Yazar "Yuzer, A. Celil" seçeneğine göre listele

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    Field Effect versus Driving Force: Charge Generation in Small-Molecule Organic Solar Cells
    (Wiley-V C H Verlag Gmbh, 2020) Nikolis, Vasileios C.; Dong, Yifan; Kublitski, Jonas; Benduhn, Johannes; Zheng, Xijia; Huang, Chengye; Yuzer, A. Celil
    Efficient charge generation in organic semiconductors usually requires an interface with an energetic gradient between an electron donor and an electron acceptor in order to dissociate the photogenerated excitons. However, single-component organic solar cells based on chloroboron subnaphthalocyanine (SubNc) have been reported to provide considerable photocurrents despite the absence of an energy gradient at the interface with an acceptor. In this work, it is shown that this is not due to direct free carrier generation upon illumination of SubNc, but due to a field-assisted exciton dissociation mechanism specific to the device configuration. Subsequently, the implications of this effect in bilayer organic solar cells with SubNc as the donor are demonstrated, showing that the external and internal quantum efficiencies in such cells are independent of the donor-acceptor interface energetics. This previously unexplored mechanism results in efficient photocurrent generation even though the driving force is minimized and the open-circuit voltage is maximized.
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    Imidazole substituted Zinc(ii) phthalocyanines for co-catalyst-free photoelectrochemical and photocatalytic hydrogen evolution: influence of the anchoring group
    (Royal Soc Chemistry, 2021) Yuzer, A. Celil; Genc, Eminegul; Kurtay, Gulbin; Yanalak, Gizem; Aslan, Emre; Harputlu, Ersan; Ocakoglu, Kasim
    Novel zinc phthalocyanine derivatives, ZnPc-1 and ZnPc-2, consisting of one and four imidazole units, respectively, have been synthesized and utilized as panchromatic photosensitizers for photocatalytic and photoelectrochemical H-2 evolution. The effect of the imidazole-anchoring group on the photocatalytic H-2 production has been compared with ZnPc-3, which possesses a carboxylic acid unit as the anchoring group. ZnPc-1/TiO2 shows the best photoactivity with the highest H-2 evolution rate of 0.4006 mmol g(-1) h(-1), which is much higher than that of ZnPc-2/TiO2 and ZnPc-3/TiO2 (0.3319 mmol g(-1) h(-1) and 0.3555 mmol g(-1) h(-1), respectively). After 20 h of irradiation, ZnPc-1 produces an H-2 production rate of 3.4187 mmol g(-1) with a turnover number (TON) of 14863 and a solar-to-hydrogen energy (STH) conversion efficiency of 1.03%, without using a co-catalyst.
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    Improving the Photocatalytic Hydrogen Generation Using Nonaggregated Zinc Phthalocyanines
    (Amer Chemical Soc, 2021) Acar, Eminegul Genc; Yuzer, A. Celil; Kurtay, Gulbin; Yanalak, Gizem; Harputlu, Ersan; Aslan, Emre; Ocakoglu, Kasim
    In comparison to traditional solar cells, the dye-sensitized photocatalytic system is one of the most appealing artificial photosynthesis mechanisms due to its low cost and straightforward fabrication. Herein, the photoelectrochemical and photocatalytic hydrogen evolution reactions of Zn-based phthalocyanine (Pc) derivatives, abbreviated as ZnPc-1 and ZnPc-2, were primarily studied in the presence of TEOA sacrificial electron donor. To this aim, the PC activities of ZnPc-1/TiO2 and ZnPc-2/TiO2 photocatalysts were investigated in the absence and presence of a cocatalyst. For the first hour, the amount of hydrogen generated by ZnPc derivatives (ZnPc-1/TiO2 and ZnPc-2/TiO2) was determined to be 1.221 and 0.864 mmol g(-1) h(-1), respectively. Additionally, the solar-to-hydrogen conversion efficiencies of ZnPc-1/TiO2 and ZnPc-2/TiO2 were ascertained to be 3.15% and 2.22%, respectively. Interestingly, STH efficiencies of photocatalysts were increased about 4-fold in the presence of a cocatalyst. Consequently, to elucidate the structural properties of ZnPc-1 and ZnPc-2, density functional theory (DFT) and time-dependent DFT studies were also conducted, and it was discovered that noncovalent interactions and steric hindrance effects on ZnPc-2 are tightly related to the experimentally determined PC activity differences between ZnPc-1 and ZnPc-2.
