3S)]−), the chemical oxidation of the {Fe(NO)2}10 DNIC [(NO)2Fe(S(CH2)2S)]2− ( 2) generates the dinuclear {Fe(NO)2}9-{Fe(NO)2}9 complex [(NO)2Fe(μ-SC2H4S)2Fe(NO)2]2− ( 3) bridged by two terminal [SC2H4S]2− ligands. On the basis of the Fe K-edge pre-edge energy and S K-edge XAS, the oxidation of complex 1 yielding [(NO)2Fe(S(CH2)3S)]− is predominantly a metal-based oxidation. The smaller S1-Fe1-S2 bond angle of 94.1(1)° observed in complex 1 (S1-Fe1-S2 88.6(1)° in complex 2), compared to the bigger bond angle of 100.9(1)° in the {Fe(NO)2}9 DNIC [(NO)2Fe(S(CH2)3S)]−, may be ascribed to the electron-rich {Fe(NO)2}10 DNIC preferring a restricted bite angle to alleviate the electronic donation of the chelating thiolate to the electron-rich {Fe(NO)2}10 core. The extended transition state and natural orbitals for chemical valence (ETS-NOCV) analysis on the edt-/pdt-chelated {Fe(NO)2}9 and {Fe(NO)2}10 DNICs demonstrates how two key bonding interactions, that is, a FeS covalent σ bond and thiolate to the Fe d [ABSTRACT FROM AUTHOR]

To seek the effect that condition of the complexes has on the manufacture of the biaryl compounds, seven Ni(II) complexes, namely, {[Ni(L)0.5(bpa)(H2O)]·2H2O}n (1), {[Ni2(L)(dpp)2(H2O)]·4H2O}n (2), {[Ni(L)0.5(pbmb)(H2O)]·H2O}n (3), {[Ni2(L)(bmp)2(H2O)]·7H2O}n (4), {[Ni(L)0.5(pbib)1.5]·2H2O}n (5), {[Ni2(L)(pbib)1.5]·3H2O}n (6), and [Ni(L)0.5(beb)2(H2O)]n (7) (bpa = 1,2-bis(4-pyridyl)ethane, dpp = 1,3-di(4-pyridyl)propane, pbmb = 1,1′-(1,3-propane)bis(2-methylbenzimidazole), bmp = 1,5-bis(2-methylbenzimidazol) pentane, pbib = 1,4-bis(imidazol-1-ylmethyl)benzene, beb = 1,4-bis(2-ethylbenzimidazol-1-ylmethyl)benzene), have been gained through hydro(solvo)thermal reactions of 5,5′-(hexane-1,6-diyl)-bis(oxy)diisophthalic acid ligand (H4L) with Ni(II) metal ions under the regulation and control of six N-donor ligands. 3-fold interpenetrating complex 1 belongs to a (4,4)-connected 3D bbf net with a vertex symbol of (64·8²)(66) topology. 3-fold interpenetrating complex 2 presents a (4,4,4)-connected 3D bbf net with a Schläfli symbol of (66)2(64·8²) topology. 3 features a (3,4)-connected 3,4L13 topology with a Schläfli symbol of (4·6²)(4²·6²·8²) topology. 4 possesses a (4,4,4)-connected mog Moganite 3D network fabric, and the vertex symbol is (4·64·8)2(4²·6²·8²). 5 takes on a (4,5)-connected architecture, and the point symbol is (4·69)(4²·66·8²). 6 is a (4,7)-connected framework, and the Schläfli symbol is (45·5)(47·5³·611). 7 has a (4,4)-connected 4,4L28 topology, and the point (Schläfli) symbol is (4²·64)(4·64·8). A systematic structural comparison of 1-7 signifies that their frameworks can be regulated through varied conformations of the flexible H4L ligand and diverse N-donor ligands. Between the proximal Ni(II) ions, the variable-temperature (2-300 K) magnetic susceptibilities of 6 display overall weak antiferromagnetic coupling. In the complexes-catalyzed homocoupling reaction of iodobenzene, 3, 5, 6, and 7 have been verified to be effectual catalysts for the synthesis of the biaryl compounds. [ABSTRACT FROM AUTHOR]

