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Öğe A New Strategy for Photo-Electrochemical Reduction of Carbon Dioxide Using a Carbazole-BODIPY Based Metal-Free Catalyst(Wiley-V C H Verlag Gmbh, 2024) Özdemir, Mücahit; Uluçay, Sude; Altınışık, Sinem; Köksoy, Baybars; Yalçın, Bahattin; Koyuncu, SermetIn 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.Öğe Direct Photopatterning of BODIPY-Based Small Molecules via Thiol-ene Click Chemistry(John Wiley and Sons Inc, 2023) Özdemir, Mücahit; Altınışık, Sinem; Ömeroğlu, İpek; Köksoy, Baybars; Durmuş, Mahmut; Yalçın, Bahattin; Koyuncu, SermetWe 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.Öğe Light driven photocatalytic hydrogen generation using BODIPY-thiophene-covalent organic polymers(Pergamon-Elsevier Science Ltd, 2025) Turgut, Kübra; Özdemir, Mücahit; Yıldız, Gizem; Yalçın, Bahattin; Koyuncu, Sermet; Köksoy, Baybars; Hatay Patır, İmrenBoron-dipyrromethene (BODIPY) - based dyes have recently garnered attention as sensitizers for photocatalytic hydrogen production. They exhibit high catalytic activity through efficient electron transfer, owing to their unique properties such as high molar absorptivity, adjustable absorption and emission energies, and high fluorescence quantum efficiencies. In this study, the effect of a –OH subunit that can increase hydrophilicity on the photocatalytic hydrogen evolution in BODIPY-thiophene-based covalent organic polymers (COP) was investigated. In the conducted research, COP structures were integrated into BODIPY to enhance their light absorption capabilities, aiming to serve as photocatalysts for energy conversions under simple conditions. In the proposed system, Thiophene-BODIPY-based dyes are integrated into COP structures, where they facilitate electron excitation upon light absorption, thereby playing an effective role in photocatalytic reactions by promoting electron transfer. The photocatalyst, modified with titanium dioxide (TiO2) nanoparticles, exhibited notable performance in enhancing the efficiency of the hydrogen production process, owing to its light absorption capabilities, multifunctional fluorescent properties, and electron-accepting characteristics. The synthesized BODIPY-Th-COP-OH_TiO2 photocatalyst demonstrated higher hydrogen activity compared to BODIPY-Th-COP-CH3_TiO2, attributed to the presence of hydroxyl groups promoted hydrophilic character in the catalyst structure. Therefore, BODIPY-Th-COP-X_TiO2 photocatalysts (X: OH, CH3) utilizing methanol as sacrificial agent yielded hydrogen amounts of 0.197 mmol g−1 h−1 and 0.132 mmol g−1 h−1 for BODIPY-Th-COP-OH_TiO2 and BODIPY-Th-COP-CH3_TiO2 photocatalysts, respectively, under visible light illumination.Öğe Light-Induced Performance Enhancement of Supercapacitors through Thiol-Ene Click Surface Functionalization of Thienothiophene-BODIPY Porous Polymers(American Chemical Soc, 2025) Özdemir, Mücahit; Uluçay, Sude; Sevimli, Esra; Altınışık, Sinem; Köksoy, Baybars; Yalçın, Bahattin; Koyuncu, SermetPhotoassisted 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.Öğe Photophysical and photochemical properties and comparison of tolyl and tosyl coumarin-bearing phthalocyanines(Elsevier, 2023) Kazancıçok, Zehra; Esar Güler, Hatice; Özdemir, Mücahit; Pişkin, Mehmet; Bulut, Mustafa; Yalçın, Bahattin; Salan, ÜmitIn this study, peripheral and non-peripherally substituted Zn(II) phthalocyanine complexes were synthe-sized from 7-hydroxy-3-(p-tolyl)coumarin and 7-hydroxy-3-(p-tosyl)coumarin compounds. The synthe-sized new compounds were characterized using elemental analysis, FT-IR, UV-Vis, Fluorescence 1 HNMR spectroscopy and MALDI-TOF mass spectrometry. All the synthesized phthalocyanine complexes showed good solubility in organic solvents such as acetone, dichloromethane, chloroform, pyridine, and ethyl acetate. Fluorescent quenching behavior was investigated using 1,4-benzoquinone and potassium io-dide as a quencher. The photophysical (fluorescent quantum yields and lifetimes) and photochemical (single oxygen and photodegradation quantum yields) properties of these new phthalocyanines were examined in dimethyl sulfoxide. Phthalocyanine complexes containing 7-hydroxy-3-(p-tolyl)coumarin had higher singlet oxygen quantum yields than phthalocyanine complexes containing 7-hydroxy-3-(p- tosyl)coumarin. Phthalocyanines to which coumarins are peripherally bound were more advantageous than their non-peripherally bound derivatives. As a result of their photophysical and photochemical prop-erties, coumarin-phthalocyanine complexes containing tolyl-/tosyl-groups can be used as photosensitiz-ing candidates in photodynamic therapy and can be developed with targeted modifications.