Synthesis and characterization of new fluorinated copolymers based on azole groups for fuel cell membranes

International audienceTwo new fluorinated copolymers synthesized by grafting ω-hydroxyl pyrazolic (Trip) and triazolic (Trit) tripods onto poly(chlorotrifluoroethylene-alt-2-iodoethyl vinyl ether) copolymer (poly(CTFE-alt-IEVE) are reported.These copolymers were prepared in two steps: the ω-hydroxy nitrogenous heterocycles reacted with iodine atomsof poly(CTFE-alt-IEVE) copolymer followed by the deprotection of the benzyl group. The chemical structuresof tripod monomers and resulting copolymers were characterized by nuclear magnetic resonance and infraredspectroscopies, elemental analysis, and mass spectrometry. The first analysis allowed one to determine the degreeof grafting that reached 80 and 19% for copolymers bearing pyrazole and triazole, respectively. Membraneswere processed in pellet form by compressing these copolymers. Thermal properties of the membranes,examined by thermogravimetric analysis and differential scanning calorimetry, showed that such copolymerswere thermally stable up to 200°C under air, and exhibited glass transition temperatures ranging between 31and 47°C. The temperature dependence of conductivity led to a simple Arrhenius behavior for both copolymers.Poly(CTFE-alt-IEVE)-dep-Trit⁠19% and poly(CTFE-alt-IEVE)-dep-Trip⁠80% copolymers had a maximum protonconductivity of 1.3 10⁠−3 and 5.91 10⁠−5mS/cm respectively at 180°C under quasi-anhydrous conditions. CyclicVoltammetry (CV) study illustrated that the electrochemical stability

Fluorinated polymers based on pyrazole groups for fuel cellmembranes

International audienceThe synthesis and characterization of two fluorinated copolymers bearing pyrazole group as precursor of proton-conducting membranes in polymer electrolyte fuel cells are described. 1-Benzyl-5-methyl-3-hydroxymethyl-pyrazole was first synthesized in a two step-reaction. It was then grafted onto poly(chlorotrifluoroethylene -alt-2-iodoethyl vinyl ether) copolymer (poly(CTFE-alt-IEVE)). The degree of grafting was controlled by the reaction time, and reached 30 and 55% after 24 and 48 hours, respectively. Deprotection of the benzyl group produced poly(CTFE-alt-IEVE)-dep-pyrazoley% copolymers. NMR spectroscopy enabled to monitor all reaction steps and ensured the purity of these functional fluorinated copolymers. The poly(CTFE-alt-IEVE)-dep-pyrazoley% copolymers were thermally stable (up to 200 °C under air) and showed a maximum proton conductivity of 4×10-5 mS.cm-1 at 180 °C under anhydrous conditions. From cyclic voltammetry (CV), these copolymers displayed an electrochemical stability domain extended over 2.0 V

Synthesis, characterization, X-ray structure and in vitro antifungal activity of triphenyltin complexes based on pyrazole dicarboxylic acid derivatives

International audienceA series of new ditriphenyltin(IV) dicarboxylate complexes of general formula (Ph3SnOOC-Pz)2R with Pz: pyrazole and R: alkyl or ether, have been synthesized from bipyrazoledicarboxylic acid and hydroxytripheyltin. These complexes, noted C1-C7, have been characterized by IR, 1 H and 13 C NMR spectroscopies. The molecular structures of C3: 1,3-Bis[(5-methyl-2-H-3-triphenyltincarboxylate pyrazol)]propane and C7: Bis[(2-methyl-2H-3triphenyltincarboxylate pyrazol)ethyl]oxide have been confirmed by single crystal X-ray diffraction. Both compounds crystallize in the monoclinic symmetry: C3 in P21 space group with a = 15.915(1) Å, b = 10.0791(8) Å, c = 13.823(1) Å, α = 90°, β = 100.459(3)°, γ = 90° and C7 in P21/n space group, with a = 15.0951(7) Å, b = 8.9847(3) Å, c = 34.244(1) Å, α = 90°, β = 101.421(2)°, γ = 90°.. The two cristallographically independent Sn1 and Sn2 atoms are tetra coordinated within distorted tetrahedral environments, very similar in the two compounds. The antifungal activity of these organotin complexes and their corresponding bipyrazoledicarboxylic acid (ligands) has been evaluated against the pathogenic Fusarium oxysporum f. sp. albedinis. This activity greatly depends on the nature of ligands and on the dose used. The presence of triphenyltin moiety improves considerably the antifungal activity becoming close to that of the benomyl (fungicide)

Hartree-Fock and density functional theory studies on tautomerism of 5,5o-diisopropyl-3,3o-bipyrazole in gas phase and solution.

International audienc

A NEW C,C-LINKED FUNCTIONALIZED BIPYRAZOLE: SYNTHESIS, CRYSTAL STRUCTURE, SPECTROSCOPIES AND DFT STUDIES. EVALUATION OF THE ANTIBACTERIAL ACTIVITY AND CATALYTIC PROPERTIES

International audienceThe synthesis of new C,C-linked functionalized bipyrazole is reported. Its molecular structure has been confirmed by spectroscopic and spectrometric methods and its single crystal structure determined by X-ray analysis. The ligand 2 has been subjected to DFT and TD-DFT theoretical calculations and results are consistent with the experimental chemical analyses. The compound possesses no antibacterial activity up to 256 g/mL. However, its complexes with copper(II) salts are found to be good catalysts for the oxidation of 3,5-di-tert-butylcatechol (DTBC) into 3,5-di-tert-butylquinone (DTBQ) with a rate varying from 9.58 μmol• L-1• min-1 for the 2-[Cu(MeCO2)2] complex to 5.27 μmol• L-1• min-1 for the 2-[Cu(BF4)2] complex

Synthesis of a Series of Chalcones and Related Flavones and Evaluation of their Antibacterial and Antifungal Activities

International audienc