Browsing by Author "Ergun, Emine Gul Cansu"

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A benzimidazole-based turn-off fluorescent sensor for selective detection of mercury (II)
(2020) Ergun, Emine Gul Cansu; Ertas, Gulay; Eroglu, Deniz; 0000-0002-3941-4345; I-7385-2017
In this study, potential fluorescent sensing ability of a donor-acceptor-donor type conjugated molecule over various metal ions (Ni(II), Zn(II), Cu(II), Cd(II), Pb(II), Fe(II), Fe(III), As(III), Se(IV), Hg(I) and Hg(II)) was investigated. The sensor basically includes benzimidazole and 3,4-propylenedioxythiophene as the acceptor and donor units, respectively. Solution of the sensor in tetrahydrofuran exhibits an emission with having a maximum at 632 nm. Since having insolubility of some ions in tetrahydrofuran, ion solutions were prepared in deionized water and titrations were performed by stepwise additions of ions into sensor solution in tetrahydrofuran. The control experiment including only deionized water resulted in 7 nm red-shift and 71 % quenching in the emission band. On the other hand, upon 1.07 eq. addition of Hg(II), 25 nm red-shift and 88 % fluorescent quenching were observed, exhibiting a difference among other ions. The corresponding spectral-shift and quenching amounts in the emission were found to be time-dependent and reach to equilibrium after 10 min. Studies showed that Hg(II) in aqueous solutions can be selectively detected even in the presence of other ions. Moreover, presence of Hg(II) (0.36 eq or beyond) changed the color of the sensor solution from pink to pale violet, which can be followed by the naked eye. In the light of these results, the reported sensor can be assigned as a fluorescent and a chromogenic sensor for Hg(II) detection. Limit of quantification was found to be 39.2 nM, which is comparable to the most of the fluorescent Hg(II) sensors in the literature.
A classified and comparative review of Poly (2,5-dithienyl-N-substituted-pyrrole) derivatives for electrochromic applications
(2022) Carbas, Buket Bezgin; Ergun, Emine Gul Cansu
Poly(2,5-dithienyl-1-substituted-pyrrole) derivatives are one of the important classes for conducting polymers, exhibiting versatile electrochromic property besides used material in a broad range of smart applications. This review offers an overview of various SNS derivatives, mostly for electrochromic applications. In this compilation, the designed, synthesized and electrochemically and optically characterized conducting polymers of SNS derivatives in the literature up to today have been classified and comparatively discussed. The polymers of the SNS derivatives collected here have been prepared mostly by electrochemical techniques. According to N-substitutions form pyrrole unit, P(SNS) derivatives were grouped into five sections: N- alkyl-, phenyl-, amine/amide, homo/heterocyclic-, and crosslinked substituted derivatives. Each section mainly includes the structure-property relationship and the comparison of the effect of substitutions on the electrochromic properties of the resulting polymers.
Cross-exchange of donor units in donor-acceptor-donor type conjugated molecules: Effect of symmetrical and unsymmetrical linkage on the electrochemical and optical properties
(2020) Eroglu, Deniz; Ergun, Emine Gul Cansu; Onal, Ahmet M.; 0000-0002-3941-4345; I-7385-2017
A series of donor-acceptor-donor type molecules were synthesized using carbazole (C) and thiophene (T) as donor units. The donors were connected symmetrically and unsymmetrically to the acceptor unit of benzothiadiazole (B). With having four combinations, CBC, CBT, TBT and CTBTC, changes in the electrochemical and optical behaviors of the monomers were investigated using cyclic voltammetry, differential pulse voltammetry, UV-Vis and Fluorescence spectrometry techniques. Replacing one of the symmetrical C units in CBC with T unit caused a slight red shift in lower energy absorption band. On the other hand, having both C and T units symmetrically in the monomer structure exhibited about 70 nm red shift in the optical absorption. Electrochemical polymerization of the monomers was studied via potential cycling. In the case of formation of polymer films, the effect of exchange and combination of the donors on the electrochemical and optical properties was investigated. (C) 2020 Elsevier Ltd. All rights reserved.
An electrochemically and optically stable electrochromic polymer film based on EDOT and 1,2,3,4-tetrahydrophenazine
(2019) Ergun, Emine Gul Cansu; Eroglu, Deniz
In this work, 3,4-ethylenedioxythiophene (EDOT) and 1,2,3,4-tetrahydrophenazine based donor-acceptor-donor type monomer (EBE) was synthesized, electropolymerized and the resulting polymer film (P(EBE)) was investigated in terms of its electrochemical and spectroelectrochemical properties. The polymer film showed excellent electrochemical stability upon 1000 switchings by saving almost full of its electroactivity. Moreover, 95% of the optical contrast was maintained after 500 switchings. The optical band gap value was calculated using Tauc Plot method and found as 1.5 eV. P(EBE) film revealed multichromic behaviour between its fully neutral and oxidized states; dark cyanish-green at - 0.8 V, more green at - 0.5 V and transmissive green beyond 0.6 V potentials. Finally, a dual type electrochromic device (ECD) was constructed with P(EBE) and poly(3,4-ethylenedioxythiophene) (PEDOT) films and the spectroelectrochemical behaviour of ECD was depicted.
