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Öğe Comparative study on oxidative and enzyme catalyzed oxidative polymerization of aminophenol compound containing dihalogen(Springer, 2021) Kaya, İsmet; Karacan Yeldir, ElifProperties of polymers were obtained by enzyme catalyzed oxidative polymerization varies according to oxidative polymerization products and thus polymeric materials with diferent properties are obtained. In this study, polymerization of 4-amino2,6-dichlorophenol (ADCP), an aminophenol compound containing dihalogen, was carried out by two diferent methods and the two methods were compared with each other. One of the methods was oxidative polymerization in the presence of hydrogen peroxide with heating, and the other was enzyme-catalyzed oxidative polymerization that took place at room temperature in the presence of Horse Radish Peroxidase (HRP) enzyme and hydrogen peroxide. The structural characterization of the products obtained as a result of oxidative polymerization (PADCP-O) and as a result of enzyme catalyzed oxidative polymerization (PADCP-E) was performed by 1 H-NMR, 13C-NMR, FT-IR, UV–Vis spectroscopy methods. The molecular masses of PADCP-O and PADCP-E were analyzed by GPC and the average molecular mass of PADCP-E was found to be higher than that of PADCP-O. Thermal properties were examined by TGA and it was determined that the thermal stability of the obtained polymers was higher than that of the monomer. Electrochemical and optical properties were determined by CV and UV–Vis spectroscopy methods, respectively. Electrochemical and optical band gap values were calculated as 1.61 and 1.33 eV, and 1.88 and 1.83 eV for PADCP-O and PADCP-E, respectively. In addition, it was observed that PADCP-O emitted green in UV light, while PADCP-E emitted red in DMSO. Surface properties and morphology of polymers were analyzed by SEM and it was observed that PADCP-O obtained by oxidative polymerization had a spongy structure, but the enzymatic polymerization product PADCP-E had a uniformly dispersed nanoparticle structure.Öğe Doku mühendisliği uygulamaları için doğal antibakteriyel içeren biyopolimer iskele sistemlerin hazırlanması(Çanakkale Onsekiz Mart Üniversitesi, Lisansüstü Eğitim Enstitüsü, 2018) Karacan Yeldir, Elif; Oral, AyhanBu tez çalışması kapsamında doku mühendisliği uygulamalarında kullanılmak üzere, doğal antibakteriyel maddeler içeren biyopolimer iskele sistemleri hazırlanmıştır. Doğal polimerlerden olan Kitosan'ın asidik ortamdaki çözünürlüğünden faydalanılarak Kitosan küreler hazırlanmış ve bu küreler içerisine ayrı ayrı doğal antibakteriyel maddeler olan Fenil etil alkol ve Sinnamaldehit ilave edilmiştir. Devamında ise elektropüskürtme yöntemi kullanılarak Kitosan nanoküreler hazırlanmış ve hem çözelti hem de yöntem parametreleri değiştirilerek nanokürelerin morfolojileri incelenmiştir. Ayrıca elektropüskürtme yöntemi ile Kitosan nanoküreler doğal bir antibakteriyel madde varlığında da hazırlanarak bu maddenin morfoloji üzerine etkileri de araştırılmıştır.Elektroeğirme yöntemi ile kitosan nanolif ve doğal antibakteriyel madde içeren kitosan lifler elde edilmiştir. Doğal antibakteriyel maddelerden biri olan Linalool'ün termal radikalik ve fotopolimerizasyon yöntemleri ile polimerizasyonu gerçekleştirimiş ve 1H-NMR spektrumları incelenmiştir. Kaprolakton monomeri kullanılarak α-Lipoik asit ve Sitranellol varlığında ve başlatıcı olarak Kalay Oktanoat ile Poli(ε-kaprolakton) makromerleri elde edilmiş ve karakterizasyonu yapılmıştır.