Yazar "Sahin, E" seçeneğine göre listele

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    Both anodically and cathodically coloring electrochromic polymer based on dithieno[3,4-b,3?,4?-e]-[1,4]-dithiine
    (Elsevier Science Sa, 2006) Sahin, E; Camurlu, P; Toppare, L
    In this study poly(dithieno[3,4-b,3',4'-e]-[1,4]-dithiine) (PDTH) was synthesized potentiodynamically in both p- and n-doping domains in 0.1 M tetrabutylammonium tetrafluoroborate/acetonitrie/borontrifluoride ethylether (8:2, v/v). Resulting homopolymer was characterized via cyclic voltammetry, FTIR and UV-vis Spectroscopy. PDTH revealed both anodically and cathodically coloring electrochromic behavior, upon p-and n-doping, respectively. Spectroelectrochemistry analysis of p-doped polymer, reflected electronic transitions at 450-486, 766 and similar to 900nm, revealing pi-pi degrees transition, polaron and bipolaron band formation, respectively. As an anodically coloring material, polymer revealed multi-color electrochromism, exhibiting brick, green and light gray colors. As the cathodically coloring material, color varied between highly transmissive and brown, as such this material exhibits potential controllable states. Switching ability of the polymer was also investigated by a kinetic study upon measuring the %T at the maximum contrast point. Results showed that PDTH is a potential material for electrochromic devices both as anodically and cathodically coloring material. (c) 2005 Elsevier B.V All rights reserved.
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    Conducting copolymers of thiophene functionalized polystyrenes with thiophene
    (Elsevier Science Sa, 2005) Sahin, E; Camurlu, P; Toppare, L; Mercore, VM; Cianga, I; Yagci, Y
    Thiophene capped polystyrenes (TCP1, TCP2) were synthesized by atom transfer radical polymerization of styrene followed by Suzuki condensation with 2-thiophene boronic acid. Electrically conducting graft polymers of TCP1 and TCP2 with thiophene were achieved by electrochemical methods. Characterization of the graft polymers were performed by cyclic voltammetry (CV), Fourier transform infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy analyses. Electrochromic properties of the conducting copolymers were investigated by spectroelectrochemistry, kinetic and colorimetry studies. The observed lambda(max) and band gap values were found to be at 432 nm, 2.10 eV and 453 nm, 2.13 eV for P(TCP1 -co-Th) and P(TCP2-co-Th), respectively. Also, we successfully established the utilization of dual-type complementary colored polymer electrochromic devices using P(TCP I co-Th)/poly(3,4-ethylenedioxythiophene) (PEDOT) in sandwich configuration. The switching ability, stability and optical memory of the electrochromic device were investigated with UV-Vis spectrophotometer and CV. P(TCP1-co-Th)/PEDOT switches between blue and brown. (c) 2005 Elsevier B.V. All rights reserved.
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    Determination of stability constants and thermodynamic parameters of some metal complexes with 2-hydroxynaphthalene-1-carbaldehydene-1-naphthylamine
    (Maik Nauka/Interperiodica/Springer, 2005) Ziyadanogullari, B; Aydin, F; Sahin, E; Aydin, I; Temel, H
    The thermodynamic parameters of complexes of Cu(II), Ni(II), and Zn(II) cations with hydroxynaphthalene-1-carbaldehydene-1-naphthylamine were determined in 60% (v/v) DMF-water, at various ionic strengths (0.07, 0.13, 0.2 M NaNO3), and at different temperatures (25, 30, 35, 40 +/- 0.1 degrees C) using a spectrophotometric method. A sodium nitrate solution was used to maintain the ionic strengths. The stability constants show an inverse relationship with the ionic strengths. The thermodynamic parameters (60% (v/v) DMF-water (Delta G(0), Delta H-0, Delta S-0)) based on these formation constants were determined. The acid dissociation constant of the ligand was investigated in 60% (v/v) DMF-water and was also calculated at different temperatures.
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    The enantiomeric recognition of chiral organic ammonium salts by chiral monoaza-15-crown-5 ether derivatives
    (Pergamon-Elsevier Science Ltd, 2004) Turgut, Y; Sahin, E; Togrul, M; Hosgören, H
    Novel chiral monoaza-15-crown-5 ether derivatives 1 and 2 were prepared frorn L-phenylalaninol and L-leucinol, respectively. The effect of the substituent at the stereogenic center on chiral recognition and enantioselectivity were investigated. Binding constant (K), free-energy changes (-DeltaG(0)), enthalpy change (DeltaH), and entropy change (DeltaS) values were determined with enantiomers of organic ammonium salts by a titration UV-vis method in CHCl3. (C) 2004 Elsevier Ltd. All rights reserved.
