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Atilim University,

Chemical Engineering and Applied Chemistry, ATOMSEL

Incek, Golbasi, 06836
Ankara-Turkey
Phone: +903125868304-8817
Fax: +903125868091
E-mail: cihaner@atilim.edu.tr

25. A New Conducting Polymer Bearing 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) Subunit: Synthesis and Characterization

Atilla Cihaner and Fatih Algi
Electrochimica Acta, 54, 786-792 (2008)

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A new monomer system based on thiophene, pyrrole and 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene dye (SNS-BODIPY)was synthesized and its corresponding polymer (PSNS-BODIPY) was obtained via repetitive cycling or constant potential electrolysis in 0.1M tetrabutylammonium hexafluorophosphate dissolved in dichloromethane. The PSNS-BODIPY film has very stable and well-defined reversible redox couples during p-doping process. Multi-electrochromic polymer film has a band gap of 2.9 eV with two absorption bands in its neutral state at 351 and 525 nm, attributed to the polymer backbone and BODIPY subunits, respectively. The percentage transmittance changes between both states (neutral and oxidized) were found as 12.1 % for 351 nm and 17.7 % for 525 nm in the visible region as well as 46.2 % for 1050nm in the near-infrared region. Beyond the robustness, the PSNS-BODIPY film has high redox stability (retaining 53.3 % of its electroactivity at 351 nm after 2000 switching) with a low response time of 1.0 s.

 
24. Electrochemical Polymerization of 9-fluorenecarboxylic Acid and Its Electrochromic Device Application

Buket Bezgin, Atilla Cihaner and Ahmet M. Önal
Thin Solid Films, 516, 7329-7334 (2008)

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Poly(9-fluorenecarboxylic acid) (PFCA) was synthesized by electrochemical oxidation of 9-fluorenecarboxylic acid (FCA) using a mixture of nitromethane and boron trifluoride diethyl etherate as the solvent and tetrabutylammonium tetrafluoroborate as the supporting electrolyte. An insoluble and conducting brownish-orange film was deposited on the electrode surface, both during repetitive cycling and constant potential electrolysis at 1.15 V. Characterization of the polymer film has been carried out using Fourier Transform Infrared spectroscopy technique and thermal behavior was studied via thermal gravimetric analysis. Structural analysis showed that the polymerization of FCA occurred at 2,7- position. Spectroelectrochemical behavior of the polymer film on indium tin oxide working electrode was studied by recording the electronic absorption spectra, in-situ, in monomer-free electrolytic solution at different potentials and it is found that the PFCA film can be reversibly cycled between 0.0 V and 1.2 V. Furthermore, a dual type electrochromic device based on PFCA was constructed and its spectroelectrochemical properties were investigated. The electrochromic device exhibits color change from transparent to dark blue with a good open circuit memory.

 
23. Impedance Spectroscopy of N-Substituted Oligo-Oxyethylene Polypyrrole Films

Atilla Cihaner and Ahmet M. Önal
Journal of Applied Polymer Science, 108, 2373-2378 (2008)

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The electrochemical properties of neutral (dedoped) and oxidized (doped) poly(1,11-bis(1,1-pyrrole)- 3,6,9-trioxaundecane) (poly-I) film electrodes were investigated using cyclic voltammetry and electrochemical impedance spectroscopy (EIS) techniques. Poly-I was deposited on glassy carbon electrode (GCE) from acetonitrile solution containing 5.0 3 1023 M 1,11-bis(1,1-pyrrole)-3,6,9-trioxaundecane (I) and 0.1M LiClO4 supporting electrolyte. Doped poly-I exhibits a single semicircle in its complex-capacitance plots, indicating a single dominant ion transport process, together with high capacitance values. These features make this polymer film a candidate for an energy storage material. Also, poly-I can be a candidate as a sensory material for the detection of Ag1 based on impedance parameters.

