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Article Citation - WoS: 11Citation - Scopus: 11Electrochemical and Optical Properties of Substituted Phthalimide Based Monomers and Electrochemical Polymerization of 3,4-Ethylenedioxythiophene Oligomeric Silsesquioxane (poss) Analogue(Elsevier Sci Ltd, 2019) Cakal, Deniz; Ertan, Salih; Cihaner, Atilla; Onal, Ahmet M.A new series of donor-acceptor-donor type trimeric monomers bearing substituted phthalimide units as acceptor units and thiophene and 3,4-ethylenedioxythiophene (EDOT) as donor units was synthesized and characterized. The strength of acceptor units and intramolecular charge transfer between donor and acceptor units were investigated by using electrochemical and optical methods. The main advantage of phthalimide unit over other acceptor units is the ease of its functionalizability. Thus, utilizing this property, a phthalimide derivative (E2P-POSS) bearing polyhedral oligomeric silsesquioxane (POSS) cage was introduced successfully with EDOT and polymerized electrochemically. The corresponding electroactive polymer, PE2P-POSS, has a band gap of 1.72 eV and is an electrochromic polymer: gray when neutralized and eggplant purple when oxidized.Article Citation - WoS: 30Citation - Scopus: 32Effect of Fluorine Substituted Benzothiadiazole on Electro-Optical Properties of Donor-Acceptor Type Monomers and Their Polymers(Elsevier Sci Ltd, 2020) Cakal, Deniz; Ercan, Yunus Emre; Onal, Ahmet M.; Cihaner, AtillaA series of trimeric monomers bearing thiophene donor units and fluorinated analogues of benzothiadiazole acceptor units was synthesized via donor-acceptor-donor approach and polymerized electrochemically in order to investigate the effect of fluorine atom on electro-optical properties of both monomers and their corresponding polymers. All monomers exhibited solvatochromic and fluorescent properties. The introduction of fluorine atom into the conjugated backbone increased the oxidation potentials. Upon moving from nonfluorinated to fully fluorinated analogues, the oxidation potential shifts anodically from 1.30 V to 1.7 V. As in the case of monomers, the fluorine atom substitution also resulted in a decrease in the HOMO energy level of the corresponding polymers, leading to an increase in the electrochemical band gap energy (1.71-1.97 eV). This result can be attributed to deviations from planarity and also to decrease in the effective conjugation length. The polymeric film also exhibited electrochromic properties under various external potentials. Switching time and coloration efficiency values decreased with increasing number of fluorine atom substitution.Article Citation - WoS: 24Citation - Scopus: 23Synthesis and Electrochemical Polymerization of D-A Type Monomers With Thieno [3,4-c] Pyrrole-4,6 Acceptor Unit(Elsevier Sci Ltd, 2018) Cakal, Deniz; Ertan, Salih; Cihaner, Atilla; Onal, Ahmet M.In this study, three new donor-acceptor-donor type monomers bearing 1,3-dibromo-5-(2-ethylhexyl)-4H-thieno [3,4-c]pyrrole- 4,6(5H)-dione (A) as an acceptor unit and thiophene, 3,4-ethylenedioxythiophene (EDOT) and 3,3-didecy1-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine (didecyl-ProDOT) as donor units were synthesized via Stille cross-coupling reaction and their electrochemical polymerization by repetitive cycling was reported. The electrochemical and optical properties of the monomers ((5-(2-ethyl-liexyl)-1,3-di(thienyl-2-yl)-4H-thienolr-3,4-cl pyrrole-4,6(5H)-dione (TAT), 1,3-bis(2,3-dihydrothieno[3,4-1)] (1,4]dioicin-5-yl)-5-(2-ethylhexyl)-4H-thieno(3,4-c) pyrrole-4,6-(5H)-dione (EAE) and 1,3-bis(3,3-didecyl-3,4-dihydro-2H-thieno[3,4-1)111,41-dioxepin-6-yl)-5-(2-ethylhexyl)-4H-thieno[3,4-apyrrole-4,6(5H)-dione (PAP)) and their corresponding polymers called PTAT, PEAE and PPAP were investigated and it was found that EDOT units containing monomer and polymer (EAE and PEAE) have lower oxidation potentials and lower band gap value as compared to didecyl-ProDOT and thiophene units containing monomers and polymers (PAP, TAT and PPAP, PTAT). Spectroelectrochemical investigations conducted on electrochemically obtained polymer films revealed that polymer films exhibited electrochromic behaviors: brick red to gray for PTAT, blue/violet to highly sky blue for PEAE and blue to highly light blue for PPAP in their neutral and oxidized states, respectively. Moreover, PAP was also polymerized chemically using FeC13 as an oxidizing agent. Both chemically and electrochemically obtained PPAP were found to be soluble in some organic solvents and their dichloromethane solutions can be reversibly oxidized and reduced using antimony pentachloride and hydrazine hydrate solutions, respectively.Article Citation - WoS: 16Citation - Scopus: 16Synthesis and electropolymerization of thieno[3,4-c]pyrrole-4,6-dione based donor-acceptor-donor type monomers(Elsevier Science Sa, 2020) Cakal, Deniz; Cihaner, Atilla; Onal, Ahmet M.Two monomers containing thieno [3,4-c]pyrrole-4,6-dione (TP) acceptor units, namely 5-(2-ethylhexyl)-1,3-di (furan2-yl)-4H-thieno [3,4-c]pyrrole-4,6(5H)-dione (FTPF) and 5-(2-ethylhexyl)-1,3-di (selenophen-2-yl)-4H-thieno[3,4-c] pyrrole-4,6(5H)-dione (STPS), were synthesized via donor-acceptor-donor approach. Under the same template structure, the effect of heteroatom of the donor unit on redox and optical properties of the monomers and their corresponding polymers obtained via electrochemical method (PFTPF and PSTPS) were investigated. The results were also compared to their thiophene analogues 5-(2- ethylhexyl)-1,3-di (thiophen-2-yl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione (TTPT) as the monomer and PTTPT as the polymer. Three monomers exhibited dual absorption bands one at high energy region due to the pi-pi* transition and the other one at low energy region which might be attributed to intramolecular charge transfer (ICT). An increase in ICT and a decrease both in the band gap and quantum yield was observed with increasing size of the heteroatomof the donor units. The oxidation potentials of the monomers and that of their corresponding polymer films were found to follow the order of decreasing aromatization energy from thiophene to furan (i.e thiophene > selenophene > furan). Also, heavy-atom substitution (PSTPS) effect showed itself by narrowing the optical band gap of the neutral state electrochromic polymer films: 1.90 eV for PFTPF, 1.82 eV for PTTPT and 1.76 eV for PSTPS.