A novel copper-catalyzed tandem C-S/C-C bond-forming reaction of 2-biaryl isothiocyanates with diaryliodonium salts was developed. This is the first general approach to synthesize phenanthridines from 2-biaryl isothiocyanates. This methodology has been successfully applied to the synthesis of trisphaeridine. [ABSTRACT FROM AUTHOR]

The title compound, C33H29N, was obtained by the reaction of 9-chloro­methyl­anthracene and n-propyl­amine. Two anthra­cenyl­methyl units are linked to the N atom of n-propyl­amine and the dihedral angle between the two anthracene systems is 64.3 (2)°. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance imaging (SPRi) is one of the powerful tools for immunoassays with advantages of label-free, real-time, and high-throughput; however, it often suffers from limited sensitivity. Herein we report a dual signal amplification strategy utilizing polydopamine (PDA) functionalization of reduced graphene oxide (PDA-rGO) nanosheets for sensitive SPRi immunoassay in serum. The PDA-rGO nanosheet is synthesized by oxidative polymerization of dopamine in a gentle alkaline solution in the presence of graphene oxide (GO) sheets and then is antibody-conjugated via a spontaneous reaction between the protein and the PDA component. In the dual amplification mode, the first signal comes from capture of the antibody-conjugated PDA-rGO to form sandwiched immunocomplexes on the SPRi chip, followed by a PDA-induced spontaneous gold reductive deposition on PDA-rGO to further enhance the SPRi signal. The detection limit as low as 500 pg mL-1 is achieved on a nonfouling SPRi chip widi high specificity and a wide dynamic range for a model biomarker, carcinoembryonic antigen (CEA) in 10% human serum. [ABSTRACT FROM AUTHOR]

Unique quadridentate salen type triple-decker dinuclear sandwich ytterbium complex [Yb2L3(CH3OH)]·0.5H2O (1) and triple-decker trinuclear sandwich ytterbium complex [Yb3L3(CH3OH)2(NO3)3]·CH3OH·5H2O (2) are isolated from the reactions of Yb(OAc)3·4H2O and Yb(NO3)3·6H2O with H2L, respectively (H2L = N,N′-bis(salicylidene)-1,2-(phenylene-diamine)). Complex 2could be harvested from the addition of complex 1and Yb(NO3)3·6H2O. Near infrared (NIR) lanthanide luminescence and the lifetime of complexes 1and 2are conducted and described. [ABSTRACT FROM AUTHOR]

Seeded emulsion polymerization of n-butyl acrylate (n-BA) was initiated by a redox initiator system: cumene hydroperoxide/ferrous sulfate hexahydrate/ethylene-diaminetetraacetic acid monosodium salt/sodium formaldehyde sulfoxylate (CHP−Fe2+−EDTA−SFS). Final poly(n-butylacrylate) (PBA) particles with narrow size distribution were obtained. The kinetics and mechanism of seeded emulsion polymerization initiated by the redox initiator system were investigated. Special care was focused on effects of component concentration of the redox initiator system on the seeded emulsion polymerization kinetics. Particle growth and pH variation during the polymerization were also studied. It was found that the polymerization rate and the overall conversion increased with increasing CHP and SFS concentration. Interestingly, the optimal molar ratio of CHP/SFS was 1.10/3.81 rather than being equimolar in our work. In addition, an optimal molar ratio of EDTA to ferrous ions (2.19 × 10−5mol/7.12 × 10−6mol) was found. The polymerization rate increased first and then decreased with increases in ferrous ion concentration. The pH value in the system decreased as the polymerization proceeded. A limiting conversion phenomenon of conversion not being able to exceed 20% was found, and an explanation to the limiting conversion was proposed on the basis of the views of the practical cumulative formation constant log KMYand reaction rate comparison. When another activator solution (EDTA/FES/SFS (mol) 2.19 × 10−5/7.12 × 10−6/1.91 × 10−3) was added, the limiting conversion was removed and the final conversion reached 97%. [ABSTRACT FROM AUTHOR]