Electrochromic copolymers of 2,5-dithienyl-N-substituted-pyrrole (SNS) derivatives with EDOT: Properties and electrochromic device applications
(2022) Ergun, Emine Gul Cansu; Carbas, Buket Bezgin
2,5-dithienyl-N-substituted-pyrrole (SNS) derivatives are one of the most preferred conjugated systems for obtaining conducting polymers since they have low oxidation potential and ease of electrochemical polymerization. SNS backbone can be substituted from the nitrogen atom on the pyrrole unit and resulting SNS derivatives allow fine tuning on the spectroelectrochemical properties. Moreover, copolymerization of SNS derivatives leads to further tuning or enhancement on the features of the obtained copolymer. 3,4-Ethylenedioxythiophene (EDOT) is the most promising conjugated unit used in copolymerization of conjugated systems. In this review, electrochemically synthesized conducting copolymers of SNS derivatives with EDOT in the literature were collected and discussed. According to N-substitutions, SNS derivatives in copolymers were grouped into four sections: phenyl-, amine-, alkyl-, and crosslinked- substituted derivatives. In each section, the effect of different substitutions and amount of EDOT incorporation on the electrochromic properties of the resulting copolymers were both evaluated in the text and summarized in the tables. Electrochromic device applications, if exist, of related copolymers were also discussed. Here, an overview is presented of available electrochromic copolymers for SNS derivatives with EDOT, providing a perspective for scientists aiming to design new SNS derivatives for copolymerization.
Electrochromic Insight on Electro-Deposited Copolymers of Push-Pull Conjugated Systems with 3,4-Ethylenedioxythiophene (EDOT) and Other Conjugated Units
(2023) Ergun, Emine Gul Cansu; Hacioglu, Serife Ozdemir
Third generation conducting polymers (CP) are push-pull type conjugated systems, which include both electron pushing and pulling units in their chemical structure. Push-pull design enables coarse and fine tuning in the electro-optical properties of the resulting CP such as lowering the band gap and enhancing electrochromic properties. Push-pull CPs have been widely used for various applications such as electrochromic devices, displays, light emitting diodes, organic solar cells, field effect transistors, electrochemical and optical sensors etc. This review aims to collect electrochemically synthesized CPs of push-pull systems in the literature, up to 2023. Most of the studies include 3,4-ethylenedioxythiophene (EDOT) as co-monomers, but there are also other studies such as obtaining push-pull type CPs by copolymerization, and copolymerization of push-pull systems with other units. Each case is discussed in separate sections. In the scope of this review, only electrochemical copolymerization studies are selected, and the effect of monomer feed ratio and the polymerization conditions on the electrochromic properties of the resulting copolymers are discussed and summarized in tables. This collection can serve as a guide for upcoming copolymerization studies, by giving an insight into optical and electrochromic properties of various copolymers of push-pull systems so far. A comprehensive literature survey about electrochemical copolymerization of push-pull type conjugated systems with 3,4-ethylenedioxythiophene (EDOT) and other conjugated units. Effect of monomer feed ratio and polymerization conditions on the electrochromic properties of resulting copolymers were discussed.image
Hunting Black Color via Absorption Engineering: EDOT and Thiophene-Benzothiadiazole Based Black-To-Transmissive Copolymer and Its Electrochromic Device Application
(2022) Ergun, Emine Gul Cansu; Akbayrak, Merve
Neutral state black electrochromics are prominent materials for smart applications such as displays, car rear views, e-papers etc. This work has aimed to obtain a neutral state black electrochromic polymer, by tuning the optical absorbance to whole visible region. Two monomers, 4,7-bis(5-(thiophen-2-yl)thiophen-2-yl)benzo[c] [1,2,5]thiadiazole (TTBTT) and 3,4-ethylenedioxythiophene (EDOT), were selected according to their complementary absorbance behaviors, and they were combined in the same polymer backbone via electrochemical copolymerization technique. Copolymerization was performed using three different monomer feed ratios (2:1, 1:1 and 1:2 (EDOT: TTBTT)). Even though all the copolymers exhibited dark to transmissive colors from neutral to oxidized states, changing the monomer feed resulted in different optical contrast, switching response and color hues for each copolymer. The higher optical contrast (from 17% to 27%) and faster switching response (from 3.6 s to 1.8 s) were recorded as EDOT unit increase in the copolymer chain. A dual type electrochromic device was also constructed using the copolymer and the resulting device was successfully changed its color from black to transmissive.
