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  • Open access
  • 18 Reads
Morphological and chemical analysis of the molecularly-imprinted polymer-based D-arabinose sensor on a modified electrode with functionalized carbon nanotubes

The development of renewable fuels is driven by different countries due to future shortages of fossil fuels and damage to the environment caused by their use. A promising alternative to replace the growing energy crisis and reduce environmental damage is second generation ethanol, which can be produced from sugarcane-based lignocellulosic biomass, an excellent raw material with high availability and abundance that does not cause competition with energy sources. Second generation production, generally characterized by preprocessing, hydrolysis and fermentation, is not as advanced as first generation production. However, with continuous scientific effort, this change can be altered. A clear understanding of the chemical changes that occur through hydrolysis of lignocellulosic biomass is critical to process control and optimization. In this sense, the development of graphite and paraffin composite sensors, modified with carbon nanotubes (FMWCNTs) and molecularly printed polymers (MIPs) for the determination of D-arabinose is an excellent option, because these sensors have high selectivity and sensitivity in the analyzes.For this reason, the present work presents a chemical study of the functional groups of the chemical species present on the surfaces of the materials using the Fourier Transform Infrared Spectroscopy (FTIR) technique and a morphological analysis by the Scanning Electron Microscopy (SEM) technique.

  • Open access
  • 16 Reads
Synthesis and characterization of new biocompatible amino amphiphilic compounds derived from oleic acid as nanovectors for drug delivery

Amphiphilic molecules have been actively explored as promising materials in the field of bio and nanotechnology. These molecules are constituted by a polar head and a lipophilic tail and in an aqueous medium are self-assemble to form different types of macromolecular structures such as micelles, monolayer vesicles, bars, sheets and tubes. In this work, a convergent synthetic approach for the synthesis of two new amphiphilic compounds based on a versatile amino polar head, a tetraethylene glycol spacer and a lipophilic tail derived from oleic acid has been developed. Subsequently, after a self-assembly process in aqueous medium, nanostructures as micelles have been obtained and characterized. Finally, a procedure for the inclusion of the highly lipophilic drug Dexamethasone has been carried out in order to study the ability of these micelles to act as nanovectors for drug delivery.

  • Open access
  • 9 Reads

ZnBr2 functionalized ionic liquid: An efficient solvent and catalyst for the facile synthesis of 1-benzamino-1,4-dihydropyridine

Hamid Reza Esmaili Zand, Maede Kazemnezhad Leili, Hossein Ghafuri

Ionic liquids (ILs) are mostly composed of organic cations and organic/inorganic anions. One of the most important classes of ILs are imidazolium ILs. [1]. The hydrophilicity and hydrophobicity of ILs are regbenzohydrazidularly influenced by the length of alkyl side chain of cation. According to this effect, better hydrophilicity comes from a shorter alkyl side chain and on the contrary, better hydrophobicity comes from a lengthier alkyl side chain of cation. Typical ILs have exceptional properties. Most ILs are stable at about 300 oC in the liquid state at normal conditions. Due to the exceptional properties of ILs, they have been used in diverse industries including batteries and fuels. As solvents, ILs have been employed in many chemical fields. Solubilities of ILs with organic/inorganic species are completely satisfactory. Here, by N-methyl imidazole (Im), 1,3-dibromopropane, triethanolamine (TEA), and ZnBr2, new ionic liquid (TEA-Im-Zn) was synthesized and used as catalyst and solvent in the synthesis of functionalized 1-benzamino-1,4-dihydropyridine using aromatic aldehyde, malononitrile, triethylamine, arylamine and dialkyl acetylenedicarboxylate.

  • Open access
  • 6 Reads
Use of PPh3-BrCCl3 in the preparation of acylhydrazines, N-methylamides, anilides and N-arylmaleimides from carboxylic acids
Abdullah Al-Hemyari, Areej Hashim, Muna Bufaroosha, Thies Thiemann

In certain countries, many of the reagents used to transform carboxylic acids to acyl halides such as phosphorus trichloride, phosphorus tribromide, phosphorus pentachloride, phosphoryl chloride, thionyl chloride and sulfuryl chloride are difficult to come by. Against this background, the authors developed the reaction system triphenylphosphine (PPh3) – bromotrichloromethane (BrCCl3) to prepare acyl halides in situ. In the following, the use of this reagent combination is joined with the reaction of the in situ prepared acyl halides with nitrogen nucleophiles, specifically with hydrazines, methylamine and anilines. The reaction is also used in an intramolecular variant by the reaction of maleanilic acids to N-arylmaleimides.

  • Open access
  • 11 Reads
Deuteration of alkenes with NaBD4/AcOD in presence of Pd on carbon
Fatima Aljunaibi, Hanan Aldhanhani, Halima Alawani, Amnah Al Hmoudi, Abdullah Al-Hemyari, Thies Thiemann

Activated alkenes such as cinnamates and chalcones can easily be converted to 2,3-dideuterio-arylpropionates and dideuteriochalcones, respectively, by the action of NaBD4, AcOD in the presence of Pd on carbon. Toluene or benzene was used as solvent. It was shown that Pd on carbon was necessary for the reaction to proceed. Deuterium addition experiments were also carried out with NaBD4, AcOD, D2O in the presence of Pd on carbon

  • Open access
  • 13 Reads
Synthesis of novel Schiff base Derivates containing a fragment of the HIV Integrase Inhibitor drug Raltegravir
CARLOS CORTES-GARCIA, Jairo Rojas-Ortiz, Claudia Contreras-Celedón, Mario Gómez-Hurtado, Luis Chacón- García

An eco-friendly methodology for the synthesis of novel Schiff base analogs of Raltegravir, an integrase inhibitor drug, is described. Thus, pertinence of these imine derivatives is related to Medicinal Chemistry to develop new anti-HIV compounds. Based on thorough search of the relevant literature, this is the first report of the synthesis of Schiff base using a Raltegravir drug fragment as amino component. In addition, these imines will be used as a synthetic precursor to prepare other biologically relevant nitrogen heterocycles, such as 1,5-disubstituted tetrazoles.