Two 3D supramolecular architectures, [Cu(tmbdc)(NH3)2] n, 1, (tmbdc = 2,3,5,6-tetramethylbenzenedicarboxylate), and {[Cu3(btc)2(NH3)6(H2O)]·2H2O} n, 2, (btc = 1,3,5-benzenetricarboxylate) have been assembled with 1D or 2D coordination polymers as supramolecular synthons. The geometry matching of the moieties is the key factor for the formation of the two supramolecular architectures by the cooperation of coordination bonds, hydrogen bonds and π···π interactions. Crystal data for 1: Formula CuC12H18N2O4, monoclinic, space group P21/c, a = 9.0134(5), b = 10.8785(5), c = 6.4702(3) Å, β = 91.679(1)°, V = 634.15(5) Å3, Z = 2, R1 = 0.0251 and wR2 = 0.0722. Crystal data for 2: Formula Cu3C18H30N6O15, monoclinic, space group C2/c, a = 13.9213(5), b = 17.1210(6), c = 12.5271(5) Å, β = 114.779(1)°, V = 2710.89(17) Å3, Z = 4, R1 = 0.0245 and wR2 = 0.0665. The positions and isotropic displacement parameters of all the hydrogen atoms are refined. The geometry matching of the moieties of 1D or 2D coordination polymers leads to the formation of two 3D supramolecular architectures by the cooperation of coordination bonds, hydrogen bonds and π⋯π interactions. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The synthesis, characterization, and transformation of the anionic (Fe(NO)2)9 dinitrosyl iron complexes (DNICs) [(NO)2Fe(ONO)2]- (1), [(NO)2Fe(OPh)2]- (2), [(NO)2Fe(OPh)(C3H3N2)]- (3) (C3H3N2=imidazolate), [(NO)2Fe-(OPh)(-SC4H3S)]- (4), [(NO)2Fe(p-OPhF)2]- (5), and [(NO)2Fe(SPh)(ONO)]- (6) were investigated. The binding affinity of ligands ((SPh]-, [-SC4H3S]-, [C3H3N2]-, [OPh]-, and [NO2]) toward the (Fe(NO)2)9 motif follows the ligand-displacement series [SPh]- ∼ [-SC4H3S]- > [C3H3N2]- > [OPh]- > [NO2]-. The findings, the pre-edge energy derived from the is → 3d transition in a distorted Td environment of the Fe center falling within the range of 7113.4-7113.8 eV for the anionic (Fe(NO)2)9 DNICs, implicate that the iron metal center of DNICs is tailored to minimize the electronic changes accompanying changes in coordinated ligands. Our results bridging the ligand-substitution reaction study and X-ray absorption spectroscopy study of the electronic richness of the (Fe(NO)2)9 core may point the way to understanding the reasons for nature's choice of combinations of cysteine, histidine, and tyrosine in protein-bound DNIC5 and rationalize that most DNIC5 characterized/proposed nowadays are bound to the proteins almost through the thiolate groups of cysteinate/glutalhione side chains in biological systems. [ABSTRACT FROM AUTHOR]

Ergot alkaloids are toxins and important pharmaceuticals that are produced biotechnologically on an industrial scale. The first committed step of ergot alkaloid biosynthesis is catalyzed by dimethylallyl tryptophan synthase (DMATS; EC 2.5.1.34). Orthologs of DMATS are found in many fungal genomes. We report here the x-ray structure of DMATS, determined at a resolution of 1.76 Å. A complex of DMATS from Aspergillus fumigatus with its aromatic substrate L-tryptophan and with an analogue of its isoprenoid substrate dimethylallyl diphosphate reveals the structural basis of this enzyme-catalyzed Friedel-Crafts reaction, which shows strict regiospecificity for position 4 of the indole nucleus of tryptophan as well as unusual independence of the presence of Mg2+ ions. The 3D structure of DMATS belongs to a rare β/α barrel fold, called prenyltransferase barrel, that was recently discovered in a small group of bacterial enzymes with no sequence similarity to DMATS. These bacterial enzymes catalyze the prenylation of aromatic substrates in the biosynthesis of secondary metabolites (i.e., a reaction similar to that of DMATS). [ABSTRACT FROM AUTHOR]