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    Interpretation of sorption kinetics for mixtures of reactive dyes on wool
    (Tubitak Scientific & Technological Research Council Turkey, 2005) Sahin, E
    The equilibrium sorption isotherms of 3 reactive dyes (C. I. Reactive Yellow 84, C. I. Reactive Red 141, C. I. Reactive Blue 160) and their binary mixtures adsorbed on prewetted wool fiber were investigated. The kinetic studies were carried out at pH <= 7 and 80 degrees C in dye solutions containing 20 g/L NaCl. It was reported that binary mixtures of these reactive dyes have lower sorption values than the dyes alone, at the same dye concentration, pH and temperature. The isotherms obtained are Langmuir type. The rate parameters of adsorption kinetics decrease with increasing dye concentration.
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    The removal of dyes from water by modified bentonite
    (Parlar Scientific Publications (P S P), 2004) Aydin, AH; Sahin, E; Akçay, G
    Colour removal is an important task in textile waste-water treatment. Dodecylammonium bentonite (DOB) was used as sorbent for reactive blue 160 (RB), reactive yellow 84 (RY), direct blue 71 (DB), and direct yellow 50 (DY). Langmuir and Freundlich sorption parameters were calculated and the adsorption data fitted well to the Langmuir isotherm. The monolayer adsorption capacity of DOB increases and follows the orders RB>RY>DB>DY and DB>RB> RY> DY for the dyes at 298 K and 308 K, respectively. The thermodynamical equilibrium constant (KO), standard free energy (DeltaG(0)), enthalpy (DeltaH(0)) and entropy (DeltaS(0)) changes have been also calculated to predict the nature of adsorption.
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    Synthesis, characterization and electrochromic properties of a conducting copolymer of pyrrole functionalized polystyrene with pyrrole
    (Elsevier Sci Ltd, 2006) Tarkuc, S; Sahin, E; Toppare, L; Colak, D; Cianga, I; Yagci, Y
    A well-defined polystyrene (PSt) based polymer containing at one end-chain 3.5-dibromobenzene moiety. prepared by atom transfer radical polymerization (ATRP), was modified in two reaction steps. First one constitutes a Suzuki coupling reaction between aromatic dibromine functional polymer and 3-aminophenylboronic acid, when a diamino-containing intermediate was obtained. The second step is a condensation reaction between the diamino functional polystyrene and 2-pyrrole alclehyde. Thus, a polymer containing a conjugated sequence having pyrollyl groups at the extremities was synthesized. The presence of oxidable pyrrole groups in the structure of the polymer permitted further electropolymerization. The structures of intermediate polymers were analyzed by spectral methods (H-1 NMR, FTIR). Electrochemical copolymerization of pyrrole functionalized polymer (PStPy) with pyrrole was carried out in acetonitrile (ACN)-tetrabutylammonium tetrafluoroborate (TBAFB) solvent electrolyte Couple. Characterization of the resulting copolymer were performed via Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC). scanning electron microscopy (SEM), spectroclectrochemical analysis, and kinetic study. Spectroelectrochemical analysis show that the copolymer of PStPy with Py has an electronic band gap (due to pi-pi* transition) of 2.4 eV at 393 nm, with a yellow color in the fully reduced form and a blue color in the fully oxidized form. Via kinetic studies. the optical contrast %Delta T was found to be 20% for P(PStPy-co-Py). Results showed that the time required to reach 95% of the ultimate T was 1.7 s for the P(PStPy-co-Py). (c) 2006 Elsevier Ltd. All rights reserved.
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    Synthesis, characterization and electrochromic properties of copolymer of terephthalic acid bis-(thiophen-3-yl-methyl) thioester with thiophene
    (Taylor & Francis Inc, 2006) Turkarslan, O; Erden, A; Sahin, E; Toppare, L
    Terephthalic acid bis-(thiophen-3-yl-methyl thioester) (TTMT) was synthesized via the reaction of thiophen-3-yl methanethiol with terephthaloyl dichloride. Nuclear magnetic resonance ( H-1-NMR) spectroscopy and Fourier transform infrared (FTIR) spectroscopy were utilized for the characterization of the monomer. Electrochemical copolymerization of TTMT with thiophene in acetonitrile/boron trifluoride diethyl etherate (AN/BFEE) (8:2, v/v) solvent mixture was realized by using tetrabutylammonium tetrafluoroborate (TBAFB) as the supporting electrolyte. The resulting copolymer was characterized via cyclic voltammetry (CV), FTIR, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), four-probe technique conductivity measurement and UV-Vis spectroscopy. Spectroelectrochemical analysis of the copolymer, P(TTMT-co-Th), reflected pi to pi* transition at 476 nm and band gap was calculated as 2.03 eV. Kinetic studies were carried out upon measuring the percent transmittance (%T=16%) at the maximum contrast point and switching time (1.25 s). A dual type electrochromic device (ECD) of P(TTMT-co-Th) and poly(3,4-ethylenedioxythiophene) (PEDOT) was constructed. Spectroelectrochemistry, switching ability, open circuit memory and stability of the device were examined by UV-Vis spectroscopy and cyclic voltammetry. The device switches between brown and blue, exhibits 0.0 V and 2.6 V as the switching voltages and short switching time (1.03 s).