Person: ALTINÖLÇEK GÜLTEKİN, NURAY
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ALTINÖLÇEK GÜLTEKİN
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NURAY
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Publication A carbazole-based fluorescent turn-off chemosensor for iron (II/III) detection in a dimethyl sulfoxide(Springer/Plenum Publishers, 2023-01-31) Battal, Ahmet; Kassa, Solomon Bezabeh; Gültekin, Nuray Altınölçek; Tavaslı, Mustafa; Önganer, Yavuz; ALTINÖLÇEK GÜLTEKİN, NURAY; TAVASLI, MUSTAFA; Fen Edebiyat Fakültesi; Kimya Bölümü; 0000-0002-9466-1111 ; HNL-5314-2023; AAB-1630-2020We designed a novel carbazole-based chemosensor from 2-(N-hexylcarbazol-3'-yl)-pyridine-5-carbaldehyde which was named probe 7b. The main purpose of this study is to investigate whether metal ions in liquid media can be detected with probe 7b. The details were presented in this paper. First, the molecular absorption and fluorescence properties of probe 7b were characterized by spectrophotometers. Then, several methods were applied to check its sensing properties. The results showed that probe 7b has a sense towards Fe3+ ion than other interfering metal ions. The selectivity and sensitivity of probe 7b towards Fe3+ were very satisfactory to use in applications. Also, it was observed that when aqueous Fe3+ ion solutions were added to probe 7b in dimethyl sulfoxide (DMSO), the fluorescence intensity of probe 7b decreased. This situation (turn-off of emission) is due to the paramagnetic effect between probe 7b and Fe3+ ions. The limit of detection (LOD) value was found as 1.38 nM for probe 7b. This value is very small to compete with its counterparts in the literature. A real sample experiment indicated that probe 7b can detect Fe3+ ions more than other ions in real media, too. As a result, it was deduced that probe 7b is a very strong candidate to use in sensor technology.Publication Carbazole-based D-π-A molecules: Determining the photophysical properties and comparing ICT effects of π-spacer and acceptor groups(Elsevier, 2021-04-11) Altınölçek, Nuray; Battal, Ahmet; Vardallı, Cemre Nur; Tavaslı, Mustafa; Yu, Holly A.; Peveler, William J.; Skabara, Peter J.; ALTINÖLÇEK GÜLTEKİN, NURAY; Vardalli, Cemre Nur; TAVASLI, MUSTAFA; Fen Edebiyat Fakültesi; Kimya Bölümü; 0000-0002-9466-1111; JCN-8292-2023 ; EDG-8300-2022 ; AAB-1630-20204-(9'-Hexylcarbazol-3'-yl)benzaldehyde (Cz-Ph-CHO: 4 ) and 4-(9'-hexylcarbazol-3'- yl)benzylidenemalononitrile (Cz-Ph-CN: 5 ) were synthesised with the structure of D-pi-A,where carbazole, phenylene and formyl/dicyanovinyl groups act as electron donor (D), pi-spacer (pi) and electron acceptor (A) units, respectively. The thermal, electrochemical, optical and intramolecular charge transfer (ICT) properties of compounds 4 and 5 were investigated. Compounds 4 and 5 , in particular their ICT behaviour, were also compared with the closely related structure, 2-(9'-hexylcarbazol-3'-yl)-5-pyridinecarbaldehyde (Cz-Py-CHO: 7 ). For the purpose of tuning chemical structure to obtain targeted properties, electrochemical data and absorption and emission measurements suggest that the dicyanovinyl unit in compound 5 is a better acceptor than formyl in compound 4, and that pyridine in compound 7 is a better pi-spacer than benzene in compound 4 , in exerting ICT characteristics such as fluorosolvatochromism and Stokes shifts.Publication A red-orange carbazole-based iridium(III) complex: Synthesis, thermal, optical and electrochemical properties and OLED application(Elsevier Science, 2021-07-21) Altınölçek, Nuray; Battal, Ahmet; Tavaslı, Mustafa; Cameron, Joseph; Peveler, William J.; Yu, Holly A.; Skabara, Peter J.; Fairbairn, Nicola J.; Hedley, Gordon J.; ALTINÖLÇEK GÜLTEKİN, NURAY; TAVASLI, MUSTAFA; Fen Edebiyat Fakültesi; Kimya Bölümü; 0000-0002-9466-1111; JCN-8292-2023; AAB-1630-2020A novel heteroleptic iridium(III) acetylacetonate (acac) complex, (L-5-CHO)(2)Ir(acac) (3b), was synthesised from 2-(9'-hexylcarbazole-3'-yl)-5-formylpyridine (L-5-CHO) (1b). The complex 3b was determined to be thermally and electrochemically stable. The photoluminescence properties of the compound were studied, with a dichloromethane solution of 3b giving structureless emission at 662 nm, showing that the formyl group red-shifted the emission by 151 nm compared to the parent complex. Complex 3b was also shown to possess a moderate photoluminescence quantum yield (67%) and a short emission lifetime (tau = 280 ns). Organic light-emitting diodes (OLEDs) were fabricated with a solution-processed emissive layer (EML) consisting of poly(N-vinylcarbazole) (PVK), 2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD) and iridium complex (3b). The OLEDs containing complex 3b showed red-orange electroluminescence (EL) at 624 nm. The influence of the host materials was studied and the best performance was achieved with both PVK and PBD in the emissive layer, with the resulting OLEDs exhibiting a current efficiency of 0.84 cd/A, a power efficiency of 0.20 lm/W, and an external quantum efficiency (EQE) of 0.66% at a brightness of 2548 cd/m(2).Publication A reaction-based carbazole-dicyanovinyl conjugated colorimetric and ratiometric fluorescent probe for selective detection of cyanide ions(Pergamon-Elsevier Science Ltd, 2023-09-07) Battal, Ahmet; Kassa, Solomon Bezabeh; Gültekin, Nuray Altınolçek; Tavaslı, Mustafa; Onganer, Yavuz; ALTINÖLÇEK GÜLTEKİN, NURAY; TAVASLI, MUSTAFA; Fen Edebiyat Fakültesi; Kimya Bölümü; 0000-0002-9466-1111 ; HNL-5314-2023; AAB-1630-2020In the present work, 4-(9'-hexylcarbazol-3'-yl)benzylidenemalononitrile 5 (probe L) was tested as a colorimetric and ratiometric fluorescent probe in dimethyl sulfoxide (DMSO) medium towards anions, cations and neutral molecules. The sensing properties of probe L were investigated by using UV-Vis absorption and fluorescence spectroscopy techniques. Probe L showed selectivity and sensitivity towards cyanide ions (CN-) in the presence of analytes used. Upon the addition of CN-, intramolecular charge transfer (ICT) band at 425 nm in UV spectrum disappeared. In addition, ICT emission intensity at 593 nm decreased and ligand-centred (LC) emission intensity at 480 nm increased. These findings indicate that nucleophilic conjugate addition of CN- to the dicyanovinyl group of probe L successfully occurs, hence forming a new adduct between probe L and CN-. In this adduct, pi-conjugation was partially blocked, and the ICT transfer was hindered. Adduct formation was proved by Job's plot, H-1 NMR and FT-IR analysis. Probe L showed very low limit of detection (LOD) value of 1.467 nM towards CN-. Probe L was also applied to the CN- detection in real-world water samples by the spike and recovery method. The maximum relative standard deviation (RSD) value was 4.24, indicating this method works successfully. Therefore, probe L could find a potential use in detection of CN- in liquid media.Publication Synthesis of di- and tricationic surfactants and comparison of their activity on oxidation of metal in hcl media(Maik Nauka/interperiodica/springer, 2023-11-02) Öztürk, Serkan; ÖZTÜRK, SERKAN; Gültekin, Zafer; GÜLTEKİN, ZAFER; Akgül, Gülsen; Alper, Mürsel; ALTINÖLÇEK GÜLTEKİN, NURAY; ALPER, MÜRSEL; Fen Edebiyat Fakültesi; Psikoloji BölümüIn this study, two surfactants with the same long chain were synthesized. One shows dicationic and the other tricationic properties. Various spectroscopic methods such as FT-IR, H-1 NMR and C-13 NMR were used to confirm the structures of the synthesized surfactants. The inhibition activities of two synthesized surfactants against mild steel corrosion in 1.0 M HCl solution were determined using the weight loss method. The 24-h corrosion tests on metal coupons immersed in acidic solutions were carried out using different inhibitor concentrations and similar and successful inhibition was obtained for both surfactants. Current density was determined by potentiodynamic polarization at a single inhibitor concentration to compare with the inhibition efficiency results obtained by decrease in weight method. Based on the current density, the inhibition efficiencies of the surfactants were calculated by Tafel extrapolation method. The inhibition efficiency results obtained by both weight loss and Tafel method were close and consistent. According to both methods, the corrosion inhibition of dicationic surfactant was slightly better than that of tricationic surfactant. By determining the critical micelle concentration for the two surfactants, some physicochemical parameters such as surface tensions and free energy of micelle formation at this concentration were calculated and correlated with their corrosion inhibitory activity. Scanning electron microscopy was used to ascertain the surface roughness conditions of metals submerged in an acidic solution, thus visually proving that surfactants protect the metal surface from corrosion.