 
22. Synthesis of N-Polyethereal Polypyrroles and Their Application for the Preconcentration of Rare Earth Ions

Bahar Köksel, Atilla Cihaner, Murat Kaya, Mürvet Volkan and Ahmet M. Önal
Journal of Applied Polymer Science, 108, 2707-2711 (2008)

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Conducting polymers containing polyether pseudocages (PI, PII, PIII) have been synthesized via chemical oxidation of 1,5-bis(1,1-pyrrole)-3-oxabutane (MI), 1,8- bis(1,1-pyrrole)-3,6-dioxahexane (MII), and 1,11-bis(1,1-pyrrole)- 3,6,9-trioxaundecane (MIII) using anhydrous FeCl3 in CHCl3. Because as obtained polymer resins did not give any response toward any cations, they were reduced (undoped) using chemical reducing agents. Tetrabutylammonium hydroxide was found to be more effective in undoping to obtain more reproducible and reusable polymer resins. The undoped polymer resins were tried in the extraction of rare earth metal ions from the aqueous medium. Among them, only PIII resin removes La(III), Eu(III) and Yb(III) and can be employed for the preconcentration of these metal ions. For batch extraction of La(III), Eu(III) and Yb(III) at neutral pH values, percent recoveries of 98.0 %, 90.7%, 87.3%, respectively, has been obtained. The sorption capacity is found as 1.3 mg of La(III) per gram of PIII resin. The PIII resin could be reused at least five times without significant change in its sorption capacity.

 
21. An Electrochromic and Fluorescent Polymer Based on 1-(1-naphthyl)-2,5-di-2-thienyl-1H-pyrrole

Atilla Cihaner and Fatih Algi
Journal of Electroanalytical Chemistry, 614, 101-106 (2008)

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A novel polymer was synthesized by electrochemical polymerization of 1-(1-naphthyl)-2,5-di-2-thienyl-1H-pyrrole (SNS-1-NAPH). The corresponding polymer (PSNS-1-NAPH) was characterized by cyclic voltammetry, FT-IR and UV–vis spectroscopy. The polymer has a very well-defined and reversible redox process in both organic and aqueous solutions. Furthermore, it shows stable electrochromic behavior; yellow in the neutral state, green in the intermediate state and violet in the oxidized state. PSNS-1-NAPH is soluble in common solvents. Although SNS-1-NAPH is almost nonfluorescent, its polymer is a yellow and/or green light emitter.

 
20. An Electroactive Polymeric Material and Its Voltammetric Response Towards Alkali Metal Cations in Neat Water

Fatih Algi and Atilla Cihaner
Tetrahedron Letters, 49, 3530-3533 (2008)

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The syntheses and characterization of a unique system based on thiophene, pyrrole and benzo-15-crown-5 (SNS-Crown) and its corresponding polymer (PSNS-Crown) are reported. Furthermore, selective, clear and reversible voltammetric responses of the conjugated polymer (PSNS-Crown) film towards the alkali series Li+, Na+ and K+ in both neat water and organic media (ethanol) are described.

 
19. A Novel Conducting Polymer Based on Terthienyl System Bearing Strong Electron-Withdrawing Substituents and Its Electrochromic Device Application

Demet Asil, Atilla Cihaner, Fatih Algi and Ahmet M. Önal
Journal of Electroanalytical Chemistry, 618, 87-93 (2008)

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A novel conducting polymer bearing strong electron-withdrawing substituents (EWS) directly attached to the 3,4-positions of the thiophene ring was synthesized by electrochemical polymerization of diethyl 2,5-di(thiophen-2-yl)thiophene-3,4-dicarboxylate (SSS-Diester). The polymer (PSSS-Diester) was characterized by cyclic voltammetry, FT-IR and UV–vis spectroscopy. The polymer has a reversible redox process and demonstrates a stable electrochromic behavior; reddish orange in the neutral state, brown in the intermediate state and green in the oxidized state. Optical density and response time of the dual-type electrochromic device based on PSSS-Diester were found to be 0.23 and 0.6 s at 623 nm, respectively. It is also noteworthy that the device shows good environmental and redox stability (i.e. 94% of the optical activity of the device retained after 500th switch).

