Preparation and characterization of sulfonated polyimide ionomers via post‐sulfonation method for fuel cell applications

This paper describes our work on the synthesis of a series of sulfonated homo‐/co‐polyimides (SPI) which were obtained by post‐sulfonation method over three steps. In the first step, 4,4′‐oxydianiline (ODA) and 4,4′‐diaminodiphenylsulfone (DDS) dissolved in N‐methyl pyrrolidone (NMP) were reacted with benzophenonetetracarboxylic dianhydride (BTDA) in order to yield poly(amic acid) (PAA). Secondly, precipitated PAA was sulfonated via concentrated sulfuric acid (95–98%) at room temperature to give post‐sulfonated PAA (PSPAA). Finally, PSPAA was converted into post‐sulfonated PI (PSPI) by the thermal imidization method. PSPIs with ion exchange capacity (IEC) ranging from 0.20 to 0.67 meq/g were prepared. The thermal properties of the PSPIs were evaluated and high desulfonation temperature was found in the range of 190–350°C, suggesting the high stability of sulfonic acid groups. In water, PSPI‐5 membrane displayed similar proton conductivity to Nafion®117, whereas this membrane showed poor conductivity in dry state. All PSPIs displayed good solubility in common polar aprotic solvents such as NMP and dimethylacetamide (DMAc). Furthermore, the effects of post‐sulfonation reaction on chemical structure, thermal oxidative behavior, and physical properties of the PSPI membranes such as membrane quality/stability and water uptake were discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Efficient one-pot three-component method for the synthesis of highly fluorescent coumarin-containing 3,5-disubstituted-2,6-dicyanoaniline derivatives under microwave irradiation

A simple and concise approach to the synthesis of coumarin-containing highly fluorescent asymmetric/symmetric 3,5-diaryl/heteroaryl-2,6-dicyanoaniline derivatives are reported. The compounds were synthesized through base catalyzed three-component one-pot synthesis reaction of 2-(1-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)ethylidene)malononitrile, aliphatic, aromatic/heteroaromatic aldehydes, and malononitrile in solvent-free reaction medium, catalyzed by piperidine under microwave irradiation method. The reaction gave the novel, highly fluorescent coumarin-containing 3,5-disubstituted-2,6-dicyanoaniline derivatives in good yields at 300?W, 80?°C in 2?min. This method provides several advantages; such as shorter reaction time, environmental friendliness, simple workup procedure, lower energy consumption and, generally, good yields with high purity. In addition, the synthesized compounds are fluorescently active dyes even in day light, except for compounds including nitro substituent, and show maximum absorption wavelengths (λ_abs.max) in the visible region in DMSO at room temperature. Thermal properties of all the synthesized compounds were also evaluated with thermal gravimetric analysis for usability as optic dye. Optical and thermal screening studies of the compounds showed that the dyes have excellent photophysical and thermal stability properties.     

Study on the stability of supercritical fluid extracted rosemary (<Emphasis Type="Italic">Rosmarinus offcinalis</Emphasis> L.) essential oil

The aim of this study was to examine the influence of storage conditions and duration on composition and antioxidant activity of supercritical fluid (SCF) extracted essential oil of rosemary (Rosmarinus officinalis L.). Supercritical extraction was carried out sequentially by using SCF carbondioxide in the first two steps and with 5% ethanol as entrainer in the third step. The compositions of the extracts were determined by gas chromatography/mass spectrometry. The total phenolics were analyzed using Folin-Ciocalteau assay. Antioxidant activities of the extracts were tested by β-carotene-linoleic acid bleaching method.     

Structural properties of trans‐cyclohexane‐1,2‐diamine complexes of copper(II) and zinc(II) acesulfamates

The title compounds, trans‐bis(trans‐cyclohexane‐1,2‐diamine)bis(6‐methyl‐2,2,4‐trioxo‐3,4‐dihydro‐1,2,3‐oxathiazin‐3‐ido)copper(II), [Cu(C₄H₄NO₄S)₂(C₆H₁₄N₂)₂], (I), and trans‐diaquabis(cyclohexane‐1,2‐diamine)zinc(II) 6‐methyl‐2,2,4‐trioxo‐3,4‐dihydro‐1,2,3‐oxathiazin‐3‐ide dihydrate, [Zn(C₆H₁₄N₂)₂(H₂O)₂](C₄H₄NO₄S)₂·2H₂O, (II), are two‐dimensional hydrogen‐bonded supramolecular complexes. In (I), the Cu^II ion resides on a centre of symmetry in a neutral complex, in a tetragonally distorted octahedral coordination environment comprising four amine N atoms from cyclohexane‐1,2‐diamine ligands and two N atoms of two acesulfamate ligands. Intermolecular N—H...O and C—H...O hydrogen bonds produce R₂²(12) motif rings which lead to two‐dimensional polymeric networks. In contrast, the Zn^II ion in (II) resides on a centre of symmetry in a complex dication with a less distorted octahedral coordination environment comprising four amine N atoms from cyclohexane‐1,2‐diamine ligands and two O atoms from aqua ligands. In (II), an extensive two‐dimensional network of N—H...O, O—H...O and C—H...O hydrogen bonds includes R₂¹(6) and R₄⁴(16) motif rings.     