Neutral-State Black Electrochromic Polymer With Enhanced Supercapacitor Electrode Performance
(JOURNAL OF ENERGY STORAGE, 2024-11-15) Ergun, Emine Gul Cansu; Onal, Ahmet M.
Neutral-state black electrochromic materials are attracting attention, especially in the applications of displays, car-rear views, sensors, and electronic papers. This study aimed to obtain a black electrochromic polymer via electrochemical techniques. For this aim, the monomer of a green-electrochromic polymer, 4-(3,3-dihexyl-3,4dihydro-2H-thieno[3,4-b][1,4]dioxepin-6-yl)-7-(3,3-dihexyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-8-yl)-2cyclohexyl-2H-benzo-[d]imidazole (PBP), was copolymerized with 3,4-ethylenedioxythiophene (EDOT) with 2:1 and 2:2 (PBP: EDOT) monomer feed ratios. The resulting copolymer films were investigated in terms of their electrochromic properties. Equal feeded copolymerization resulted in a neutral-state black electrochromic polymer (L:11.5, a:1.5, b:-2.55) with satisfying responses in the electrochromic device application (100 % electroactivity maintenance after 300 switches with 1.4 s response time). Furthermore, increasing the quantity of EDOT in the copolymer chain improved the capacitive characteristics, showing that the equal-fed copolymer is a good candidate for a supercapacitor electrode (4.07 mF/cm(2)). The supercapacitor device application showed that the equal feeded copolymer has superior specific capacitance retention of 97 % after 500 charge/discharge cycle, with 100 % coulombic efficiency in each cycle. Moreover, the supercapacitor is capable of lighting a 1.5 V LED for >30 s.
Three in One Sensor: A Fluorometric, Colorimetric and Paper Based Probe for the Selective Detection of Mercury(Ii)
(2021) Ergun, Emine Gul Cansu
In this work, a 3,4-ethylenedioxythiophene and tetrahydrophenazine based donor-acceptor-donor-type conjugated molecule was used for the first time as a turn-off fluorescence sensor for the detection of mercury (Hg2+) ions. Eleven metal ions (As3+, Cd2+, Cu2+, Fe2+, Fe3+, Hg+, Hg2+, K+, Ni2+, Se4+ and Zn2+) were tested and the proposed sensor exhibited almost 100% quenching in the fluorescence emission only when interacting with Hg2+ ions. Moreover, the sensor changed its color from yellow to blue upon Hg2+ addition, which indicates that the sensor is not only a fluorescence sensor but also a chromogenic sensor for Hg2+ detection. The solid state behavior was tested by preparing a simple paper-based sensor, and complete fluorescence quenching in the presence of Hg2+ was successfully obtained. The stoichiometry between the sensor and Hg2+ was found to be 1 : 1. The limit of detection (LOD) and the practical quantitation limit (PQL) were calculated to be 8.0 ppm and 26.3 ppm, respectively. The sensor was found to be more sensitive under acidic conditions, and the LOD decreased up to 3.0 ppm in the pH range of 1.6-2.3.
Toward Camouflage Colors by Electrochemical Copolymerization
(2023) Ergun, Emine Gul Cansu; Carbas, Buket Bezgin
In this paper, a new electrochromic copolymer containing 6,9-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-1,2,3,4-tetrahydrophenazine (EBE) and 4-(9-benzyl-9H-carbazol-3-yl)-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (CBT) in the main chain was reported. The homopolymers, (Poly(EBE) and Poly(CBT)), were also prepared via electrochemical polymerization and their electrochemical, spectroelectrochemical and electrochromic properties were analyzed in order to compare their properties with those of copolymer (Poly(EBE-co-CBT)). The copolymer exhibited good switching property for military camouflage necessities with color change from hues of brown to green. Furthermore, it has been tried to analyze the effects of combination of two donor-acceptor-donor (DAD) type monomers with different symmetries on the copolymer properties. A viable strategy for electrochromic adaptive camouflage was presented. New electrochromic copolymer film containing 6,9-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-1,2,3,4-tetrahydrophenazine and 4-(9-benzyl-9H-carbazol-3-yl)-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole in the main chain was synthesized using electrochemical polymerization technique. The resulting copolymer film matched the military camouflage necessities with having color changes from hues of brown to green. Moreover, an "asymmetric and symmetric donor-acceptor-donor type monomeric combination" in an electrodeposited copolymer film was first time presented.image