Yazar "Altinisik, Sinem" seçeneğine göre listele

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    Huisgen Cycloaddition Reaction of Nitrile Imines With Acyl Phosphonates: Synthesis of Phosphonate Containing 1,3,4-Oxadiazoles and DFT Analysis
    (Wiley, 2025) Polat-Cakir, Sidika; Altinisik, Sinem
    The application of the Huisgen cycloaddition reaction between acyl phosphonates (dipolarophile) and highly reactive intermediate nitrile imines (NI) as a 1,3-dipole in situ generated by the conversion of hydrazonyl chlorides in the presence of a base is reported to synthesize the phosphonate-containing 1,3,4-oxadiazole compounds in 53%-89% yields. Oxadiazole compounds stand out as significant target molecules in drug design and development due to their potential biological activities. Having a phosphonate group in the structure of the 1,3,4-oxadiazole may enhance biological activity be enhanced. We have synthesized 10 new phosphonate-containing oxadiazole compounds that are fully characterized by using spectroscopic analysis. Density Functional Theory (DFT) calculations were carried out to compare the energies of the frontier orbitals of the acyl phosphonates (dipolarophile) and NI (1,3 dipole) to determine the nature of the interaction between the dipolarophile and the 1,3-dipole. The relevant Huisgen cycloaddition reaction proceeds via a normal-electron demand (NED) pathway.
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    Hydrophilic porous organic polymers with fluorene-viologen units for enhanced photocatalytic hydrogen production
    (Elsevier, 2025) Altinisik, Sinem; Yildiz, Gizem; Turgut, Kubra; Yayla, Cansu; Patir, Imren Hatay; Koyuncu, Sermet
    The rising energy demand and environmental concerns have intensified the search for clean energy solutions. Photocatalytic water splitting offers a promising route, yet efficiency remains limited by the need for advanced photocatalysts with enhanced light absorption, charge separation, and water interaction. Porous organic polymers (POPs) are emerging as efficient materials for solar energy conversion due to their ordered conjugated structures. This study explores the impact of a ketone moiety on the hydrophilicity and photocatalytic hydrogen evolution efficiency of fluorene-bridged bicarbazole-viologen-based POPs (POP-MB-TP(DCzFO) and POP-MB-TP (DCzF)). Our results show that POP-MB-TP(DCzF) achieves a hydrogen evolution rate of 3.37 mmol g- 1 h- 1, nearly twice that of POP-MB-TP(DCzFO) (1.72 mmol g- 1 h- 1). This improvement highlights the role of hydrophilicity in charge transport and catalytic efficiency, providing insights for designing highly efficient organic photocatalysts for sustainable hydrogen production.
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    Light-Induced Enhancement of Cross-Linked Viologen-Fluorene Polymer Electrode for High-Performance Supercapacitors
    (Amer Chemical Soc, 2026) Altinisik, Sinem
    Porous organic polymers (POPs) are generally prepared as insoluble powders and coated onto the electrode surface with another polymer binders such as PVDF: HFP during electrode preparation. POP-based electrodes formed through surface cross-linking hold promise for supercapacitor applications. In this study, a new pyridinium-fluorene donor-acceptor monomer (FBP_allyl) was synthesized and cross-linked onto graphene sheet conductive substrates via a thiol-ene click reaction to prepare a photoactive polymer electrode with light-harvesting and charge storage capability. The specific capacitance of the fabricated electrodes at 2.0 A/g was almost doubled under visible light, from 152.7 F/g (dark) to 304.1 F/g (light). In a three-electrode configuration, the electrochemical cell exhibited a power density of over 3000 W/kg, while the energy density increased from 35 to 60 Wh/kg under illumination. Furthermore, the prepared electrode cell showed long-term stability over 10,000 cycles, demonstrating that combining donor-acceptor engineering with thiol-ene cross-coupling is an effective approach for developing photoassisted capacitors with improved electrochemical performance.
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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; Bulut, Mustafa
    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.
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    Photopolymerized PEDOT-coated polydopamine: A Green approach for supercapacitor electrode materials
    (Elsevier, 2025) Ermis, Sena; Tohtayeva, Jahan; Altinisik, Sinem; Ulucay, Sude; Jockusch, Steffen; Kiskan, Baris; Koyuncu, Sermet
    Conjugated conductive polymers (CCPs) are promising electrode materials for next-generation supercapacitors (SCs), yet their scalable and eco-friendly synthesis remains a challenge. Here, we report a light-driven, in-situ polymerization of EDOT onto polydopamine (PDA@PEDOT), offering a sustainable, photoinitiated route for high-performance SC electrodes. Using an organic, environmentally safe photoinitiator and ethanol as a green solvent, this method achieves uniform PEDOT deposition on PDA with minimal energy input. Using a three-electrode method, the resulting PDA@PEDOT electrode exhibits exceptional electrochemical performance, including a high specific capacitance of 275 F g-1 at 1.0 A g-1, an energy density of 34.04 W h kg-1, and excellent adhesion properties. The synergistic non-covalent interactions between PDA's amine, catechol, quinone functionalities and PEDOT are credited to enhance ion transport through the electrode, improving SC efficiency. These exceptional properties, alongside strong adhesion and uniform deposition of PEDOT on PDA, demonstrate the novelty of the advanced photopolymerization approach. Our eco-friendly photopolymerization method paves the way for sustainable, high-performance SC electrode fabrication, bridging the gap between sustainable chemistry and next-generation energy storage.