A simple and practical one-step method for the screening of new titanium catalysts for olefin polymerization has been developed, which allows to combine ligands such as enamine and salicylaldehyde-derived imines with TiCl 4(THF) 2in situfor direct activity evaluation. By this strategy, β-carbonylenamine made TiCl 4(THF) 2, a highly active and single-site-like catalyst for ethylene polymerization and copolymerization. A rationale involving a newly formed titanium complex that was characterized by X-ray analysis is discussed. [ABSTRACT FROM AUTHOR]

A novel phosphorus derivative was synthesized through HTVS. The title compounds were confirmed by MS, 1H NMR, 31P NMR. The DOCK was also studied. [ABSTRACT FROM AUTHOR]

The first asymmetric synthesis of novel, potent photore active γ-secretase inhibitors 2 and 3 has been accomplished. Two stereoselective methods for the preparation of lactone 9 are described. Protected benzophenone inter- mediate 19 is prepared via an aldol-elimination reaction followed by a PtO2-catalyzed asymmetric hydrogenation. Two routes leading from 19 to compounds 2 and 3 are evaluated. The application of 3 as an activity-based probe has been demonstrated by localizing y-secretase activity in the plasma membrane of intact cells. [ABSTRACT FROM AUTHOR]

The left ends of the biosynthetic gene clusters of novobiocin (nov), clorobiocin (clo) and coumermycin A1 (cou) from Streptomyces spheroides (syn. S. caeruleus) NCIMB 11891, S. roseochromogenes var. oscitans DS 12.976 and S. rishiriensis DSM 40489 were cloned and sequenced. Sequence comparison suggested that novE, cloE and couE, respectively, represent the borders of these three clusters. Inactivation of novE proved that novE does not have an essential catalytic role in novobiocin biosynthesis, but is likely to have a regulatory function. The gene products of novF and cloF show sequence similarity to prephenate dehydrogenase and may produce 4-hydroxyphenylpyruvate (4HPP) as a precursor of the substituted benzoate moiety of novobiocin and clorobiocin. Coumermycin A1 does not contain this benzoate moiety, and correspondingly the coumermycin cluster was found not to contain a functional novF homologue. The coumermycin biosynthetic gene cluster apparently evolved from an ancestral cluster similar to those of novobiocin and clorobiocin, and parts of the ancestral novF homologue have been deleted in this process. No homologue to novC was identified in the gene clusters of clorobiocin and coumermycin, questioning the postulated involvement of novC in aminocoumarin biosynthesis. Heterologous expression of novDEFGHIJK in Streptomyces lividans resulted in the formation of 2,4-dihydroxy-α-oxy-phenylacetic acid, suggesting that at least one of the proteins encoded by these genes may participate in a hydroxylation reaction. [ABSTRACT FROM AUTHOR]

The title compound, C9H12N2O3, was synthesized by the reaction in ethanol of ethane-1,2-di­amine and 3-[bis­(methyl­thio)­methyl­ene]-6-methyl-3,4,5,6-tetra­hydro-2 H-pyran-2,4-dione. Two intramolecular N—H⋯O hydrogen bonds induce a high degree of planarity. [ABSTRACT FROM AUTHOR]

The title compound, C27H27N3O2S, was obtained via a multicomponent reaction using benzaldehyde, ethyl aceto­acetate, ammonium acetate and phenyl isothio­cyanate. The pyrimidine ring assumes a half-boat conformation. The crystal packing is stabilized by N—H⋯O and N—H⋯S hydrogen bonds. The phenyl group of the anilinocarbonothioyl group displays some rotational disorder. [ABSTRACT FROM AUTHOR]

In the crystal structure of the title compound, C19H20O2S2, the mol­ecules form stacks along the b axis, with short inter­molecular S⋯C distances of 3.453 (3) and 3.560 (3) Å. Weak inter­molecular C—H⋯O inter­actions provide further stabilization of the crystal packing. [ABSTRACT FROM AUTHOR]