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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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    Influence of bulky peripheral substituents on subphthalocyanine derivatives: Implications for photocatalytic and photoelectrochemical hydrogen production
    (Elsevier Sci Ltd, 2024) Dogan, Sifa; Guentay, Buket; Demircioglu, Perihan Kuebra; Akyrldrz, Yigit Osman; Koca, Ayse; Aslan, Emre; Kurtay, Guelbin
    A series of novel subphthalocyanine (SubPc) derivatives with bulky electron-donating substituents were synthesized for visible light-induced photocatalytic and photoelectrochemical hydrogen production. SubPc derivatives were decorated with bulky thiophenoxy (coded SubPc 1-2) and phenoxy (coded SubPc 3-4) substituents to compare the influence of the nature of the peripheral bulky substituents on the photophysical and photocatalytic activity of SubPc. The highest photocatalytic performance was obtained from SubPc 4, having diphenyl phenoxy substituents with an H-2 production rate of 7.233 mmol g(-1)h(-1). The photocatalytic hydrogen evolution activities of all SubPc sensitized TiO2 photocatalysts enhanced approximately four times in the presence of Pt co-catalyst. The photocatalysts showed remarkable long-term stability and reproducibility of H-2 evolution over 24-hour irradiation. SubPc 4-based photocatalytic system reached a considerable catalytic activity with the H-2 production of 16.022 mmol g(-1) and a turnover number (TON) value of 34,089 for 24 h irradiation. Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) studies were carried out to better understand the photocatalytic abilities of SubPc derivatives and develop a symbiotic connection with experimental investigations. The results highlight the importance of peripheral substituents in modifying electron density, dipole moment, and HOMO-LUMO energy levels and improving SubPc derivative lightharvesting performance. The presence of 2,6-diisopropyl on SubPc derivatives (SubPc 2 and 4) caused a significant change in the properties, resulting in favourable electron transport characteristics and, therefore, improving photocatalytic performance. Furthermore, the incorporation of TiO2, as shown in SubPc 1@TiO2 and SubPc 2@TiO2, resulted in a modest reduction in chemical hardness, implying increased charge transfer inside the molecule and, as a consequence, enhancing its efficacy as a sensitizer. These theoretical discoveries provide a solid foundation for the customized design and optimization of SubPc derivatives for effective photocatalytic applications.
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    Solar light-driven hydrogen evolution by co-catalyst-free subphthalocyanine-sensitized photocatalysts
    (Royal Soc Chemistry, 2024) Dogan, Sifa; Guntay, Buket; Demircioglu, Perihan Kubra; Akyildiz, Yigit Osman; Aydin, Hasan; Aslan, Emre; Can, Mustafa
    Subphthalocyanines (SubPcs) have emerged as promising organic dyes for the development of efficient artificial photosynthetic devices, offering intense absorption in the visible region along with excellent charge transport properties. In this study, four novel SubPc derivatives containing carboxylic acid and various peripheral substituents were synthesized as a panchromatic photosensitizer to prepare an efficient and stable TiO2-based photocatalytic system for co-catalyst-free photocatalytic hydrogen evolution. To compare the influence of the nature of the peripheral substituents on photocatalytic activity, SubPc derivatives (coded as SubPc 1-4) were decorated with substituents having different electron-donating capabilities, such as alkyl thio, benzodioxin, amine, and iodo units, respectively. Photocatalytic activities were examined in the presence of TEOA as a sacrificial agent under irradiation with lambda > 400 nm without co-catalyst loading. SubPc 1/TiO2 shows the best photocatalytic activity among the SubPc-sensitized photocatalysts, with a hydrogen evolution rate of 0.176 mmol h(-1). While the activity of all four SubPc-based photocatalysts increased significantly after 24 h irradiation, notably, SubPc 1/TiO2 exhibited remarkable catalytic activity, achieving a hydrogen evolution rate of 6.017 mmol with a high turnover number (TON) value of 12 279 for hydrogen production. This study highlights the potential of SubPc-based sensitizers for co-catalyst-free photocatalytic H-2 production and offers valuable insights into the impact of peripheral units in SubPc/TiO2-based photocatalytic systems.
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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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    Subphthalocyanines for Visible-Light-Driven Hydrogen Evolution: Tuning Photocatalytic Performance with Molecular Design
    (Amer Chemical Soc, 2023) Guntay, Buket; Dogan, Sifa; Killi, Askin; Genc Acar, Eminegul; Demircioglu, Perihan Kubra; Aslan, Emre; Kurtay, Gulbin
    In this work, a series of subphthalocyanines (SubPcs)with a carboxylicacid anchoring group at the axial position were used as photosensitizersof TiO2 for photocatalytic hydrogen evolution from waterunder visible light irradiation. SubPc derivatives with various peripheralsubstituents were successfully prepared to systematically investigatethe dependence of photocatalytic performance on electron-donatingunits (i.e., bisthiophene or thioether) at the peripheral positionof the SubPcs. SubPc 2/TiO2/Pt shows the best photocatalyticactivity among the three dye-sensitized photocatalysts, with a hydrogenevolution rate of 1.104 mmol center dot g(-1)center dot h(-1). After 24 h irradiation, SubPc 2/TiO2/Ptachieved a remarkable catalytic activity for the production of H-2 (19.96 mmol center dot g(-1)) with a TON valueof 40 734 and a high STH efficiency of 2.1%. Density functionaltheory (DFT) and time-dependent DFT (TD-DFT) approaches were usedto elucidate further structural and electrical properties, includingthe interaction patterns of tailored SubPcs. It is worth noting thatthe theoretical computations exhibit good conformity with the empiricaldata. The predicted fluctuations in photocatalytic activity detectedin SubPc systems were shown to be closely associated with frontiermolecular orbital (FMO) characteristics, noncovalent interaction (NCI)patterns, and the electron-donating nature of the fragments locatedat the peripheral positions.
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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.