Task Specific Onium Salts and Ionic Liquids as Soluble Supports in Grieco ’s Multicomponent Synthesis of Tetrahydroquinolines

In this work was presented an application of the use of task specific onium salts (TSOSs) as soluble supports in Grieco’s multicomponent synthesis of tetrahydroquinolines. These soluble supports are of wide applicability and combine advantages of solid phase synthesis without its limitations with those of solution phase chemistry. After a simple washing step, products were cleaved from the supports and obtained in pure form and good yields.     

Two-step formation mechanism of<Emphasis Type="Italic"> Acetobacter</Emphasis> cellulosic biofilm: synthesis of sparse and compact cellulose

Classical studies concerning “Acetobacter xylinum” focus on bacterial cellulose “BC” yield and rate in broth, after a long period of incubation (7–14 days). Such observations do not highlight bacterial physiology in the first incubation hours and its impact on BC production. In this study, the growth of a wild strain of Acetobacter was monitored in the first incubation hours. We showed the presence of two different physiologies; the first extends from the incubation moment till the formation of a sparse BC. Sparse BC modifies surface viscosity, and stabilizes hydrodynamic conditions to initiate compact BC production that marks the second physiology. Two containers, of different shapes, were used to confirm our findings, one of which is a culture tube with high drift currents on the broth-air interface, and the other is a conical flask with more stable hydrodynamic conditions at the culture’s surface. We showed that Acetobacter always follows two physiologies independent of the container shape. Logistic model, FTIR, XRD and SEM analysis are used to confirm the results.     

汞(II)与牛血红蛋白相互作用的研究

本文采用紫外光谱(UV/VIS)、荧光光谱和圆二色谱等方法,对汞(II)与牛血红蛋白(BHb)的相互作用进行了研究。结果表明:Hg2 处理导致BHb紫外吸收的增加,出现LMCT带,并随Hg2 浓度的增加LMCT带强度显著增强。BHb分子中Soret带的吸收随着Hg2 作用时间的增加而持续降低,表明Hg2 使部分血红素辅基从BHb中脱离出来。蛋白内源荧光光谱显示,Hg2 与BHb的结合会影响蛋白质的三级结构和四级结构。远紫外圆二色谱表明,Hg2 处理会导致BHb蛋白的α-螺旋含量减少。     

Coordination polymer chains built from CuII and adipate ions linked by hydrogen bonds to form a three‐dimensional framework structure

In the title compound, catena‐poly[bis[(2,2′‐bipyridine‐κ²N,N′)(1,1,3,3‐tetracyano‐2‐ethoxypropenido‐κN)copper(II)]‐μ₄‐hexanedioato‐κ⁶O¹,O^1′:O¹:O⁶,O^6′:O⁶], [Cu₂(C₉H₅N₄O)₂(C₆H₈O₄)(C₁₀H₈N₂)₂]_n, the adipate (hexanedioate) dianion lies across a centre of inversion in the space group P. The Cu^II centre adopts a distorted form of axially elongated (4+2) coordination, and the Cu^II and adipate components form a one‐dimensional coordination polymer from which the 2,2′‐bipyridine and 1,1,3,3‐tetracyano‐2‐ethoxypropenide components are pendent, and where each adipate dianion is bonded to four different Cu^II centres. The coordination polymer chains are linked into a three‐dimensional framework structure by a combination of C—H...N and C—H...O hydrogen bonds, augmented by a π–π stacking interaction.     

Experimental/theoretical electrostatic properties of a styrylquinoline-type HIV-1 integrase inhibitor and its progenitors

We have established that polyhydroxylated styrylquinolines are potent inhibitors of HIV-1 integrase (IN). Among them, we have identified (E)-8-hydroxy-2-[2-(4,5-dihydroxy-3-methoxyphenyl)-ethenyl]-7-quinolinecarboxylic acid (1) as a promising lead. Previous molecular dynamics simulations and docking procedures have shown that the inhibitory activity involves one or two metal cations (Mg2+), which are present in the vicinity of the active center of the enzyme. However, such methods are generally based on a force-field approach and still remain not as reliable as ab initio calculations with extended basis sets on the whole system. To go further in this area, the aim of the present study was to evaluate the predictive ability of the electron density and electrostatic properties in the structure-activity relationships of this class of HIV-1 antiviral drugs. The electron properties of the two chemical progenitors of 1 were derived from both high-resolution X-ray diffraction experiments and ab initio calculations. The twinning phenomenon and solvent disorder were observed during the crystal structure determination of 1. Molecule 1 exhibits a planar s-trans conformation, and a zwitterionic form in the crystalline state is obtained. This geometry was used for ab initio calculations, which were performed to characterize the electronic properties of 1. The electron densities, electrostatic potentials, and atomic charges of 1 and its progenitors are here compared and analyzed. The experimental and theoretical deformation density bond peaks are very comparable for the two progenitors. However, the experimental electrostatic potential is strongly affected by the crystal field and cannot straightforwardly be used as a predictive index. The weak difference in the theoretical electron densities between 1 and its progenitors reveals that each component of 1 conserves its intrinsic properties, an assumption reinforced by a 13C NMR study. This is also shown through an excellent correlation of the atomic charges for the common fragments. The electrostatic potential minima in zwitterionic and nonzwitterionic forms of 1 are discussed in relation with the localization of possible metal chelation sites.     