Öğe Fluorescent Oligomeric Nanoparticle from Diaminopyridine Compound Via Enzyme-Catalyzed Oxidation(Springer/Plenum Publishers, 2023) Karacan Yeldir, ElifAn oligomeric nanoparticle was obtained through an enzyme-catalyzed oxidation reaction using Horse Radish Peroxidase (HRP) with the 2,3-diaminopyridine (DAP) compound as the starting material. The structural characterizations of the synthesized oligomeric nanoparticles [[oligo(DAP)](Enz)] were performed with H-1-NMR and FT-IR. The surface features were determined by scanning electron microscopy. The optical properties were determined by UV-Vis and fluorescence spectra. It was found that the obtained oligomeric nanoparticles had a different fluorescent character with 15.90% quantum yield from the monomer and emitted green color at 485 nm when excited with light at a wavelength of 420 nm. The electrochemical band gap of the oligomeric nanoparticles, whose electrochemical character was investigated by cyclic voltammetry, was calculated as 2.09 eV. The thermal stability of the oligomeric material was determined from the mass loss against increasing temperature. The monomer exhibited greater thermal stability in comparison to the polymer, both in terms of the temperature at which the maximum mass loss occurred and the residual amount after heating concluded.Öğe Investigation of electrochemical, optical, and thermal properties via oligomerization of aminophenol monomer containing halogen and nitro groups using two distinct oxidants(Elsevier, 2023) Karacan Yeldir, Elif; Kolcu, Feyza; Kaya, İsmetIn this study, two different oligomers of 2-amino-4-chloro-5-nitrophenol (ACNP) with incorporated halogen atom and nitro groups were synthesized by oxidative oligomerization method using two different oxidants, namely H2O2 and ammonium persulfate (APS). Structural characterizations of the obtained products were elucidated by 1H NMR, 13C NMR, FT-IR, UV-Vis spectroscopy methods. The molecular masses of the oligomers were deter-mined through the utilization of Gel Permeation Chromatography (GPC). The analysis revealed that the Mw values of the oligomers synthesized via the oxidative oligomerization method using H2O2 and APS, denoted as OACNP-1 and OACNP-2 were 4150 Da and 2800 Da, respectively. Using the UV-vis spectrophotometer, the optical band gaps were calculated as 2.64 eV, 1.95 eV and 2.14 eV for ACNP, OACNP-1 and OACNP-2, respectively. Thermal properties of the oligomers were investigated using Thermal Gravimetric Analysis-Differential Thermal Analysis (TGA-DTA) and Differential Scanning Calorimetry (DSC). The results demon-strated that OACNP-1 exhibited significantly higher thermal stability when compared to both the monomer and OACNP-2. In addition, Fluorescence Spectroscopic analysis of the oligomers revealed that OACNP-1 emitted blue light at 440 nm when excited with light of a wavelength of 370 nm, exhibiting fluorescent characteristics. Furthermore, the surface properties and morphologies of the oligomers were analyzed with the help of Scanning Electron Microscopy (SEM), revealing a flower-like structure for the oxidative oligomerization product, OACNP-1, in the presence of H2O2. In course of a change in the oxidant, the oligomer, OACNP-2, had rough and spongy surface morphology with some pores.Öğe Ni(II), Zn(II), and Fe(III) complexes derived from novel unsymmetrical salen-type ligands: preparation, characterization and some properties(Taylor & Francis Ltd, 2022) Dilmen Portakal, Eylem; Kaya, Yeliz; Demirayak, Emire; Karacan Yeldir, Elif; Ercağ, Ayşe; Kaya, İsmetBy using a half-salen ligand (HL) and substituted salicylaldehydes, new unsymmetrical salen-type ligands (H2L1, H2L2, and H2L3) and their Ni(II), Zn(II) and Fe(III) complexes were synthesized. The compounds were characterized based on elemental analysis, IR, H-1 NMR, X-ray diffraction (for HL), spectroscopy, mass spectrometry, magnetic moment, molar conductance measurements, and thermal analysis (TGA). The unsymmetrical salen ligands, during complexation, are attached to the metal by two imine nitrogen atoms and two phenolic oxygen atoms in all complexes; in the Fe(III) complexes, the fifth