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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, 2024) 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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    A novel acetylcholinesterase inhibition based colorimetric biosensor for the detection of paraoxon ethyl using CUPRAC reagent as chromogenic oxidant
    (Elsevier B.V., 2024) Ayaz, Selen; Ulucay, Sude; Uzer, Ayşem; Dilgin, Yusuf; Apak, Reşat
    A novel colorimetric biosensor for the sensitive and selective detection of an organophosphate pesticide, paraoxon ethyl (POE), was developed based on its inhibitory effect on the acetylcholine esterase (AChE) enzyme. The bis-neocuproine copper (II) complex ([Cu(Nc)2]2+) known as the CUPRAC reagent, was used as a chromogenic oxidant in the AChE inhibition-based biosensors for the first time. To initiate the biosensor, an enzymatic reaction takes place between AChE and its substrate acetylthiocholine (ATCh). Then, enzymatically produced thiocholine (TCh) reacts with the light blue [Cu(Nc)2]2+ complex, resulting in the oxidation of TCh to its disulfide form. On the other hand, [Cu(Nc)2]2+ reduces to a yellow-orange cuprous complex ([Cu(Nc)2]+) which gives maximum absorbance at 450 nm. However, the absorbance of [Cu(Nc)2]+ proportionally decreased with the addition of POE because the inhibition of AChE by the organophosphate pesticide reduced the amount of TCh that would give a colorimetric reaction with the CUPRAC reagent. Based on this strategy, the linear response range of a colorimetric biosensor was found to be between 0.15 and 1.25 μM with a detection limit of 0.045 μM. The fabricated biosensor enabled the selective determination of POE in the presence of some other pesticides and metal ions. The recovery results between 92% and 104% were obtained from water and soil samples spiked with POE, indicating that the determination of POE in real water and soil samples can be performed with this simple, accurate, sensitive, and low-cost colorimetric biosensor.
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    Black-to-Transmissive Electrochromic Switching PEDOT-co-poly(N-ethylcarbazole) via a Sustainable and Facile In Situ Photo(co)polymerization Method
    (Amer Chemical Soc, 2024) Tabak, Tugberk; Altinisik, Sinem; Ulucay, Sude; Koyuncu, Sermet; Kaya, Kerem
    It is a great challenge to obtain black-to-transmissive switches using one type of polymer. Therefore, the color blending/mixing theory has been previously applied by many research groups to produce black-to-transmissive materials (BTMs) through the (electro)chemical copolymerization of several monomers. However, these (electro)chemical copolymerization methods exhibited numerous drawbacks in terms of sustainability. In this work, for the first time, the synthesis of an electrically conductive (bromide-doped) poly(3,4-ethylenedioxythiophene)-poly(N-ethylcarbazole) (PEDOT-co-PECz) copolymer was demonstrated using an in situ and sustainable photopolymerization technique. Spectrally and microscopically characterized copolymers were then deposited onto ITO/glass using spray coating. The copolymer film demonstrated to switch from a black state (L*: 38.16; a: -0.33; b: -2.89) to a transmissive state (L* = 83, a* = -3, b* = -6) with a contrast of 31.6% Delta T at 650 nm in fast response times (2.28-4.38 s). The results highlight the importance of this advanced method for the sustainable and fast fabrication of smart windows.