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    Sequential and Simultaneous Photoinduced Radical and Step- Growth Polymerizations of Carbazole Functional Styrene
    (Amer Chemical Soc, 2022) Celiker, Tugba; Altinisik, Sinem; Vaitusionak, Aliaksei; Kostjuk, Sergei V.; Koyuncu, Sermet; Yagci, Yusuf
    Photoinduced radical and step-growth polymerizations of carbazole functional styrene (vinyl phenyl carbazole, VPC) by sequential and one-pot strategies have been investigated. The obtained polymers were characterized by FTIR, H-1-NMR, GPC, UV-Vis, PL, CV, and BET analyses. The theoretical charge distribution and HOMO-LUMO calculation by DFT were well-matched with those obtained from optical and electrochemical measurements. In the sequential approach, visible light-induced free-radical photopolymerization of VPC by using bisacyl phosphineoxide results in the formation of linear polymers with side-chain carbazole moieties. The resulting polymers exhibit a smooth surface as a consequence of decreasing crystallinity. As evidenced by TEM analysis, the subsequent photoiniated step-growth polymerization of the carbazole groups by using diphenyliodonium hexafluorophosphate (DPI) yields hyperbranched and cross-linked polymers with the microspheres on the surface. In the one-pot approach, concomitant photoinitiated free-radical and step-growth polymerizations by using DPI results in the formation of cross-linked polymers with dispersed distribution. The total nitrogen uptake of VPC-based polymers by using Brunauer-Emmett-Teller (BET) surface area was found to be between about 150 and 190 m(2)/g at 77 K.
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    Tetra-Carbazole based electroactive donor-acceptor dyes: Effect of the phenyl bridging unit on the electrochromic performance
    (Elsevier Sci Ltd, 2022) Doyranli, Ceylan; Altinisik, Sinem; Ozdemir, Mucahit; Koyuncu, Sermet
    In this study, a new Donor-Acceptor-Donor (D-A-D) electroactive molecules (HCQM1 and HCQM2) containing 9H-carbazole and 9-phenyl-9H-carbazole as donor along with quinoxaline (HQ) as acceptor were synthesized and then coated on Indium Tin Oxide/Glass (ITO/Glass) surface by the electrochemical oxidation process. The HOMO-LUMO band gap values obtained by electrochemical oxidation and reduction onsets were calculated as 2.64 and 2.68 eV, respectively. On the other hand, UV-Vis absorption measurements showed that the charge transfer band of HCQM1 was detected at 500 nm with 50 nm red shift upon compared with the HCQM2. According to AFM results, it is seen that the roughness of the poly(HCQM2) film is higher than the poly(HCQM1) film. Finally, the polymer film of HCQM2 showed multi-electrochromic color change (yellow, green, and dark blue) upon the oxidation process. When the electrochromic performance of the HCQM1 and HCQM2 polymer films was compared, it was discovered that the HCQM2 with phenylene spacer unit has better stability and a higher percentage transmittance change (& UDelta;T%) between neutral and oxidized states.
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    Tuning the Electrochromic Properties of Fluorinated Benzochalcogenodiazole Based Donor-Acceptor Polymers
    (Wiley-V C H Verlag Gmbh, 2020) Colak, Betul; Altinisik, Sinem; Koyuncu, Fatma Baycan; Canimkurbey, Betul; Koyuncu, Sermet
    In this study, a series of benzochalcogenodiazole based donor acceptor monomers namely 4,7-bis(4-hexyl-2-thienyl)-2,1,3-benzothiadiazole (TST), 5,6-difluoro-4,7-bis(4-hexyl-2-thienyl)-2,1,3-benzothiadiazole (TST2) and 4,7-bis(4-hexyl-2-thienyl)-2,1,3-benzoselenadiazole (TSeT) were synthesized by Stille reaction and then directly polymerized on to Indium Tin Oxide coated glass (ITO/Glass) surface by electrochemical polymerization process. According to UV-Vis measurements, a 20 nm blue shift was detected at low energy band after fluorination of TST (TST2). Besides, a 40 nm red shift was observed by changing S to Se on the benzochalcogenodiazole moiety (TSeT). Thus, the optical band gaps were varied as 2.32, 2.45 and 2.16 eV for TST, TST2 and TSeT, respectively. According to AFM results, rougher surface was observed in the PTSeT thin film than that of PTST and PTST2. Thin films of electrodeposited polymers onto ITO/glass surface displayed ambipolar multi-electrochromic behavior both anodic and cathodic region. The ambipolar charge distribution was also observed in the theoretical DFT calculations. When the electrochromic performance of the polymer films was compared to each other, it was seen that the PTST2 has a better stability and higher the percentage transmittance change (Delta T%) at near-IR regime between neutral and oxidized states.
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    Viologen-Benzothiadiazole-Based Porous Organic Polymers for High-Performance Photoelectrochemical Supercapacitors
    (Wiley-V C H Verlag Gmbh, 2025) Altinisik, Sinem; Koyuncu, Sermet
    Porous organic polymers (POPs) containing donor-acceptor (D-A) moieties have recently emerged as promising electrode materials for supercapacitors due to their tunable electronic structures, controlled charge transfer capabilities, and high redox activities. In this study, a light-absorbing D-A type POP was prepared using the solvothermal method by combining a benzothiadiazole-carbazole-based donor-acceptor core with viologen-based peripheral groups. The photoelectrochemical H-type cell was constructed with a viologen-based POP photoanode and a reduced graphene oxide (rGO) cathode electrode. The specific capacitance of the supercapacitor increased from 274.8 to 383.4 F/g at 1 A/g under illumination due to the decrease in charge transfer resistance of the electrode upon exposure to light. The constructed photoelectrochemical supercapacitor retained 88% of its capacitance after 10 000 cycles under irradiation and showed an energy density of approximately 80 Wh/kg under the same conditions. These results demonstrate the potential of photo responsive D-A POPs as efficient materials for multifunctional supercapacitors.