Synthesis and Structural Studies of 6-（2,5-Dimethyl-1H-pyrrol-1-yl）pyridin-2-amine

6-(2,5-Dimethyl-1H-pyrrol-1-yl)pyridin-2-amine (1) was synthesized and characte-rized by elemental analyses,1H-NMR and 13C-NMR,FTIR,Uv-Vis,mass spectral studies and single-crystal X-ray diffraction.All data obtained from spectral studies support the structural properties of 1.Intermolecular N-H…N hydrogen bonds produce an R22(8) ring.An extensive three-dimensional network formed by C-H…π and N-H…π-facial hydrogen bonds is responsible for the crystal stabilization.The combination of C-H…π interactions produces R33(12),R43(19) and R44(20) rings.     

Outstanding spin-orbit-activated interchannel coupling in the Cs and Ba 3d photoemission

Partial 3d5/2 photoionization cross sections of atomic Cs and Ba as well as the asymmetry parameter beta of the angular distribution of the Cs 3d5/2 photoelectrons were investigated near the threshold of the 3d3/2 channel at about 750 eV and 800 eV, respectively. Strong electron correlations, in particular, the spin-orbit activated interchannel coupling between the 3d5/2 and 3d3/2 channels, govern the observed spectra. The most striking effect was found for beta5/2 of Cs with a dramatic increase from beta=1.0 to beta=1.5 in the energy region where the mixing between both channels causes a pronounced minimum in the partial 3d5/2 cross section. This result indicates the decisive influence of the interference term on the asymmetry parameter beta with its dependence on the phase difference between the outgoing p and f waves.     

The synthesis and structural characterization of transition metal coordination complexes of coumarilic acid

The coumarilate (coum^?) complexes of Co^II(1), Ni^II(2) Cu^II(3) and Zn^II(4) were synthesized and characterized by elemental analysis, magnetic susceptibility, solid-state UV–Vis, FTIR spectra, thermoanalytical TG–DTG/DTA and single-crystal X-ray diffraction methods. It was found that all of the complex structures have 2 mol (coum^?) ligand bonded as monoanionic monodentate in the structures of 1 and 2 while they were coordinated to metal cations as monoanionic bidentate in the complexes 3 and 4. There was not any hydrate water in the metal complexes. The complexes of 1 and 2 have four moles of aqua ligand, and the other complexes have two moles. Thermal decomposition of each complex starts with dehydration, and then the decomposition of organic parts goes. The thermal dehydration of the complexes takes place in one (for the compounds of 2, 3, 4) or two (for the compound 1) steps. The decomposition mechanism and the thermal stability of the complexes under investigation were determined on the basis of their structures. Metal oxides were obtained as the final decomposition product.     

On constructing total orders and solving vector optimization problems with total orders

In this paper, we introduce a construction method of total ordering cone on \mathbbRⁿ{\mathbb{R}^n} . It is shown that any total ordering cone on \mathbbRⁿ{\mathbb{R}^n} is isomorphic to the cone \mathbbRⁿ_lex{\mathbb{R}^n_{lex}} . Existence of a total ordering cone that contain given cone with a compact base is shown. By using this cone, a solving method of vector and set valued optimization problems is presented.     

The synthesis and characterization of copper(II)–<Emphasis Type="Italic">p</Emphasis>-aminosalicylate complexes with diamine ligands

The complexes were synthesized by the reaction between sodium salt of p-aminosalicylic acid (PAS) and Cu(II) for 1 and corresponding ethylenediamine (en) or its derivatives for 2–6. The complexes were characterized by using elemental analyses, FT-IR, UV–Vis, magnetic moment measurements, and thermal analyses techniques. In complex 1[Cu₂(PA)₄(H₂O)₂], two Cu(II) ions were found as bridged by four μ-O:O′ p-aminosalicylato (PA) ligands, forming a cage structure, and two aqua ligands to form dinuclear square-pyramidal geometry around Cu(II) ions. In the complexes 2–6, the PA (anionic form of p-aminosalicylic acid) coordinated to Cu(II) ions as monodentate manner by using its oxygen atom of deprotonated carboxylic acid and ethylenediamine derivatives coordinated to the Cu(II) ions in bidentate manner to form mononuclear octahedral complexes [Cu(PA)₂(L)₂] (L = ethylendiamine, N,N-dimethylethylendiamine, N,N′-dimethylethylendiamine, N,N,N′,N′-tetramethylethylendiamine, and 1,3-propanediamine, for complexes 2, 3, 4, 5, and 6, respectively). In all the complexes OH and NH₂ groups of PA ligands were not coordinated to metals.     

Secondary metabolites from the roots of Paronychia chionaea

Two novel secondary metabolites, compounds (1-2) were isolated from the roots of Paronychia chionaea. On the basis of spectroscopic data including 1D and 2D NMR experiments (COSY, TOCSY, HSQC, and HMBC), and mass spectroscopy, their structures were established as 6-C-[alpha-L-arabinopyranosyl-( 1 --> 2)-beta-D-glucopyranosyl]-7-O-[beta-D-glucopyranosyl]-luteolin 3'-methyl ether (1), and 2-(methoxy)-2-(3,5-dimethoxy 4-hydroxyphenyl)-ethane-1,2-diol 1-O-beta-D-glucopyranoside (2).