Browsing by Author "Karabay, Bads"

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Citation - WoS: 16
Citation - Scopus: 17
Effect of Furan, Thiophene and Selenophene Donor Groups on Benzoselenadiazole Based Donor-Acceptor Systems
(Elsevier Science Sa, 2016) Karabay, Lutfiye Canan; Karabay, Bads; Karakoy, Merve Serife; Cihaner, Atilla; Chemical Engineering
A series of the monomers called 4,7-di(furan-2-yl)benzo[c][1,2,5]selenadiazole (OSeO), 4,7-di(thiophen-2-yl)benzo[c]11,2,5]selenadiazole (SSeS) and 4,7-di(selenophen-2-yl)benzo[c][1,2,5]selenadiazole (SeSeSe) was synthesized via a donor-acceptor-donor (D-A-D) approach. Benzoselenadiazole was used as an acceptor unit and furan, thiophene and selenophene were used as donor units. The effects of chalcogen atoms (0, S, and Se) in furan, thiophene and selenophene were investigated systematically on the properties of the monomers and their corresponding polymers (POSeO, PSSeS and PSeSeSe, respectively), which were polymerized electrochemically via potentiodynamic or potentiostatic methods. The monomers OSeO, SSeS and SeSeSe exhibited low oxidation potentials of 1.15, 1.25 and 1.19 V vs. Ag/AgCl, respectively. Intramolecular charge transfer interaction between donor and acceptor units was demonstrated from the emission spectra of the monomers. Also, the optical studies showed that the ambipolar and electrochromic polymers POSeO, PSSeS and PSeSeSe have low band gaps of 1.57, 1.47 and 1.45 eV, respectively. (C) 2016 Elsevier B.V. All rights reserved.
Citation - WoS: 8
Citation - Scopus: 9
Effect 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, Atilla; Chemical Engineering
A 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.
Citation - WoS: 2
Citation - Scopus: 2
New electrochromic copolymers based on spiro bipropylenedioxythiophene and 3,4-ethylenedioxythiophene
(Elsevier Science Sa, 2014) Pekel, Lutfiye Canan; Karabay, Bads; Cihaner, Atilla; Chemical Engineering
Two alkylenedioxythiophene derivatives, Spiro bipropylenedioxythiophene (Spiro-BiProDOT) and 3,4-ethylenedioxythiophene (EDOT), were integrated electrochemically in order to attain low band gap electrochromic copolymers. EDOT has a functionality of two, which causes a linear polymer, whereas Spiro-BiProDOT has a functionality of four and its polymerization results in a network polymer. Therefore, by playing the monomer feed ratio, the crosslink degree can be adjusted for the copolymers obtained electrochemically from EDOT and Spiro-BiProDOT monomers in an electrolyte solution of 0.1 M tetrabutyl ammonium hexafluorophosphate dissolved in dichloromethane. It was found that copolymers showed different electrochemical and optical properties at their various redox states when compared to their homopolymers. For example, they could be switched from dark blue in the neutral state to reddish blue at intermediate state and finally to transparent blue in the oxidized state with 45-51% of the transmittance change at 575-595 nm. pi-pi* transition bands of the copolymers can be shifted to higher wavelengths when compared to poly(Spiro-BiProDOT) by increasing the amount of the EDOT units in the polymer backbone. They have low band gaps in the range of 1.65 and 1.73 eV. (C) 2014 Elsevier B.V. All rights reserved.