Study on the BODIPY-triazine-based tripod fluorescent systems: various structures from similar procedure

We report a small library of fluorophore-triazine tripod fluorescent system that can accommodate a combination of three different functional groups, such as fluorophore (BODIPY), ligand (or ligands) and auxiliary group. Syntheses, photophysical properties as well as binding properties towards metal ions of these BODIPY-triazine derivatives are described.     

Synthesis, structure, and activity evaluation of two silver(I) complexes as Helicobacter pylori urease inhibitors

Two silver(I) compounds, [Ag(R,R-hxn)](C₇H₄BrO₂) · 2H₂O (I) (Chxn = 1,2-diaminocyclohexane) and [Ag(C₅H₆N₂)₂]₂(C₈H₄O₄) · 10H₂O (II), were synthesized and complex I was structurally characterized by X-ray crystallography. Compound I contains a catena-(trans-1,2-diaminocyclohexane) silver polycation ([Ag(Chxn)]_∞) in a roughly linear fashion, while II possesses a linear-type silver monocation. Compounds I and II were evaluated for their inhibitory activities against Helicobacter pylori urease in vitro. Both were found to have strong inhibitory activities against H. pylori urease comparable to that of acetohydroxamic acid.     

Microwave solid phase synthesis, characterization, and antimicrobial activity of 3,5-diiodo-salicylalidene-glycine-cobalt(II)

One mononuclear complex, C₉H₇I₂NO₄Co(II) (I) with 3,5-diiodo-salicylalidene, glycine and Co(CH₃COO)₂ · 4H₂O were microwave solid synthesized. The complex was characterized by X-ray crystallography, UV, IR, ESI-MS, and elemental analyses. In addition, further investigation revealed that the central cobalt(II) atom in complex is five-coordinated by one nitrogen atom and four oxygen atoms. The complex was assayed for antibacterial (B. subtilis, S. aureus, S. faecalis, P. aeruginosa, E. coli, and E. cloacae) activities by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl trtrazolium bromide) method. Complex I showed favorable antimicrobial activity with MICs of 3.125, 6.25, 6.25, 6.25, 3.125, and 6.25 μg/mL against B. subtilis, S. aureus, S. faecalis, P. aeruginosa, E. coli, and E. cloacae, respectively.     

Detection of layer‐by‐layer self‐assembly multilayer films by low‐temperature plasma mass spectrometry

The detection of layer‐by‐layer self‐assembly multilayer films was carried out using low‐temperature plasma (LTP) mass spectrometry (MS) under ambient conditions. These multilayer films have been prepared on quartz plates through the alternate assembling of oppositely charged 4‐aminothiophenol (4‐ATP) capped Au particles and thioglycolic acid (TGA) capped Ag particles. An LTP probe was used for direct desorption and ionization of chemical components on the films. Without the complicated sample preparation, the structure information of 4‐ATP and TGA on films was studied by LTP‐MS. Characteristic ions of 4‐ATP (M) and TGA (F), including [M]^+?, [M‐NH₂]⁺, [M‐HCN‐H]⁺, and [F + H]⁺, [F‐H]⁺, [F‐OH]⁺, [F‐COOH]⁺ were recorded by LTP‐MS on the films. However, [M‐CS‐H]⁺ and [F‐SH]⁺ could not be observed on the film, which were detected in the neat sample. In addition, the semi‐quantitative analysis of chemical components on monolayer film was carried out, and the amounts of 4‐ATP and TGA on monolayer surface were 45 ng/mm² and 54 ng/mm², respectively. This resulted the ionization efficiencies of 72% for 4‐ATP and 54% for TGA. In order to evaluate the reliability of present LTP‐MS, the correlations between this approach and some traditional methods, such as UV–vis spectroscopy, atomic force microscope and X‐ray photoelectron spectroscopy were studied, which resulted the correlation coefficients of higher than 0.9776. The results indicated that this technique can be used for analyzing the films without any pretreatment, which possesses great potential in the studies of self‐assembly multilayer films. Copyright © 2013 John Wiley & Sons, Ltd.     

