PREDICTION OF PREDOMINANT CONFIGURATION IN THE ENANTIOSELECTIVE REDUCTION OF -KETOACID DERIVATES WITH BAKER'S YEAST USING NEURAL NETWORKS

International audienceCorrelation between chemical structure and enantioselectivity in baker's yeast reduction of a set of carbonyl compounds was constructed by means of a multi-layer neural network using the back-propagation algorithm. To evaluate the predictive power of the neural network (NN) model, the cross-validation procedure was used, 88 % of the reactions were correctly predicted

POLY(AMINOMETHYLENEPHOSPHONIC) ACID FOR SOLVENT EXTRACTION OF METAL IONS

Diaminododecyltetramethylenetetraphosphonic acid (DADTMTPA) has been investigated in liquid - liquid extraction of Zn (II) and Cu (II) in acetate media. The extraction of both cations was carried out in different media with the addition of CH3COONa, CH3COOH, HCl and H2SO4 at different pH values. The maximum extraction yield for copper is 70% after addition of 10 mg of sodium acetate and for zinc is 30% after addition of acetic acid at pHi = 5.5, in one step

Computational study of the chemical reactivity properties of bis (trimethyl tetrathiafulvalenyl) thiophene

The chemical reactivity of four bis (trimethyltetrathiafulvalenyl) thiophene is determined by its potential (electronic) energy (hyper) surface. All the quantum chemical calculations have been carried out using DFT level of theory, B3LYP functional and 6-31G(d,p) as basis set. Molecular electrostatic potential (MEP) and HOMO-LUMO energy levels have been performed. The local reactivity descriptor such as Fukui function is also performed to determine the reactive sites within the title molecules. The chemometric methods PCA and HCA were employed to find the subset of variables that could correctly classify the compounds according to their reactivity

CATALYSIS BY TRIFLIC ACID: SYNTHESIS OF THE INDOLYLQUINONES AS POTENTIAL ANTITUMOR AGENT

International audienceTrifluoromethanesulfonic acid catalyzes efficiently the conjugate addition of indoles to p-benzoquinones under mild conditions affording the corresponding indolylquinones in high yields with high selectivity. In particular the poorly reactive menadione underwent reaction with indoles under similar conditions to give 3-indolylnaphthoquinones

New dicationic piperidinium hexafluorophosphate ILs, synthesis, characterization and dielectric measurements

AbstractA new class of dicationic ionic liquids (ILs) were synthesized for electrochemical applications at high temperatures. The syntheses are based on a dialkylation reaction of N-alkylpiperidine followed by anion exchange. The structures of ILs, based on piperidinium combined with hexafluorophosphate anion, were identified by using 1H, 13C, 19F, 31P NMR and FT-IR spectroscopy. ILs’ thermal properties were investigated in the temperature range from −50 to 350°C by using differential scanning calorimetry (DSC). In the frequency of 10−2–106Hz range, dielectric measurements were performed on ILs’ samples at various temperatures from −80 to 20°C, i.e. around the glass transition temperature. The peak relaxation was observed near to this temperature. Also, the conductivity was investigated and the energy activation determined. The temperature dependence of the relaxation times was shown to be governed by the Arrhenius equation

Synthesis and proton conduction properties of lanthanide amino-sulfophosphonates

Crystalline acid-functionalized metal phosphonates are potential candidates as proton conducting electrolytes. Their frameworks can be chemically modified to contain proton carriers such as acidic groups (P-OH; -SO3H, -COOH,…) and guest molecules (H2O, NH3,…) that generates hydrogen bond networks stable in a wide range of temperature [1,2]. In this work, focus is laid on properties derived from the combination of lanthanide ions with the amino-sulfophosphonate ligand (H2O3PCH2)2-N-(CH2)2-SO3H. Hightrough-put screening was followed to reach the optimal synthesis conditions under solvothermal conditions at 140 ºC. Isolated polycrystalline solids, Ln[(O3PCH2)2-NH-(CH2)2-SO3H].2H2O (Ln= La, Pr and Sm), crystallize in the monoclinic (La) and orthorhombic (Pr and Sm) systems with unit cell volume of ~2548 Å3. Preliminary proton conductivity measurements for Sm derivative have been carried out between 25º and 80 ºC at relative humidity (RH) values of 70 % and 95 %. The sample exhibits enhanced conductivity at high RH and T (Figure 1) and constant activation energies of 0.4 eV, typical of a Grothuss mechanism of proton.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. FQM-1656; MAT2013-41836-