 
18. A Processable Rainbow Mimic Fluorescent Polymer and Its Unprecedented Coloration Efficiency in Electrochromic Device

Atilla Cihaner and Fatih Algi
Electrochimica Acta, 53, 2574-2578 (2008)

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A processable rainbow mimic fluorescent polymer (PSNSF) based on 1-(9H-fluoren-2-yl)-2,5-di(thiophen-2-yl)-1H-pyrrole (SNSF) was synthesized via electrochemical polymerization in a mixture of ethanol and CH2Cl2 solution containing 0.1M LiClO4. Characterization was carried out using cyclic voltammetry, UV–vis and FT-IR spectroscopic techniques. Also, an electrochromic device based on PSNSF was studied, which exhibits high coloration efficiency (CE), high redox stability (retaining 98.6 % of its optical activity after 4000th switch) and very low response time (less than 0.5 s).

 
17. Anodic Polymerization of 2,5-Di-(2-thienyl)-furan in Ethanol

Merve Içli, Atilla Cihaner and Ahmet M. Önal
Electrochimica Acta, 52, 8039-8043 (2007)

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Poly(2,5-di-(2-thienyl)-furan) (PSOS)was synthesized via anodic polymerization of 2,5-di-(2-thienyl)-furan (SOS) in ethanol solution containing 0.2M LiClO4 as supporting electrolyte. The electrochemical and spectroelectrochemical properties were investigated using electroanalytical and UV–vis spectroscopic techniques, respectively. The band gap of the polymer film was found as 2.22 eV and the film was successfully switched between black oxidized state and orange neutral state. Fluorescence and electrochemical impedance spectroscopy (EIS) studies were also performed.

 
16. Electrochemical Polymerization and Characterization of Polyether-Substituted Aniline Derivatives

Seha Tirkes, Atilla Cihaner and Ahmet M. Önal
Polymer International, 56, 1040-1044 (2007)

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New compounds consisting of aniline units linked by polyether bridges have been synthesized and their electrochemical polymerization was performed via constant potential electrolysis and cyclic voltammetry in an aqueous solution containing 3.0 molL-1 H2SO4. Chemical polymerization was carried out using (NH4)2S2O8 as oxidizing agent. It was found that both methods gave the same polymer product without any cleavage of the polyether bridge between aniline rings. The polymers were characterized using the Fourier transform infrared spectroscopic technique and the thermal behavior of electrochemically prepared polymers was investigated using thermogravimetric analysis. Spectroelectrochemical properties of the films were investigated using the in situ UV-visible spectroscopic technique.

 
15. Electrochemical Synthesis of New Conducting Copolymers Containing Pseudo-Polyether Cages with Pyrrole

Atilla Cihaner
Journal of Electroanalytical Chemistry, 605, 8-14 (2007)

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Conducting copolymers have been synthesized via electrochemical oxidation of pyrrole (Py) in the presence of monomer 1,11-bis(1, 1-pyrrole)-3,6,9-trioxaundecane (I) in an electrolytic solution containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6) dissolved in acetonitrile. It is observed that reversible redox behavior of poly(I-co-Py)s shifts to more positive potentials with the increasing amount of I in the comonomer mixture, indicating formation of a copolymer. It is also found that increasing the ratio of I in the comonomer mixture decreases the conductivity of the obtained polymer films. The dark electrical conductivity measurements in the temperature range of 300–100 K revealed the extrinsic type of conduction with activation energy values being in the range of 82.3– 16.9 meV.

 
14. Electrochemical synthesis of Poly(3-bromo-4-methoxythiophene) and Its Device Application

Atilla Cihaner and Ahmet M. Önal
Journal of Electroanalytical Chemistry, 601, 68-76 (2007)

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A functionalized thiophene containing both an electron withdrawing and an electron donating group, 3-bromo-4-methoxythiophene (BrMeOTh) was succesfully polymerized in acetonitrile containing 0.1 M tetrabutylammonium tetrafluoroborate (TBABF4) electrolyte via electrochemical oxidation of the corresponding monomer. BrMeOTh exhibits a lower oxidation potential (1.68 V vs Ag/AgCl) than thiophene (2.05 V vs Ag/AgCl). Spectroelectrochemical properties of poly(3-bromo-4-methoxythiophene) (PBrMeOTh) was investigated in situ recording the electronic absorption spectra of the polymer film coated on indium-tin oxide (ITO) at various potentials. The maximum transmittance difference between the oxidized and reduced states was measured as 39.2% and the time required to attain 90 % of the total transmittance difference was found to be 1.2 s. Both cyclic voltammetric and spectroelectrochemical studies showed that the polymer exhibit a lower oxidation potential, a relatively narrow band gap, a stable conducting state and a higher degree of electrochemical reversibility. It is also found that, as synthesized PBrMeOTh films possess a linear structure along the polymer backbone. Moreover, dual type electrochromic device of PBrMeOTh with poly(3,4-diethylenedioxythiohene) (PEDOT) was constructed and its spectroelectrochemical, electrochromic switching and open circuit stability were investigated. Dual electrochromic device showed a good optical contrast and distinctive color changes with the ability of good switching times (1.1 s) under atmospheric pressure.

 
13. Electrochemical Copolymerization of Thiophene Containing Pseudo-Polyether Cages with Pyrrole

Atilla Cihaner and Ahmet M. Önal
Turkish Journal of Chemistry, 30, 629-634 (2006)

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Conducting copolymers were synthesized via the electrochemical oxidation of pyrrole (Py) in the presence of the monomer 1,12-bis(2-thienyl)-2,5,8,11-tetraoxadodecane (I). The presence of monomer I in the electrolytic solution greatly changed the CV behavior of Py during its potensiodynamic polymerization. The electroactivity of poly(I-co-Py) increased with the increasing amount of I in the comonomer mixture. Copolymer films were prepared via constant potential electrolysis in an electrolytic solution containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6) dissolved in acetonitrile. The spectroelectrochemical properties of the films were investigated using UV-VIS spectroscopy.

 
12. Anodic Oxidation of N-Substituted Dipyrrolyl Linked by Polyether Bridge

Atilla Cihaner
Journal of Macromolecular Science, Part A: Pure and Applied Chemistry, 43, 1379-1386 (2006)

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Electroactive polymer containing polyether pseudo-cages has been synthesized by anodic oxidation of 1,11-bis(1,1-pyrrole)-3,6,9-trioxaundecane (I) using acetonitrile (ACN) as solvent and tetrabutylammonium perchlorate (TBAClO4) as supporting electrolyte. Electrochemical behavior of monomer I and its polymer, poly-I, were studied using cyclic voltammetry (CV) and UV-VIS spectroscopic techniques. Also, a doping/dedoping study was carried out using electron spin resonance (ESR) and UV-VIS spectroscopic techniques. Thermal behavior of the product was studied using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA).

 
11. Electrochemical Polymerization of Para-Substituted Haloanilines

Atilla Cihaner and Ahmet M. Önal
Journal of Macromolecular Science, Part A: Pure and Applied Chemistry, 43, 153-163 (2006)

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Polyhaloanilines: poly(4-fluoroaniline) (P4FAN), poly(4-chloroaniline) (P4CAN), and poly(4-bromoaniline) (P4BAN), are synthesized from para-substituted haloaniline monomers; 4-fluoroaniline (4FAN), 4-chloroaniline (4CAN), and 4-bromoaniline (4BAN), respectively, via constant potential electrolysis (CPE) in acetonitrile-water mixture (1 : 1 v/v) with NaClO4 as supporting electrolyte. Prior to CPE, electrochemical behavior of the monomers were investigated in organic medium utilizing cyclic voltammetry (CV). The course of CPE was monitored using in-situ UV-VIS spectroscopic technique. Characterization of polymer products have been carried out using FT-IR and NMR spectroscopic techniques and thermal behaviors were studied using differential scanning calorimeter (DSC). Polyhaloanilines synthesized by electrochemical oxidation were doped using iodine and the change in the paramagnetic behavior was monitored by ESR, UV-VIS, and FT-IR.

 
10. Electrochemical Copolymerization of 2-Substituted Thiophene Derivative Linked by Polyether Bridge with Thiophene

Atilla Cihaner and Ahmet M. Önal
Journal of Electroanalytical Chemistry, 583, 104-108 (2005)

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New conducting copolymers have been synthesized via electrochemical oxidation of thiophene (Th) in the presence of monomer bis(2-thienyl)ethyl (I). Cyclic voltammetry (CV) studies showed that the presence of monomer I in the electrolytic solution greatly changes the CV behaviour of the formation of the polythiophene films. It is found that the increasing ratio of I was found to decrease electroactivity of copoly(I-Th). Electrochemical synthesis of copolymer films was achieved via constant potential electrolysis (CPE) in an electrolytic solution containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6) dissolved in CH3CN. Spectroelectrochemical (SPEL) properties of the films were investigated using UV–vis spectroscopic technique.

