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    A new conducting polymer of 2,5-bis(2-thienyl)-1H-(pyrrole) (SNS) containing carbazole subunit: Electrochemical, optical and electrochromic properties
    (Elsevier Science Sa, 2009) Koyuncu, Sermet; Zafer, Ceylan; Sefer, Emre; Baycan Koyuncu, Fatma; Demiç, Şerafettin; Kaya, İsmet; Özdemir, Eyüp
    We report here the synthesis of a new electroactive monomer 3,6-di-tert-butyl-[4-(2,5-di-2-thienyl-1H-pyrrol-1-yl)phenyl]-9H-carbazole in five steps and polymerization of this monomer by two different procceses: Kumada Coupling and electro-oxidative. The product obtained by chemical polymerization exhibits a high thermal stability and narrow molecular weight distribution. While, in the UV-vis absorption spectrum of monomer the absorption peaks appear at 338 nm, the chemically synthesized polymer absorbs at 428 nm with 90 nm red shift. Cyclic voltammogram of monomer shows two separate oxidation processes which reflect the first oxidation at +0.84 V and a second one at +1.43 V. When the polymeric film prepared by electrochemical process was subjected to a repeated cyclic scan between -0.2V and +1.0V, it switches among three different colors (orange, green and blue). The oxidation and reduction response times were calculated as 2.0 s for this polymer film and exhibits high redox stability. The results anticipate that this kind of polymers can be used for designing electrochromics based on the use of one molecule for the generation of three basic colors (RGB). (C) 2009 Elsevier B.V. All rights reserved.
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    Electrochemical and optical properties of novel donor-acceptor thiophene-perylene-thiophene polymers
    (Wiley, 2008) Koyuncu, Sermet; Kuş, Mahmut; Demiç, Şerafettin; Kaya, İsmet; Özdemir, Eyüp; İçli, Sıddık
    In this study, donor-acceptor type thiophene-perylene-thiophene monomers were synthesized and polymerized by both oxidative polymerization using FeCl3 as catalyst and the electrochemical process. UV-vis, FTIR, H-1 NMR, and elemental analysis techniques were used for structural characterization. Thermal behaviors of these compounds were determined by using TGA system. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels and electrochemical and optical band gap values were calculated by using the results of cyclic voltammetry and UV-vis measurements, respectively. The number-average molecular weight (M-n), weight-average molecular weight (M-n), and polydispersity index (PDI) values of synthesized polymers were determined by size exclusion chromatography. Conductivity measurements of these polymers were carried out by electrometer by using a four-point probe technique. The conductivity was observed to be increased by iodine doping. (C) 2008 Wiley Periodicals, Inc.