Structural and quantum chemical studies on aryl sulfonyl piperazine derivatives

The optimized molecular structure and electronic features of aryl sulfonyl piperazine derivatives 1-4 have been investigated theoretically using Gaussian 09 software package and DFT/B3LYP method with 6-31G (d,p) basis set. The reactivity of the title molecules was investigated and both the positive and negative centers of the molecules were identified using molecular electrostatic potential (MEP) analysis which the results illustrate that the regions reveal the negative electrostatic potential are localized in sulfamide function while the regions presenting the positive potential are localized in the hydrogen atoms. The energies of the frontier molecular orbitals and LUMO-HOMO energy gap are measured to explain the electronic transitions. Global reactivity parameters of the aryl sulfonyl piperazine derivatives molecules were predicted to find that the more reactive and softest compound is the compound 3. Mulliken’s net charges have been calculated and results show that 3N is the more negative and 33S is the more positive charge, which Indicates extensive charge delocalization in the entire molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization (π→π transitions) has been analyzed using NBO analysis. Fist hyperpolarizability is calculated in order to find its importance in non-linear optics and the results show that the studied molecules have not the NLO applications. Keywords: sulfamide; density functional theory; computational chemistry; electronic structure; quantum chemical calculations

Determination of Reactive Properties of a Series of Mono-Functionalized Bis-tetrathiafulvalene Employing DFT Calculations

Density functional Theory (DFT) calculations at the B3LYP/6-31G (d,p) level of theory are carried out to investigate the equilibrium geometry of the novel compounds 3(a-e). Moreover, The Molecular electrostatic Potential (MEP) analysis reveals the sites for electrophilic attack and nucleophilic reactions within the molecules. Additionally, the reactivity and reactive site within the mono-functionalized bis-tetrathiafulvalenes, dipole moment, theoretical study of the electronic structure, nonlinear optical properties (NLO), and natural bonding orbital (NBO) analysis are performed and discussed

Tuning Proton Conductivity Properties of Lanthanide Amino-Sulfophosphonates-Loaded Nafion Composite Membranes

Polymer-based electrolytes in proton exchange membrane fuel cells (PEMFCs) utilize acidic groups as proton carriers and hydrogen bonding networks as proton-conducting pathways to facilitate proton transport. Crystalline acid-functionalized metal phosphonates are potential proton conductors while maintaining a high hydration degree below 100 °C. This property may be combined with Nafion-like polymers which tend to dehydrate at the operating conditions of PEMFCs [1,2]. In this work, preliminary results of the preparation of lanthanide amino-sulfophosphonates-loaded Nafion composites membranes and the corresponding electrical properties are reported. Synthesis conditions of lanthanide derivatives were optimized following a hightrough-put screening at 140 °C. Their crystal structures, solved from synchrotron X-ray powder diffraction data, corresponds to layered frameworks where the acidic groups, -CPO3H or -SO3H, point toward the interlamellar region interacting by H-bond with the lattice water. The composites were prepared by mixing the metal phosphonates with Nafion solution at different loadings. The membranes were characterized by SEM, XRD and FT-IR. A study of the proton conductivity as a function of the composite membranes was carried out at 90 °C and 95% RH. Referencias [1] Y. Gao, R. Broersen, W. Hageman, N. Yan, M. C. Mittelmeijer-Hazeleger, G. Rothenberg, S. Tanase. J. Mater. Chem. A, 2015, 3, 22347–22352. [2] A. Cabeza, P. Olivera-Pastor, R. M. P. Colodrero. Tailored Organic-Inorganic Materials, Brunet, E., Colón, J.L., Clearfield, A., Eds.; John Wiley & Sons, Inc. 2015; Ch. 4, 137−191.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech