Yazar "Altinisik, Sinem" seçeneğine göre listele

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    A New Strategy for Photo-Electrochemical Reduction of Carbon Dioxide Using a Carbazole-BODIPY Based Metal-Free Catalyst
    (Wiley-V C H Verlag Gmbh, 2025) Ozdemir, Mucahit; Ulucay, Sude; Altinisik, Sinem; Koksoy, Baybars; Yalcin, Bahattin; Koyuncu, Sermet
    In this study, a cross-linked boron dipyrromethene (BODIPY) photocatalyst containing a carbazole donor group designed for photoelectrocatalytic carbon dioxide (CO2) reduction is synthesized and characterized. The BODIPY-based system, coated onto a platinum surface, is evaluated for its electrochemical and photocatalytic performance under light illumination. Cyclic voltammetry (CV) and chronoamperometry measurements reveals enhanced photocurrent responses, confirming the catalyst's ability to effectively drive CO2 reduction. Gas chromatography/mass spectrometry (GC-MS) analysis identifies the formation of ethanol (C2H5OH) as a major reaction product, showing that its yield increased with extended reaction times. Additionally, the photocatalyst demonstrates remarkable performance with significantly increasing turnover numbers (TON) and turnover frequencies (TOF) over time, indicating stable and sustained catalytic activity. With a Faradaic efficiency of 34.79% at a potential of -1.15 V, this BODIPY system exhibits both high activity and long-term stability. The combination of efficient electron transfer and visible light absorption by the carbazole-BODIPY donor-acceptor structure positions this system as a highly promising candidate for sustainable CO2 conversion applications.
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    Direct Photopatterning of BODIPY-Based Small Molecules via Thiol-ene Click Chemistry
    (Wiley-V C H Verlag Gmbh, 2023) Ozdemir, Mucahit; Altinisik, Sinem; Omeroglu, Ipek; Koksoy, Baybars; Durmus, Mahmut; Yalcin, Bahattin; Koyuncu, Sermet
    We demonstrate a BODIPY-based small molecule photopatterned surface by thiol-ene click chemistry at room temperature utilizing only 366 nm UV light. The resulting cross-linked polymer exhibits porous surfaces according to AFM and TEM results. A dramatic blue shift occurred in absorption spectra and the photoluminescence was also intensified as a result of crosslinking. Optical and electrochemical results are compatible with the DFT calculations. The obtained results prove that the photopatterned BODIPY-based material can be easily and inexpensively applied in multilayer optoelectronic devices.
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    Electron-Donating and Electron-Withdrawing Subunit Effects on Coumarin-BODIPY Dyads: Optical and Electrochemical Properties and Molecular Interactions
    (Wiley-V C H Verlag Gmbh, 2023) Koksoy, Baybars; Ozdemir, Mucahit; Altinisik, Sinem; Zorlu, Yunus; Yalcin, Bahattin; Durmus, Mahmut; Koyuncu, Sermet
    In this study, a series of coumarin-BODIPY molecules were synthesized using a Sonogashira cross-linking reaction. The effects of electron withdrawing and electron donating moieties on electrochemical and optical properties were supported by results of density functional theory calculations, and energy transfer mechanisms were investigated. The band gap value decreased from 2.0 eV to 1.6 eV due to reversible oxidation of the extra dimethylamino subunit at lower potential. Besides, characteristics of the crystal structures were investigated with single-crystal X-ray diffraction, and crystallinity was supported by differential scanning calorimetry. In addition, when the thin film surface morphologies were examined, it was clearly observed that the N,N-dimethylamino group on the coumarin-BODIPY dyad (B3) formed large-scale domains due to its crystalline behavior. As a result, Forster-type energy transfer was observed for coumarin-BODIPY dyads containing different electron withdrawing and donating subunits.
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    Light-Induced Performance Enhancement of Supercapacitors through Thiol-Ene Click Surface Functionalization of Thienothiophene-BODIPY Porous Polymers
    (Amer Chemical Soc, 2025) Ozdemir, Mucahit; Ulucay, Sude; Sevimli, Esra; Altinisik, Sinem; Koksoy, Baybars; Yalcin, Bahattin; Koyuncu, Sermet
    Photoassisted supercapacitors are emerging as next-generation energy storage devices that synergistically combine light harvesting and electrochemical energy storage. BODIPY-based semiconductors, known for their strong light absorption, tunable electronic properties, and photostability, have recently attracted attention as efficient photoactive components in such systems. This study investigates the potential use of cross-linked thieno[3,2-b]thiophene-BODIPY polymer as an electrode material for photoassisted supercapacitors, prepared through a surface functionalization approach using thiol-ene click chemistry. The polymer exhibited broad-band absorption and a low band gap due to extended conjugation, as confirmed by UV-vis and fluorescence spectroscopy, along with comprehensive optical, electrochemical, and morphological characterization. DFT calculations showed that the HOMO-LUMO energy gap narrows under illumination, indicating improved charge transport. Cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) measurements confirmed that the cross-linked polymer offers high capacitance, low internal resistance, and long cycle stability. In terms of supercapacitor performance, a photoinduced enhancement of up to 50% in specific capacitance was observed under light. At a current density of 1.0 A/g, the specific capacitance increased from 240 F/g in the dark to 362 F/g under illumination. Stability tests conducted over 2000 cycles demonstrated that the supercapacitor retained 90% of its initial capacitance.
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    New metallophthalocyanines including benzylphenoxy groups and investigation of their organic-field effect transistor (OFET) features
    (Elsevier Sci Ltd, 2022) Ozdemir, Mucahit; Altinisik, Sinem; Koksoy, Baybars; Canimkurbey, Betul; Koyuncu, Sermet; Durmus, Mahmut; Yalcin, Bahattin
    In this study, metal and metal-free novel phthalocyanines containing peripheral and non-peripheral tetra 2-ben-zylphenoxy groups were synthesized. The compounds were characterized by UV-Vis, FT-IR, H-1 NMR, and MALDI-TOF mass spectrometry as well as elemental analysis. These new phthalocyanines exhibited excellent solubility in most organic solvents, and their redox behavior was investigated in different solvents such as dimethyl sulfoxide (DMSO) and dichloromethane (DCM). The redox behavior of the peripheral and non-peripheral phthalocyanine compounds 1a -c and 2a -c was determined by cyclic voltammetry and in situ spec-troelectrochemistry. According to organic field-effect transistors (OFETs) measurements, the peripheral and non-peripheral phthalocyanine-cobalt complexes which have higher mobility than others were utilized top-gate bottom-contact OFETs fabrication. The output characteristics of the device show that its mobility is approximately 5 x 10(-2) cm(2)/Vs with p-type accumulation.