Browsing by Author "Cakal, Deniz"

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Citation - WoS: 29
Citation - Scopus: 31
Effect 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, Atilla; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
A 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.
Citation - WoS: 2
Citation - Scopus: 3
Effect of Phthalimide and Thieno[3,4-C]pyrrole Acceptors on P-Conjugated Donor-Acceptor Monomers: Experimental and Theoretical Investigations of Photophysical and Electrochemical Properties
(Pergamon-elsevier Science Ltd, 2023) Cakal, Deniz; Arabaci, Elif Demir; Yildirim, Erol; Cihaner, Atilla; Onal, Ahmet M.; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
In this study, two novel donor-acceptor-donor monomers were synthesized by coupling a phthalimide (PI) acceptor unit with thiophene (T) and ethylenedioxythiophene (EDOT (E)) donor units. These two novel PI-based monomers, namely 2-(2-ethylhexyl)-4,7-di(thiophen-2-yl)isoindoline-1,3-dione (T-PI) and 4,7-bis(2,3-dihydrothieno[3,4-b] [1,4]dioxin-5-yl)-2-(2-ethylhexyl)isoindoline-1,3-dione (E-PI), were fully characterized via UV-vis and fluorescence spectroscopy as well as electrochemical methods, and the results were directly compared with those of previously synthesized thieno[3,4-c]pyrrole-4,6-dione (TPD)-based analogues to report the results for four classes of monomers. In this regard, the ef-fects of different donor groups and structural modifications in the acceptor unit as changed from PI to TPD have been investigated to reveal the precise effect of the donor and acceptor on the optical and electrochemical properties of the monomers. All monomers exhibits an intramolecular charge transfer band in the low energy region due to strong donor and acceptor interactions. The oxidation and reduction potentials of the monomers are found to vary depending on the strengths of both donor and acceptor units. PI-based monomers show more positive oxidation and less negative reduction potentials than TPD-based analogues. Similarly, thiophene-based analogues reveal the same trend in their oxidation and reduction potentials as compared to EDOT-based analogues. Lastly, PI-based monomers could not undergo polymerization via electrochemical method, unlike TPD-based monomers, since the dihedral angle arising between donor and PI acceptor disturbs molecular planarity significantly, as demonstrated by first principle calculations.(C) 2023 Elsevier Ltd. All rights reserved.
Citation - WoS: 13
Citation - Scopus: 13
Effect of the Donor Units on the Properties of Fluorinated Acceptor Based Systems
(Elsevier Sci Ltd, 2021) Cakal, Deniz; Akdag, Akin; Cihaner, Atilla; Onal, Ahmet M.; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
A new series of monomers in the donor-acceptor-donor array, namely 5-fluoro-4,7-di(furan-2-yl)benzo[c][1,2,5] thiadiazole (F2BT-F), and 5-fluoro-4,7-di(selenophen-2-yl)benzo[c][1,2,5] thiadiazole (S2BT-F), bearing 5-fluorobenzo[c][1,2,5]-thiadiazole as the acceptor moiety and furan and selenophene as the electron donating groups was synthesized and polymerized electrochemically. To compare heteroatom effect, thiophene analogue of newly synthesized (FBT)-B-2-F and S2BT-F namely, (5-fluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5] thiadiazole (T2BT-F)) and its corresponding polymer were also synthesized. Effect of donor units on the electrochemical and optical properties of fluorinated acceptor based systems was investigated in terms of the effect of different sized heteroatoms in five-membered rings on the dihedral angle and planarity. Theoretical calculations also suggested a deviation from planarity upon fluorination. Moreover, electrochemically obtained polymers possess low bandgap values (1.62 eV-1.68 eV for PF2BT-F and PS2BT-F, respectively) and exhibited electrochromic properties with relatively low switching times.
Citation - WoS: 7
Citation - Scopus: 7
Electrochemical and optical properties of dicyclohexylmethyl substituted poly(3,4-propylenedioxythiophene) analogue
(Wiley, 2018) Cakal, Deniz; Cihaner, Atilla; Onal, Ahmet M.; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
An analogue of disubstituted 3,4-propylenedioxythiophenes, namely 3,3-bis(cyclohexylmethyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin (ProDOT-CycHex(2)), was synthesized and its electrochemical polymerization was carried out successfully in an electrolyte solution of 0.1 M tetrabutylammonium hexafluorophosphate dissolved in a mixture of acetonitrile and dichloromethane (3/1: v/v). The corresponding polymer called PProDOT-CycHex(2) has a reduced band gap of 1.85 eV and an electrochromic property: blue/violet when neutralized and highly transparent when oxidized. Also, PProDOT-CycHex(2) film exhibited faster response time (0.7 s) and higher coloration efficiency (769 cm(2)/C) during oxidation when compared to its benzyl substituted analogue. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46214.