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    Solar-light-driven photocatalytic hydrogen evolution by push-pull thiophenoxy-substituted zinc phthalocyanines
    (World Scientific Publ Co Pte Ltd, 2023) Acar, Eminegul Genc; Ince, Tuncay; Yuzer, A. Celil; Yanalak, Gizem; Gecgel, Cihan; Aslan, Emre; Ince, Mine
    Two zinc phthalocyanine derivatives (ZnPc 1 and 2) carrying bulky 2,6-diisopropylthiophenoxy peripheral substituents have been synthesized and their performances as photosensitizers in photochemical hydrogen production evaluated. To examine the influence of the spacer on the performance of ZnPc 1 and 2, the carboxyl group has been linked to the macrocycle ring either directly or via the phenyl ring, respectively. The photocatalytic activities of ZnPcs (ZnPc 1 and ZnPc 2) as sensitizers of TiO(2 )for hydrogen production were investigated in the presence of Pt. ZnPc 1 and ZnPc 2 sensitized TiO(2 )produced 0.687 mmolg(-1)h(-1) and 0.436 mmol g(-1)h(-1) hydrogens, which also reached 3.986 and 2.091 mmolg(-1) after 8h illumination, respectively, under visible light (>= 420 nm) irradiation. In addition, STH efficiencies of ZnPc 1/TiO2 and ZnPc 2/TiO2 were determined as 1.77% and 1.12%, respectively. ZnPc 1/TiO2 exhibited 1.9-fold more photocatalytic hydrogen amount than ZnPc 2/TiO2, and the hydrogen evolution performance of the photocatalyst in the presence of Pt enhanced to 3.021 mmol g(-1)h(-1) and 0.911mmol g(-1)h(-1) for ZnPc 1 and ZnPc 2, respectively.
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    Solution-processed small-molecule organic solar cells based on non-aggregated zinc phthalocyanine derivatives: A comparative experimental and theoretical study
    (Elsevier Sci Ltd, 2021) Yuzer, A. Celil; Kurtay, Gulbin; Ince, Tuncay; Yurtdas, Semih; Harputlu, Ersan; Ocakoglu, Kasim; Gullu, Mustafa
    A series of non-aggregated zinc phthalocyanine derivatives containing either bulky thiophenol or phenol substituents were synthesized as a novel donor component for bulk heterojunction (BHJ) solar cell applications. The molecular structure and photophysical properties of ZnPc derivatives were investigated by combined experimental and theoretical studies using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. In order to evaluate the physical properties of ZnPcs in the solvent environment, we applied the conductor-like polarizable continuum model (CPCM). Within this scope, light-harvesting efficiency (LHE), excited-state lifetime (?), maximum absorption wavelengths (?max), oscillator strength (f) and hyperpolarizability (? tensors) were calculated both in vacuum and chloroform (? = 4.9) medium. Furthermore, divergent types of global descriptors such as EHOMO, ELUMO, and bandgap (Egap) energies, ionization potential (I), electron affinity (A), hardness (?), and electrophilicity index (?) were also calculated. Our computational findings revealed that the linker heteroatoms [sulfur for the ZnPc (1?2); oxygen for the ZnPc (3?4) including the substituent type (isopropyl for the ZnPc (2?4), and phenyl for the ZnPc (1?3] severely affected the photophysical properties of the dyes. In relation, theoretical results are in good accordance with our experimental observations. Finally, ZnPc derivatives were used as a donor component and PC61BM as an acceptor material in BHJ solar cells, displaying a maximum power conversion efficiency of 0.8%. Compared with ZnPcs 1?2, ZnPc 3?4 based cells showed an inferior photovoltaic performance. These results are promising and should encourage further studies on BHJ solar cells using near-infrared absorbing and non-aggregated ZnPcs.
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    Subphthatocyanine-sensitized TiO2 photocatatyst for photoetectrochemical and photocatatytic hydrogen evolution
    (Royal Soc Chemistry, 2020) Yuzer, A. Celil; Genc, Eminegul; Harputlu, Ersan; Yanalak, Gizem; Aslan, Emre; Ocakoglu, Kasim; Patir, Imren Hatay
    A series of SubPcs comprising a carboxylic acid anchoring group at the peripheral (SubPcs 1, 2) or axial position (SubPc 3) were synthesized and used as sensitizers for photocatatytic H-2 production, for the first time. SubPc 3/TiO2 shows the best photocatatytic activity with a hydrogen evolution rate of 1396 mu mol h(-1), which is much higher than that of SubPcs 1 and 2 (771 and 658 mu mol g(-1) respectively). This work clearly shows that considering their optical and redox properties, SubPcs are promising candidates for light-driven water splitting systems.