  • Open access
  • 18 Reads
Synthesis of 1,3-oxazoles via Van Leusen reaction in a pressure reactor and preliminary studies of cations recognition
CARLOS CORTES-GARCIA, Veronica García-Ramírez, Claudia Contreras-Celedón, Gabriela Rodriguez-García, Luis Chacón- García

Six 1,3-oxazoles were synthetized in moderate to good yields by Van Leusen reaction in a pressure reactor. The methodology allowed to decrease the reaction times reported in the literature from hours to 20 minutes. In addition, preliminary qualitative recognition of cations with some synthetized oxazoles such as Hg2+, Ni2+, Zn2+, Ag+, Cu2+, Pb2+ was done and a “turn off” effect was observed with Ni2+. Finally, the 1,3-oxazoles could be of biological relevance because they are considered privileged nucleus in medicinal chemistry and therefore will be useful to obtain pharmacophoric hybrid molecules.

  • Open access
  • 12 Reads
Aqueous micellary systems formed by surfactant ionic liquids. Application in Diels-Alder reactions.
Claudia Della Rosa, Claudia Adam

In the present work, our objective is to take advantage of the property presented by Ionic Liquids (ILs) based on 1-alkyl-3-methylimidazolium cations by having amphiphilic character when the alkyl group is a long hydrocarbon chain. These ILs can act as surfactants forming micelles in aqueous solution. In this sense, the micellar effect on a Diels-Alder reaction (DA) was analyzed taken as a reference. The reactive system studied consists of maleic anhydride and isoprene, variables such as diene:dienophile ratio and reaction temperatura among the most important were optimized. N, N-dodecylmethylimidazolium bromide was used at the critical micellar concentration (CMC) of 1 x 10-2 M.

These “new systems” microheterogeneous would allow, in addition to better solubilization of non-polar substrates, to adopt milder reaction conditions.

  • Open access
  • 5 Reads
Structure-Based Site of Metabolism (SOM) prediction of ligand for CYP3A4 Enzyme: Comparison of Glide XP and Induced Fit Docking (IFD)

Metabolism is one of the prime reasons where most of the drugs fail to accomplish their clinical trials. The enzyme CYP3A4, which belongs to the superfamily of cytochrome P450 enzymes (CYP) helps in the metabolism of a large number of drugs in the body. The enzyme CYP3A4 catalyzes mainly the oxidative chemical processes and also shows a very broad range of ligand specificity. Understanding of compound’s structure where oxidation would take place is crucial for the successful modification of molecules in order to avoid unwanted metabolism and to increase its bioavailability. For this reason, it is required to know the site of metabolism (SOM) of the compounds, where compounds undergo enzymatic oxidation. It can be identified by predicting the accessibility of the substrate’s atom toward oxygenated Fe atom of heme in a CYP protein. The CYP3A4 enzyme is a highly flexible enzyme and can take significantly different conformations depending on the ligand with which it is being bound. Here in, we studied the ability of the Glide XP and Induced Fit docking (IFD) tool of Schrodinger software suite to reproduce the binding mode of co-crystalized ligands into six X-ray crystallographic structures. We extend our studies for the prediction of SOM for compounds whose experimental SOM is reported but ligand-enzyme complex crystal structure is not available in Protein Data Bank (PDB). It was observed that IFD reproduces the exact binding mode of available co-crystallized structures and correctly predicted the SOM of experimentally reported compounds.

  • Open access
  • 7 Reads
SYNTHESIS OF PRECERAMIC ORGANOMAGNESIUMOXANE ALUMOXANE SILOXANES
Galina Shcherbakova, Anastasiya Pokhorenko

Organomagnesiumoxane alumoxane siloxane oligomers with different Al:Mg and Al:Si molar ratio have been synthesized through ethylacetoacetate alkoxyhydroxyalumoxane oligomers co-condensation with magnesium acetylacetonate and oligoethoxysiloxanes in organic solvents (alcohol, toluene) at a temperature of 70 – 100 ºС within 3 – 6 hours with the following solvent distillation. The physicochemical properties of the synthesized oligomers were studied. It is shown that with a molar ratio of Al:Mg ≈ 2 and Al:Si ≈ 1, oligomers have fiber-forming properties. The process of thermotransformation of organomagnesiumoxane alumoxane siloxanes into ceramic phases is investigated. It is found that pyrolysis results in the formation of multicomponent ceramics based on magnesium, aluminum, and silicon oxides, in particular, ceramics with a composition close to that of cordierite 2MgO·2Al2O3·5SiO2 (Mg2Al4Si5O18) or a mixed composition: magnesium-aluminum spinel and mullite.

Therefore, the synthesized organomagnesiumoxane alumoxane siloxanes are preceramic oligomers and can be used as precursors for the preparation of various components (binders, impregnating compositions, fibers, ceramic powders) of high-purity ceramic composites based on magnesium, aluminum and silicon oxides.

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