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    Multi-response behavior of aminosulfonaphthole system
    (Elsevier Science Bv, 2016) Doğan, Fatih; Kaya, İsmet; Temizkan, Keyser
    Here, we report regioselectively functionalized synthesis, as well as photo physical, electrochemical, and thermal, of a novel water-soluble conjugated polymer. For this purpose, horseradish peroxidase (HRP)-catalyzed polymerization of a multifunctional monomer, 7-amino-4-hydroxy-2-naphthalene sulfonic acid (AHNAPSA) was carried out by using hydrogen peroxide as the oxidant at room temperature for 24 h under air. The structure of poly(7-amino-4-hydroxy-2-naphthalene sulfonic acid), (PAHNAPSA) was identified by using nuclear magnetic resonance, infrared and ultraviolet-visible. Further characterization was performed by means of gel permeation chromatography (GPC), thermogravimetry (TG), differential scanning calorimetry (DSC), cyclic voltammetry (CV), photoluminescence (PL), dynamic light scattering (DLS) and solid state conductivity measurements. The spectral analysis results exhibited functional group selective polymerization of the monomer containing a multi-active center. Solvent effects on the optical, electrochemical and photo physical properties of PAHNAPSA were investigated by using five different solvents. PAHNAPSA presented an irreversible redox characterization at different scan rates. Optical band gap of PAHNAPSA is also found in the range of 3.18 eV to 3.55 eV. The fluorescence measurements were utilized to investigate the photochemical behaviors of PAHNAPSA in selected polar solvents. Accordingly, PAHNAPSA surprisingly presented multicolor emission behavior with relatively high quantum yield in all selected solvents. In addition, PAHNAPSA presented a reversible pH-responsive behavior and also had high selectivity and sensitivity towards chromium ions. Finally, the kinetic parameters associated with the solid state thermal degradation of PAHNAPSA were calculated from isoconversional methods. The TG/DTG analysis showed that PAHNAPSA followed a diffusion controlled degradation mechanism in N-2. (C) 2016 Elsevier B.V. All rights reserved.
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    Öğe
    Regioselectively functionalized synthesis of poly(amino naphthalene disulfonic acid)
    (Elsevier Science Sa, 2016) Doğan, Fatih; Kaya, İsmet; Temizkan, Keyser
    Here, we reported the regioselective formation of poly(amino naphthalene disulfonic acid) (PANDA) nanoparticles by a template-free polymerization process in an aqueous alkaline medium. The NMR, FT-IR, UV-vis, gel permeation chromatography (GPC), thermogravimetry (TG), differential scanning calorimetry (DSC), cyclic voltammetry (CV), photoluminescence (PL), dynamic light scattering (DLS), X-Ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and conductivity techniques were used to investigate the structure characterization in addition to the chemical and physical properties of PANDA polymer-based nanoparticle with molecular weight ca. 14000 Da. Polymer-based nanoparticle showed a reversible redox behavior because of its electroactive nature. PANDA, also, emitted a yellow light while ANDA typically emitted a blue light in DMSO. PANDA displayed an uncommon high photoluminescence quantum efficiency of approximately 30%. The kinetic parameters related to the solid state thermal decomposition of the poly-nanoparticles were calculated from isoconversional methods based on multiple heating rates by TG-DTG/DTA curves. (C) 2016 Elsevier B.V. All rights reserved.
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    Öğe
    Synthesis of soluble poly(azomethine)s containing thiophene and their fluorescence quantum yields
    (Springer, 2020) Temizkan, Keyser; Kaya, İsmet
    In this study, poly(azomethine)s containing thiophene unit and with pyridine, oxygen and sulfur bridges are synthesized via the condensation reaction at the organic medium. The obtained compounds were structurally clarified by Fourier-transform infrared, ultraviolet-visible and nuclear magnetic resonance (H-1, C-13 NMR) spectroscopic techniques. Replies of optic and electronic excitation were getting and utilized by photoluminescence (PL) spectroscopy and cyclic voltammetry techniques. In addition, thermal characteristics were obtained by thermogravimetric/differential thermal analyses and differential scanning calorimetry analysis. Photochromic properties and quantum yields were particularly examined by PL spectroscopy. In particular, P-ThPy compound has multicolor emissions and high quantum yields in DMF and EtOH solvents. It has five colors such as blue (excited at 340, 360, 380, 400, 420, 440 nm), green (460 nm), yellow (480 nm), orange (500 nm) and red (520 nm) emissions in DMF solvent. Additionally, it determined two different colors, blue (320, 340, 360, 380, 400, 420, 440, 460 nm) and yellow (480 nm) emissions in EtOH solvent. The quantum yields of P-ThPy were found as 19.6% and 22.1% and 9.0%, 11.0% in DMF and EtOH solvents, respectively, when excited at 460, 480 nm for DMF and at 420, 460 nm for EtOH.