Öğe Symmetrical and Asymmetrical Thiophene-Coumarin-Based Organic Semiconductors(American Chemical Society, 2024) Altınışık, Sinem; Özdemir, Mücahit; Kortun, Arzu; Zorlu, Yunus; Yalçın, Bahattin; Köksoy, Baybars; Koyuncu, SermetOrganic semiconductors are a valuable material class for optoelectronic applications due to their electronic and optical properties. Four new symmetric and asymmetric thiophene-coumarin derivatives were designed and synthesized via Pd-catalyzed Suzuki and Stille Cross-Coupling reactions. Single crystals of all synthesized thiophene-coumarin derivatives were obtained, and π···π interactions were observed among them. The π···π interactions were supported by UV–vis, transmission electron microscopy, and atomic force microscopy analyses. The photophysical and electrochemical properties of the coumarins were investigated and supported by density functional theory studies. Fluorescence quantum yields were recorded between 36 and 66%. Moreover, mega Stokes shifts (175 nm or 8920 cm–1) were observed in these new chromophore dyes. The emission and absorption colors of the thiophene-coumarin compounds differed between their solution and film forms. Electrochemically, the highest occupied molecular orbital levels of the coumarins increased with the 3,4-ethylenedioxythiophene group, leading to a narrowing of the band gap, while the phenyl bridge weakened the donor–acceptor interaction, expanding the band gap.Öğe Synthesis and photovoltaic properties of novel ferrocene-substituted metallophthalocyanines(Royal Society of Chemistry, 2022) Özdemir, Mücahit; Köksoy, Baybars; Kuruca, Halid; Altindal, Ahmet; Durmuş, Mahmut; Koyuncu, Sermet; Yalçin, BahattinIn this paper, a series of new metallophthalocyanines, including ferrocene groups, were designed, synthesized and, characterized, and their photovoltaic properties were investigated as alternative electron-donor materials in bulk heterojunction (BHJ) solar cells. These products were synthesized by a Sonogashira cross-coupling reaction between tetraiodophthalocyanine and ethynyl ferrocene. The newly synthesized phthalocyanines (4-6) were characterized by FT-IR, UV-Vis, H-1 NMR, and MALDI-TOF spectroscopic methods and elemental analysis. The electrochemical characterizations were carried out by cyclic voltammetry as well as differential pulse voltammetry. Density functional theory calculations were realized to prove the charge separation between ferrocene as an electron-donor and the phthalocyanine ring as an acceptor. According to UV-Vis measurements, a 25 nm red-shift was observed for complex 4 compared with complexes 5 and 6. Finally, the photovoltaic performance of these compounds used as an electron-donor moiety in a BHJ device were investigated. A function of different blend ratios was tested by fabricating a series of BHJ devices with the architecture of FTO/PEDOT:PSS/4-6: PCBM blend/Ag with an identical thickness of the active layer. The results indicated that the photovoltaic conversion efficiency of BHJ devices exhibited a strong blend-ratio dependence. The maximum power conversion efficiency was obtained by 5-based devices, as 3.65%, with a blend ratio of 1.5 : 1.0 under standard AM 1.5 illumination.Öğe The Role of Electron-Donating Subunits in Cross-Linked BODIPY Polymer Films(John Wiley and Sons Inc, 2023) Özdemir, Mücahit; Köksoy, Baybars; Yalçın, Bahattin; Koyuncu, SermetA new method for synthesizing cross-linked 4,4-difluoro-4-bora-3a,4a-diaza-s-indacenes (BODIPYs) using a radical-based thiol-ene click reaction is developed. This method is simple, efficient, and cost-effective, and it produces polymers with unique optical, electrochemical, and surface morphology properties. Significant blue shifts in absorption and photoinduced electron transfer in emissions are observed in the cross-linked BODIPY thin films. Cross-linking also leads to the restriction of conjugation, which results in the breakage of the terminal vinyl group, an increase in the oxidation potential, and a slight upshift in the HOMO position. As a result, the electrochemical band gap is widened from 1.88 to 1.94 eV for polymer bearing N,N-dimethylamino-BODIPY and from 1.97 to 2.02 eV for polymer bearing N,N-diphenylamino-BODIPY moieties. Monomer thin films form planar surfaces due to crystallinity, while amorphous cross-linked BODIPY polymers form more rough surfaces. Additionally, photopatterning on the film surface is successfully performed using different patterned masks. This new method for synthesizing cross-linked BODIPYs has the potential to be used in a variety of applications, including organic electronics, bioimaging, and photocatalysis.Öğe Visible Light-Induced Synthesis of Conjugated Poly(phenylene butadiynylene) by a Combination of Halide Abstraction and Coupling Reactions(American Chemical Society, 2023) Nakipoğlu, Büşra; Aydoğan, Cansu; Özdemir, Mücahit; Yağcı, Yusuf; Koyuncu, Sermet; Kıskan, BarışThis study describes a simple and efficient method forsynthesizingconjugated poly(phenylene butadiynylene) (PPB)polymers using photo-inducedradical homocoupling. The approach involves irradiating 1,4-bis(bromoethynyl)benzenewith visible light in the presence of dimanganese decacarbonyl (Mn-2(CO)(10)), which acts as a radical generator by abstractinghalides and promoting subsequent radical coupling reactions. The resultingconjugated PPB exhibited a remarkable red shift, andthe optical band gap decreased from -2.76 to -2.27 eV.A similar effect was observed in the electrochemically measured oxidationpotential; the highest occupied molecular orbital position regressedfrom -6.06 to -5.69 eV. Transmission electron microscopyand atomic force microscopy measurements revealed the self-organizationof the polymers to planar 2D nanorods, and the 2D structures of thepolymers were further supported by density functional theory calculations.Moreover, the surface area of the polymer was found to be 53.61 and30.69 m(2)/g according to Brunauer-Emmett-Tellerand Barrett-Joyner-Halenda methods, respectively.