 
9. Synthesis of a Regular Polymer Containing Pseudo-Polyether Cages

Atilla Cihaner and Ahmet M. Önal
Synthetic Metals, 150, 39-45 (2005)

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A new compound consisting of 2-thienyl units linked by polyether bridge has been synthesized and its electrochemical polymerization was performed via constant potential electrolysis (CPE) in an electrolytic solution containing 0.1M tetrabutylammonium hexafluorophosphate (TBAPF6) dissolved in CH3CN. Chemical polymerization was carried out using FeCl3 as oxidizing agent. It is found that both methods gave the same polymer product without any cleavage of the polyether bridge between thiophene (Th) rings. Although as synthesized polymers exhibited no conductivity, they gain conductivity via chemical doping using I2 vapor exposure. The polymers were characterized using FTIR spectroscopic technique and I2 doping was monitored using in-situ electron spin resonance (ESR) spectroscopy. Thermal behavior of electrochemically prepared polymer was investigated using differential scanning calorimetry, DSC and thermogravimetric analysis, TGA.

 
8. Synthesis and Polymerization of 2- and 3-Substituted Thiophene Derivatives Linked by Polyether Bridges

Seha Tirkes, Atilla Cihaner and Ahmet M. Önal
Journal of Electroanalytical Chemistry, 573, 189-196 (2004)

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New compounds consisting of 2- and 3-thienyl units linked by polyether bridges have been synthesized and their electrochemical polymerization was performed via constant potential electrolysis (CPE) in an electrolytic solution containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6) dissolved in CH3CN. 2-Thienyl monomers (I and II), but not 3-thienyl monomers (III and IV), were also polymerized via chemical oxidation, which yielded broken p-conjugated polymer products. The polymers were characterized using 1H NMR and FT-IR spectroscopic techniques. It was found that both chemical and electrochemical oxidation of 2-thienyl monomers gave mainly poly(2,20-bithiophenemethylene) due to elimination of polyether chains during the polymerization reaction. On the other hand, electrochemical oxidation of 3-thienyl monomers resulted in corresponding polymers without any cleavage of polyether bridges. Spectroelectrochemical (SPEL) properties of the products were investigated using UV–Vis spectroscopic techniques.

 
7. Electrochemical Polymerization of 9-Fluorenone

Atilla Cihaner, Seha Tirke? and Ahmet M. Önal
Journal of Electroanalytical Chemistry, 568, 151-156 (2004)

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Electrochemical polymerization of 9-fluorenone, FO, was studied in CH2Cl2 solution with tetrabutylammonium tetrafluoroborate, TBABF4, as the electrolyte, via constant potential electrolysis, CPE. Prior to CPE, the redox behavior of FO was investigated in the same solvent/electrolytic medium using cyclic voltammetry, CV. CPE of FO yielded an insoluble polymer deposit on the electrode surface. The product was characterized by FTIR spectroscopy techniques. The redox and spectroelectrochemical, SPEL, behavior of the polymer were studied by CV and in situ UV–Vis spectrophotometric techniques at various potentials, respectively. The conductivity was measured using a two-probe technique and the paramagnetic behavior of the polymer was monitored using in situ ESR spectroscopy.

 
6. Spectroelectrochemical Investigation of the Anodic Oxidation of Dibenzo-18-Crown-6

Atilla Cihaner and Ahmet M. Önal
Journal of Electroanalytical Chemistry, 571, 159-157 (2004)

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Poly(dibenzo-18-crown-6) (poly-DB18C6) was synthesized by electrochemical oxidation of dibenzo-18-crown-6 (DB18C6) using a mixture of acetonitrile and dichloromethane as the solvent and tetrabutylammonium tetrafluoroborate (TBABF4) or tetrabutylammonium hexafluorophosphate (TBAPF6) as supporting electrolyte. The anodic polymerization of DB18C6 was investigated using in situ ESR and in situ UV–Vis spectroscopic techniques. Spectroelectrochemical (SPEL), properties and thermal analysis of the resulting polymers have been investigated using UV–Vis spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).

 
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