Browsing by Author "Battal, Ahmet"

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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; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; 0000-0002-9466-1111 ; HNL-5314-2023; AAB-1630-2020
In 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.
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; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; 0000-0002-9466-1111; JCN-8292-2023; AAB-1630-2020
A 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).
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; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; 0000-0002-9466-1111; JCN-8292-2023 ; EDG-8300-2022 ; AAB-1630-2020
4-(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.
High efficiency OLEDs based on anthracene derivatives: The impact of electron donating and withdrawing group on the performance of OLED
(Elsevier, 2016-03) Aydemir, Murat; Haykır, Gülçin; Battal, Ahmet; Jankus, Vygintas; Sugunan, Sunish K.; Dias, Fernando B.; Al-Attar, Hameed; Türksoy, Figen; Monkman, Andrew P.; Tavaslı, Mustafa; Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Kimya Bölümü.; 0000-0002-9466-1111; AAB-1630-2020; 6506308760
New well-defined bulky anthracene derivatives with side groups having electron donating or withdrawing properties 8a-d were synthesized. The compounds contain substituted anthracene as the central core attaching 2-(4-(2-pyridinyl)-phenyl)vinyl and 4-R-phenyl [R:H (a), OMe (b) and CF3 (c), N(Ph)(2) (d)] groups at 9- and 10-positions. The impact of electron donating, withdrawing and neutral groups and their influence on the molecules photophysical, charge transfer (CT), triplet transfer (TT) and triplet-triplet annihilation (TTA) properties has been investigated. Based on the photophysical studies the most promising molecule (8d) has been selected and high efficiency fluorescent OLEDs with EQE at very low current efficiency reaching 7% were obtained. The value at low current density implies a Triplet Fusion (TF) contribution of 45%, very close to the maximum theoretical value of 50% when only the singlet decay channel is open to TTA, however we believe that in this case both TTA and TADF contribute to the triplet harvesting to yield high EQE values, and this mixed triplet harvesting arises through the heterogeneity of the films. At high current density a brightness of 20000 cd/m(2) was achieved and it is assigned partially to the material crystallisation.
Synthesis of novel multifunctional carbazole-based molecules and their thermal, electrochemical and optical properties
(Beilstein-Institut, 2020-05) Battal, Ahmet; Peveler, William J.; Yu, Holly A.; Skabara, Peter J.; Altınölçek, Nuray; Tavaslı, Mustafa; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; 0000-0002-9466-1111; JCN-8292-2023; AAB-1630-2020; 56955836600; 6506308760
Two novel carbazole-based compounds 7a and 7b were synthesised as potential candidates for application in organic electronics. The materials were fully characterised by NMR spectroscopy, mass spectrometry, FTIR, thermogravimetric analysis, differential scanning calorimetry, cyclic voltammetry, and absorption and emission spectroscopy. Compounds 7a and 7b, both of which were amorphous solids, were stable up to 291 degrees C and 307 degrees C, respectively. Compounds 7a and 7b show three distinctive absorption bands: high and mid energy bands due to locally excited (LE) transitions and low energy bands due to intramolecular charge transfer (ICT) transitions. In dichloromethane solutions compounds 7a and 7b gave emission maxima at 561 nm and 482 nm with quantum efficiencies of 5.4% and 97.4% +/- 10%, respectively. At positive potential, compounds 7a and 7b gave two different oxidation peaks, respectively: quasi-reversible at 0.55 V and 0.71 V, and reversible at 0.84 V and 0.99 V. At negative potentials, compounds 7a and 7b only exhibited an irreversible reduction peak at -1.86 V and -1.93 V, respectively.
Yellowish-orange and red emitting quinoline-based iridium(III) complexes: Synthesis, thermal, optical and electrochemical properties and OLED application
(Elsevier Science, 2020-07-06) Battal, Ahmet; Cameron, Joseph; Peveler, William J.; Yu, Holly A.; Skabara, Peter J.; Altınölçek, Nuray; Tavaşlı, Mustafa; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; 0000-0002-9466-1111; CCY-8756-2022; 56955836600; 6506308760
Two novel heteroleptic iridium(III) acetylacetonate (acac) complexes K3a and K3b were synthesised from cyclometallating ligands of 2-(4'-formylphenyl)quinoline lla and 2-(5'-formylphenyl)quinoline 11b. Complexes K3a and K3b were fully characterised by NMR spectroscopy, mass spectrometry and FT-IR. Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) indicate that both complexes were amorphous solids, stable up to 303 degrees C and 313 degrees C, respectively. Complexes K3a and K3b showed strong, high-energy absorption bands ( <400 nm) due to ligand-centred ((LC)-L-1) transitions and weaker, low-energy absorption bands (400 - 600 nm) arising from a mixture of metal-to-ligand charge transfer ((MLCT)-M-1/(MLCT)-M-3) and ligand-centred ((LC)-L-3) transitions. In degassed dichloromethane solutions, complexes K3a and K3b gave yellowish-orange and red phosphorescent emissions at 579 nm and 630 nm, with quantum efficiencies of 99.3 % and 79.3 %, respectively. At positive potential, complexes K3a and K3b exhibited a one-electron reversible oxidation (En) peak at 0.69 V and a quasi-reversible oxidation (ET1/2ox) peak at 0.60 V, respectively, which were assigned to the Ir (III)/Ir(IV) couple. At negative potentials, complexes K3a and K3b exhibited a one-electron irreversible reduction peak at -1.79 V and -1.94 V, respectively. Phosphorescent organic light-emitting diodes (PhOLEDs) were fabricated with a device configuration of ITO/PEDOT:PSS/EML/TPBi/LiF/Al, in which K3a and K3b gave yellowish-orange and red electroluminescence (EL) at 572 nm and 628 nm, respectively. Complex K3a gave the highest luminance of 2773 cd/m(2), current efficiency of 3.3 cd/A, external quantum efficiency of 1.2 % and maximum power efficiency of 1.05 lm/W with a turn-on voltage of 5.0 V (Device A).