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    Superior photo-induced antibacterial/antibiofilm activities of ZnPcs/TiO2 and computational simulation studies
    (Royal Soc Chemistry, 2023) Ozcan, Tugce; cekceoglu, Ilknur Aksoy; Al-Khafaji, Khattab; Oner, Erkan; Yuzer, A. Celil; Yalin, Serap; Aslan, Emre
    Bacteria can form biofilms on any surface, which causes biofilm-associated infections and bacterial resistance to antibiotics. Thus, it is important to design new-generation non-chemotherapeutic nanoagents for effective antibacterial and antibiofilm strategies. Herein, the effects of the anchoring groups, which are imidazole and carboxylic acid, of zinc phthalocyanines (ZnPcs) sensitized TiO2 on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were investigated under light-emitting diode (LED) irradiation. The photocatalytic antibacterial activities of ZnPc-1/TiO2 and ZnPc-2/TiO2 on the bacterial strains were examined by monitoring the optical density value at 600 nm (OD600 nm). Glutathione (GSH) oxidation assay was used to measure the reactive oxygen species (ROS) generation activity of the compounds. Bacterial damages were imaged by scanning electron microscopy (SEM). According to our photocatalytic antibacterial mechanism, photogenerated electrons are transferred from Pcs to TiO2 and then react with O-2, thus creating ROS, which causes damage to bacterial membrane, protein and biofilm destruction as well. Further, computational simulation analysis was used to show the interaction patterns of ZnPc-1 and ZnPc-2 with penicillin binding protein 2a (PBP2a) of S. aureus and FimH lectin protein (PDB:4XO8) of E. coli to elucidate the dark molecular antibacterial mechanism of the compounds. The obtained results from computational studies showed that ZnPc-2 binds firmly through bonds with the 1MWT protein from S. aureus. On the other hand, ZnPc-1 binds firmly through bonds with the 4XO8 protein from E. coli. From combining experimental and computational results, we can conclude that this strategy can be applied to different types of bacterial infections.
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    The effect of central metal in phthalocyanine for photocatalytic hydrogen evolution via artificial photosynthesis
    (Pergamon-Elsevier Science Ltd, 2020) Genc, Emineguel; Yuzer, A. Celil; Yanalak, Gizem; Harputlu, Ersan; Aslan, Emre; Ocakoglu, Kasim; Ince, Mine
    Phthalocyanines (Pcs) are promising sensitizers in photocatalytic hydrogen evolution reaction from water splitting owing to the unique absorption properties and familiar sensitizers for light phase of photosynthesis. In this paper, two phthalocyanines (Pcs) bearing tetra carboxylic acid at the peripheral position with Zn and Co atoms as a central metal have been prepared in order to investigate the effect of the central metal atoms on the performance of photocatalytic hydrogen evolution from water splitting for mimicking photosynthesis. The photoelectrochemical and photocatalytic hydrogen evolution ex-periments have been carried out by using Pcs sensitized TiO2 (TiO2, ZnPc/TiO2 and CoPc/TiO2) and Pt co catalyst in the presence of triethanolamine (TEOA) as a sacrificial electron donor under visible light. The hydrogen production rate of ZnPc/TiO2 and CoPc/TiO2 have been determined as the 1146 and 1051 mmolg(-1)h(-1), respectively. The hydrogen evolution rates of ZnPc/TiO2 and CoPc/TiO2 have been enhanced by in situ photodeposited Pt, which are reached by 3448 and 3328 mmolg(-1)h(-1) for the ZnPc/TiO2/Pt and CoPc/TiO2/Pt, respectively. These results have been established that ZnPc sensitized TiO2 shows more photocatalytic activity than CoPc sensitized TiO2 in the both absence and presence of Pt. These obtained results can be attributed to the spectral response of Pc sensitizers. (c) 2020 Elsevier Ltd. All rights reserved.
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    The influence of central metal in phthalocyanine for photodynamic therapy of glioblastoma
    (World Scientific Publ Co Pte Ltd, 2023) Oral, Ayca Tuncel; Yuzer, A. Celil; Ozel, Derya; Ince, Mine; Yurt, Fatma
    Glioblastoma multiforme (GBM) is an aggressive and fatal brain tumor that tends to occur in older adults and has several subtypes. The fact that the mechanisms of initiation and progression of glioblastoma are not yet known is an obstacle to the treatment of the disease. For this reason, studies have been carried out in recent years to develop new therapeutic approaches. Photodynamic therapy (PDT) is a procedure that has been approved and is considered safe in most clinical trials. With the help of a photosensitizer (PS), tumor growth regression is promoted, aiming to prolong the survival of patients with glioma progression. It is extremely important to conduct studies focused on the development, application, and biodistribution of possible candidates for these photosensitizing drugs. Phthalocyanines (Pcs) are good photosensitizers for this purpose. Here, we describe an approach to the application of photodynamic therapy with metal-phthalocyanines [zinc-phthalocyanine (ZnPc) and cobalt-phthalocyanine (CoPc)] and their carboxylic acid derivatives in U87-MG cell lines. For the phototoxicity study, percent viability values were calculated using the MTT test. The results showed that cell death was effectively induced in U87-MG cells. In our study, the phthalocyanines applied in the in vitro treatment of glioblastoma cell lines with PDT have shown high toxicity and the treatment has been successful. Our findings highlight the potential of ZnPc-COOH and CoPc-COOH with their carboxylic acid derivatives as biological material for biomedical applications in the treatment of glioblastoma cells.