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Article Citation - WoS: 14Citation - Scopus: 17NEW EDOT CONTAINING POLYMERS: EFFECT OF RING SIZE ON THE BENZIMIDAZOLE ACCEPTOR(Pergamon-elsevier Science Ltd, 2016) Cansu-Ergun, E. G.; Onal, A. M.; Cihaner, A.In this study, three different benzimidazole (BIm) based acceptor groups bearing cyclohexane, cycloheptane and cyclooctane rings at 2-C position of benzimidazole were synthesized and coupled with ethylenedioxythiophene (EDOT) donor units via Stille cross-coupling reaction. The resulting donor acceptor-donor (DAD) type monomers were examined in terms of their electrochemical and optical behaviors. All three monomers exhibited dual absorption bands due to their donor-acceptor pattern and exhibited one irreversible oxidation peak at about 0.80 V. The monomers were electrochemically polymerized via both potentiostatic and potentiodynamic methods and electro-optical properties of obtained conjugated polymer films were investigated in monomer free electrolytic solution. It was found that the polymer films exhibited quasi-reversible redox behavior due to the doping/dedoping process of the polymers, which was accompanied by a reversible electrochromic behavior. Electrochromic investigations showed that all three polymer films showed similar multichromic behaviors: green in the neutral state, gray in the oxidized state, and brick-red in the reduced state. Their band gap (Eg) values were elucidated utilizing spectroelectrochemical data and it was found to be around 1.18 eV. Furthermore, one of the polymer film was utilized for the construction of transmissive type electrochromic device (ECD) with poly(3,4-ethylenedioxythiophene) (PEDOT). (C) 2015 Elsevier Ltd. All rights reserved.Article Citation - WoS: 9Citation - Scopus: 10Effect of Ring Size on Benzimidazole Unit on Electro-Optical Properties of Donor-Acceptor Type Monomers and Their Polymers(Elsevier Science Sa, 2016) Al-Ogaidi, Saad; Karabay, Bads; Karabay, Lutfiye Canan; Cihaner, AtillaA new series of fluorescent donor-acceptor-donor (D-A-D) type monomers based on benzimidazole acceptor unit bearing various cycloalkane appendages, called 4,7-di-2,3-dihydrothieno[3,4-b] [1,4]dioxin-5-ylspiro[benzimidazole-2,1'-cyclopentane] (E5E), 4,7-di-2,3-dihydrothieno[3,4-b] [1,4]dioxin-5-ylspiro[benzimidazole-2,1'-cyclohexane] (E6E) and 4,7-di-2-thienylspiro[benzimidazole-2,1'-cyclohexane] (T6T), were synthesized and polymerized via potentiostatic and potentiodynamic methods. The effect of ring size on benzimidazole unit and the kind of donor moiety in D-A-D system on the electrochemical and optical properties have been studied systematically. The optical studies showed that the ring size of the benzimidazole unit has no effect on the absorbance and fluorescence properties, whereas the oxidation potential of the E5E, E6E and T6T monomers varied with respect to both the ring size and the kind of donor unit: 0.89 V, 0.83 V and 122 V vs Ag/AgCl, respectively. All polymers have ambipolar (p- and n-type doping) and electrochromic properties. While the polymer films PE5E and PE6E are green at neutral state and transparent at oxidized state, the polymer PT6T has no appreciable color change between its neutral and oxidized states. The polymers PE5E and PE6E bearing 3,4-ethylenedioxythiophene unit as donor units exhibited lower band gap values (1.21 eV and 1.18 eV, respectively) than the polymer PT6T (1.53 eV). When compared to PT6T, PE5E and PE6E polymers are more stable under ambient condition. While PE5E retained 76% of its electroactivity after 4000 cycles, PE6E has 65% of its electroactivity after 2000 cycles. (C) 2016 Elsevier B.V. All rights reserved.