Citation - WoS: 10
Citation - Scopus: 10
Electrochemical 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.; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
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.
Citation - WoS: 9
Citation - Scopus: 10
Polyhedral Oligomeric Silsesquioxanes Appended Conjugated Soluble Polymers Based on Thieno[3,4-C]pyrrole Acceptor Unit
(Pergamon-elsevier Science Ltd, 2021) Cakal, Deniz; Cihaner, Atilla; Onal, Ahmet M.; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
A series of new donor-acceptor-donor type fluorescent molecules incorporating thieno[3,4-c]pyrrole-4,6-dione (TPD) as the acceptor unit were synthesized. TPD acceptor unit was modified with polyhedral oligomeric silsesquioxanes (POSS) cages and integrated with thiophene and alkylenedioxythiophene derivatives (3,4-ethylenedioxythiophene (EDOT) and 3,4-propylenedioxythiophene (ProDOT)) using Stille coupling reaction. The monomers, T-2-POSS, E-2-POSS, and P-2-POSS, were polymerized successfully via electrochemical and chemical polymerization techniques. As a fingerprint of D-A-D monomers, all monomers showed dual band characteristics due to intramolecular charge transfer. Soluble polymers exhibited reversible electrochromic responses electrochemically and chemically with fast switching times and high coloration efficiencies. E-2-POSS and its polymer PE2-POSS exhibited the lowest oxidation potential and band gap values as compared to their thiophene and ProDOT analogs. Also, P-2-POSS and its chemically obtained fluorescent polymer PP2-POSS-C represented high sensitivity towards Fe2+ and Fe3+ ions, which makes them potential candidates to be amenable for use in ion sensing. (C) 2021 Elsevier Ltd. All rights reserved.
Citation - WoS: 6
Citation - Scopus: 6
Side Chain Effect on the Electrochemical and Optical Properties of Thieno[3,4-c]pyrrole-4,6-dione Based Donor-Acceptor Donor Type Monomers and Polymers
(Royal Soc Chemistry, 2023) Cakal, Deniz; Arabaci, Elif Demir; Yildirim, Erol; Cihaner, Atilla; Onal, Ahmet M.; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
In organic pi-conjugated materials, side chains play great roles that impact far beyond solubility. In this work, we mainly focused on the synthesis of new donor-acceptor-donor (D-A-D) type conjugated monomers and their corresponding polymers appending thieno[3,4-c]pyrrole-4,6-dione (TPD) acceptor with a new side chain, fluorene (Fl), to investigate the side chain effect. In this context, to reveal the precise effect of the side chains on the optical and electrochemical properties of the monomers and polymers synthesized in this work, four series of D-A-D monomers, each containing a TPD core unit with a different side chain, are compared and discussed in relation to each other. Notably, it was discovered that the TPD acceptor unit can be modified with any functional group other than common alkyl chains to impart new functionalities by maintaining their superior optoelectronic properties. New types of side chains can be used to tune the physical characteristics, such as solubility, absorption, emission, and molecular packing. In this work, Fl-appended monomers as a new class of D-A-D type pi-conjugated molecules containing 3,4-ethylenedioxythiophene (EDOT (E)) and 3,4-propylenedioxythiophene (ProDOT (P)) donor units were studied and it was found that 1,3-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-5-(9H-fluoren-2-yl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione (E(Fl)) and 1,3-bis(3,3-didecyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-6-yl)-5-(9H-fluoren-2-yl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione (P(Fl)) exhibited reasonable quantum yields and their corresponding polymers revealed ambipolar character with slightly lower band gap as compared to the previous analogues containing other side chains. Observed experimental results were elucidated by first principle calculations. In this paper, we discussed that using side chain engineering is an effective strategy for improving next-generation organic pi-conjugated materials with the desired properties.