Efficient barrier properties of mechanically enhanced agro-extracted cellulosic biocomposites

The objective of this work was to prepare the mechanically stable hydrophobic biocomposites by incorporating the cellulose fibers into the polymer matrices for their applications in biomedical and food packaging. Herein, two different types of biocomposites were prepared by mixing polylactic acid (PLA) and polyhydroxybutyrate (PHB) with the agro-extracted cellulose, separately at 170 °C. The influence of the cellulose fibers on the thermal, mechanical, and barrier properties of polymer matrices (PLA and PHB) was observed. With an increase in the cellulose content in PLA and PHB, the tensile strength of the biocomposite materials significantly improved with the enhancement of 24.45% and 32.08%, respectively, compared with the pure PLA and PHB. Furthermore, a decrease of 74.16% and 73.49% in the water vapor transmission rate and oxygen transmission rate, respectively, was observed for cellulose/PHB biocomposites. This study highlights that adding cellulose fibers significantly improves the mechanical and the barrier properties of PLA and PHB, suggesting their biocomposites for use in biodegradable polymer industries.     

Understanding the origin of the enantioselectivity and the mechanism of the asymmetric reduction of ketimine generated from acetophenone with oxazaborolidine catalyst

Structural Chemistry - The enantioselectivity of the oxazaborolidine-catalysed asymmetric reduction reaction of ketimine generated from acetophenone has been investigated by transition state theory...     

Determination of trace elements in coffee beans and instant coffee of various origins by INAA

Summary Extensive use of coffee, by one-third of world's population, entails the evaluation of trace element contents in it. Instrumental neutron activation analysis (INAA) was successfully employed to determine the concentration of 20 trace elements (essential, toxic and nonessential) in four samples of coffee beans of various origins and two instant coffee brands most commonly consumed in Pakistan. This study provides the base-line values of certain toxic and essential elements in coffee. The daily intake of essential and toxic elements through coffee was estimated and compared with the recommended values. The cumulative intake of Mn is four times higher than the recommended value and that of toxic elements is well below the tolerance limits.     

Stereoselective total synthesis of (+)-strictifolione and (6R)-6-[(4R,6R)-4,6-dihydroxy-10-phenyldec-1-enyl]-5,6-dihydro-2H-pyran-2-one by Prins reaction and olefin cross-metathesis

Prins and olefin cross-metathesis reactions were used as the key steps for the stereoselective total synthesis of (+)-strictifolione and (6R)-6-[(4R,6R)-4,6-dihydroxy-10-phenyldec-1-enyl]-5,6-dihydro-2H-pyran-2-one. Removal of MOM protecting groups under neutral conditions using CeCl₃·7H₂O is an attractive addition to the present strategy.     

An In Vitro Study of the Interaction of Copper(II) Salicylates with Genomic DNA Using Gel Electrophoresis and Gel Permeation Chromatography

This papers describes the in vitro interaction of copper(II) acetylsalicylate and copper(II) salicylate with genomic DNA isolated from human blood. The two drug substances were found to bind to DNA after incubation with whole blood over night. Bonding was confirmed by detection of separated DNA electrophoresis bands for copper, copper(II) acetylsalicylate, copper(II) salicylate, acetylsalicylic acid and salicylic acid. Drug–DNA interactions were observed during electrophoresis in the form of fragmentation by formation of two bands when compared to controls. Gel permeation chromatography parameters also confirmed the occurrence of fragmentation. The use of gel permeation chromatography parameters as a measure of fragmentation of DNA is discussed. The fragmentation of genomic DNA after incubation with copper(II) acetylsalicylate and copper(II) salicylate suggested that these drug substances might be responsible for cytotoxicity in vivo.