Biochemical and Structural Studies of Conserved Maf Proteins Revealed Nucleotide Pyrophosphatases with a Preference for Modified Nucleotides

1. Download : Download high-res image (165KB)
2. Download : Download full-size image

     

Composition heterogeneity of tetrafluoroethylene-hexafluoropropylene random copolymers characterized by successive self-nucleation and annealing

In the present work, successive self-nucleation and annealing (SSA) was applied to a series of tetrafluoroethylene-hexafluoropropylene random copolymers (FEPs). Multiple melting peaks were observed for all FEP samples after SSA thermal treatment. The lamellar crystal thicknesses were calculated from the melting temperatures, and the mass percentages of the crystals of specific thickness were obtained from the areas of the melting peaks. As a result, distributions of the lamellar thickness, which can be correlated to the composition distribution, were determined. It was found that the composition distribution of the FEP samples tended to become more heterogeneous as the content of hexafluoropropylene (HFP) comonomer increases. Samples with the same HFP content might also have different composition distributions.     

Dihydromyricetin

A study on the efficiency of bio-based compound as stabilizer for linear low density polyethylene (LLDPE) is reported. A water extract from Ampelopsis grossedentata (Dihydromyricetin) is used. Its stabilizing activity is compared with two commercial phenolic antioxidants: methyl gallate (MG) and Irganox 1010. Based on the measurement of the oxidation onset temperature (OOT) of LLDPE/antioxidant samples, it is found that the antioxidant ability of the three kinds of antioxidants is in the following order: DMY > 1010 > MG. The antioxidant ability and thermal decomposition activation energy (E _a) of antioxidants are further examined by thermal gravimetric analysis. The effects of water extraction on the migration resistance of LLDPE/antioxidants are also evaluated by monitoring the OOT change, demonstrating that DMY retained high stability against migration.     

Determination of the standard molar enthalpy of formation of the ternary complex of neodymium with vitamin B3 and 8-hydroxylquinoline by microcalorimetry

A novel solid ternary complex, [Nd(C₆H₄NO₂)₂·C₉H₆NO·2H₂O], was synthesized in a water bath (333.15 K) by three kinds of reagents: neodymium chloride, vitamin B3 (C₆H₅NO₂), and 8-hydroxylquinoline (C₉H₇NO). Its composition and structure were characterized by elemental analysis, IR spectra, UV spectra, molar conductance, and thermogravimetric analysis. During the process of coordination, C₆H₅NO₂ was bidentate-coordinated with Nd³⁺ in the form of an acidic group by removing the proton; hydroxyl oxygen atom and heterocyclic nitrogen atom of C₉H₇NO formed a chelate ring. Particularly, in this article, a thermochemical cycle in the calorimetric solvent (V _HCl:V _DMF:V _EtOH = 3:1:1) was designed on the basis of Hess’s law. At 298.15 K, the dissolution enthalpies of the reactants and products were determined by a advanced solution–reaction isoperibol microcalorimeter, respectively. According to the above results and relevant literature data, the standard molar enthalpy of formation of [Nd(C₆H₄NO₂)₂·C₉H₆NO·2H₂O], was estimated to be $ \Updelta_{f} H_{m}^{\Uptheta} $ [[Nd(C₆H₄NO₂)₂·C₉H₆NO·2H₂O(s)], 298.15 K] = ?(2,129.1 ± 2.5) kJ mol^?1.     

Influences of levofloxacin salts on the metabolism of Escherichia coli by microcalorimetry

A microcalorimetric technique was used to evaluate the influence of both Levofloxacin lactate in sodium chloride injection (drug A) and Levofloxacin hydrochloride in sodium chloride injection (drug B) on the metabolism of Escherichia coli. By means of an isothermal calorimeter and ampoule method at 37 °C, the power-time curves of E. coli growth were obtained under different conditions. The parameters such as the growth rate constant k, maximum power output P _m, time t _m corresponding to the maximum power output and inhibitory ratio I of these two drugs were obtained. The results reveal that the inhibitory abilities enhance with increasing concentrations of the two drugs. The critical growth concentration and the half-inhibitory concentration IC₅₀ were 0.15 and 0.079 μg mL^?1 (for drug A), 0.13 and 0.061 μg mL^?1 (for drug B), respectively. These results show the drug A has slightly better inhibitory effect on E. coli than that of drug B.     

Melting of pentaerythritol tetranitrate (PETN) nanoconfined in controlled pore glasses (CPG)

The melting temperature depression of pentaerythritol tetranitrate, nanoconfined in controlled pore glasses (CPG), was systematically studied by differential scanning calorimetry (DSC). The solid–liquid interfacial energy σ _sl was obtained from the Gibbs–Thomson equation fit to melting temperature vs. reciprocal pore diameter. The pore size distribution of the CPG pores was also estimated from the DSC data. Pore sizes obtained from the manufacturer by BET are compared with those determined from the DSC curves using either the curves directly or by assuming spherical shaped confining cavities. The thermal mass vales are in better agreement with the BET estimation.