Synthesis and Characterization of a Luminol Based Chemiluminescent Trimeric System
(Springer/plenum Publishers, 2023) Kesimal, Busra; Balci, Burcu; Cakal, Deniz; Onal, Ahmet M.; Cihaner, Atilla; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
A luminol based chemiluminescent trimeric system, namely 2,3-dihydro-5,8-di(thiophen-2-yl)phthalazine-1,4-dione (T2B-Lum), bearing thiophene rings as donor units and 2,3-dihydrophthalazine-1,4-dione as an acceptor unit was synthesized in two steps via donor-acceptor-donor approach using two different methods. It was found that T2B-Lum emits chemiluminescent light when exposed to H2O2 in a basic medium, and the presence of substituents and the type of aromatic ring bearing chemiluminescent active group have a direct effect on the compound's sensitivity. Among the members of a large family of metal ions, fluorescent and chemiluminescent T2B-Lum exhibited high sensitivity to Cu2+ and Fe3+ ions. Except for other metal cations (silver(I), cadmium(II), cobalt(II), iron(III), lithium(I), magnesium(II), manganese(II), nickel(II), zinc(II)), it has been observed that T2B-Lum is mostly sensitive to copper(II) ions with a detection limit value of 2.2 x 10(- 3) M. On the other hand, T2B-Lum was also found to exhibit a high sensitivity to extremely dilute aqueous solutions (e.g., 1:50.000 dilution) of blood samples, making it a promising candidate for use in forensic applications.
Citation - WoS: 24
Citation - Scopus: 23
Synthesis 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.; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
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.
Synthesis and Electropolymerization of a Selenophene Based Chemiluminescent Monomer and Its Use in Blood Detection
(Elsevier Sci Ltd, 2025) Balci, Burcu; Cakal, Deniz; Cihaner, Atilla; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
A new selenophene based trimeric chemiluminescent compound, namely 5,7-di(selenophen-2-yl)-2,3-dihydrothieno[3,4-d]pyridazine-1,4-dione (S2T-Lum), was synthesized in two steps via electron donor-acceptor-donor approach. Its chemiluminescent reaction with hydrogen peroxide was investigated in an alkaline solution in the presence of various catalysts such as different metal ions, hemin and blood samples and the results were compared with its thiophene analogue (T2T-Lum) and luminol. It was found that S2T-Lum was very sensitive to copper(II) and iron(III) ions, and blood samples. Also, it can be easily concluded that S2T-Lum as a new member of luminol type compounds is a potential candidate for the detection of blood findings in forensic science. Furthermore, S2T-Lum has an irreversible oxidation peak at 1.28 V vs Ag/AgCl, which is responsible from its electropolymerization. S2T-Lum was successfully polymerized electrochemically via potentiodynamic electrolysis without cleavage of its chemiluminescent active appendage. To the best of our knowledge, its corresponding polymer PS2T-Lum film is the first member of selenophene based luminol type electroactive polymers.
Citation - WoS: 9
Citation - Scopus: 9
Synthesis and Electropolymerization of Donor-Acceptor Type Monomers Based on Azobenzene-Substituted Thieno[3,4-C]pyrrole Acceptors
(Pergamon-elsevier Science Ltd, 2021) Cakal, Deniz; Cihaner, Atilla; Onal, Ahmet M.; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
By using donor-acceptor-donor approach, a new series of photo responsive and electroactive trimeric monomers, namely (E)-5-(4-(phenyldiazenyl)phenyl)-1,3-di(thiophen-2-yl)-4H-thieno[3,4- c]pyrrole-4,6(5H)-dione (T-2-AB ), (E)-1,3-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-5-(4-(phenyldiazenyl)phenyl)- 4H-thieno[3,4-c]pyrrole-4,6(5H)-dione (E-2-AB ) and (E)-1,3-bis(3,3-didecyl-3,4-dihydro-2H-thieno[3,4- b][1,4]dioxepin-6-yl)-5-(4-(phenyldiazenyl)phenyl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione (P-2-AB ), was synthesized and characterized. The oxidation potential of the monomers was controlled by the strength of donor units and the following trend was observed for them: Eox (T-2-AB ) > E-ox (P-2-AB ) > E-ox (E-2-AB ). Also, a similar behavior was observed for their band gap values: 2.53 eV for T-2-AB , 2.18 eV for E-2-AB and 2.28 eV for P-2-AB . The monomers were polymerized successfully via electrochemical methods in order to give electrochromic ambipolar conjugated polymers bearing narrow optical band gaps: 1.71 eV, 1.54 eV and 1.68 eV for PT2-AB, PE2-AB , and PP2-AB, respectively. Also, the polymer films are stable and robust. Moreover, the three monomers and soluble PP(2-)AB polymer exhibited trans to cis photo-isomerization upon irradiation with UV light. In addition, the photoluminescence intensity of the monomers in toluene was found to decrease with increasing acid concentration, which makes them potential candidates to be amenable as pH sensors. (C) 2021 Elsevier Ltd. All rights reserved.
Citation - WoS: 15
Citation - Scopus: 16
Synthesis 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.; Chemical Engineering; 06. School Of Engineering; 01. Atılım University
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.