coordination is completed by chloride. Square planar geometry or distorted square planar geometry for [NiL1-3], [ZnL1-3], and square pyramidal geometry for [FeL1-3Cl] are proposed. Conductance measurements suggest non-electrolytic nature of the metal complexes. Thermogravimetric analysis showed that the complexes exhibit higher stability than the ligands. The electrochemical properties of the compounds were studied by cyclic voltammetry. HOMO-LUMO energy levels and electrochemical band gaps (E '(g)) were calculated. The solid state electrical conductivity of the iodine-doped compounds was measured and their semiconductor properties were determined. In addition, fluorescence properties of ligands and Zn(II) complexes were investigated.Öğe P(2-VP) supported Ru(II) material as catalyst for H2 production from the methanolysis of NaBH4(Taylor & Francis Inc, 2020) Tercan, Melek; Karacan Yeldir, Elif; Dayan, Osman; Oral, AyhanExisting energy resources are not sufficient to meet the energy needs of the increasing world population so the need for clean and renewable energy systems is increasing day after day. Hydrogen is a good alternative energy source because of its clean by-products and high energy capacity. Studies on hydrogen storage systems that provide instant hydrogen production in the literature are of great interest. In this study, poly-2-vinylpyridine (p(2-VP)) polymer was prepared by photopolymerization method and reacted with 2,6-bis(2-benzimidazolyl)pyridine ligand containing Ru(II) complex to give p(2-VP) supported Ru(II) material. The synthesized Ru(II) complex was characterized by FT-IR, UV-Vis and H-1-NMR spectroscopic techniques. Also the p(2-VP) polymer was characterized by FT-IR spectroscopy. The obtained p(2-VP) supported Ru(II) material was used as catalyst in hydrogen generation from NaBH4 metanolysis reaction and the reaction kinetic was investigated.Öğe Polyurethanes derived from triazole-based monomers and their application as fluorescent probe for Zn2+(Pergamon-Elsevier Science Ltd, 2024) Kaya, İsmet; Karacan Yeldir, Elif; Kolcu, Feyza; Niğiz, SimgePolyurethanes are one of the most encountered polymer classes in both industry and scientific research, with their tremendous physical and chemical properties, as well as numerous advantages such as a wide range of raw materials, the ratio of groups to be used during polymerization and adjustable mechanical properties. In this study, four distinct polyurethanes were synthesized using toluene diisocyanate (TDI) and hexamethylenediisocyanate (HMDI) derived from Schiff bases formed by reacting 3,5-diamino-1,2,4-triazole (DAT) and 4 different aldehydes (2-hydroxybenzaldehyde, 4-hydroxybenzaldehyde, 2-hydroxy napthaldehyde, o-vanillin). The structural characterizations of the synthesized Schiff bases and polyurethanes were elucidated using H-1-C-13 NMR and FT-IR, thermal stability was assessed via TGA, molecular weights of the polymers were determined using GPC, electrochemical properties were evaluated by CV, and optical properties were examined using UV-Vis and fluorescence spectrophotometry. The molecular weights of polyurethanes ranged from 4500 to 10300 Da. TGA analysis of the synthesized polyurethanes demonstrated significant thermal stability, maintaining integrity up to 310 degrees C. The band gap energy (E'(g)) values of polyurethanes were found to range from 2.30 to 2.51 eV, which is lower than that of their corresponding monomers, exhibiting semiconductor properties. It was determined that DATSA-PU, one of the synthesized polyurethanes, exhibited potential as a turn-on fluorescent sensor for Zn2+ ion with a LOD value of 2.03 x 10(-7) M.Öğe Schiff bases and oligomers derived from trifluoromethylaniline-based monomers: Thermal, optical, electrochemical properties and applications as fluorescent probes for Sn2+(Elsevier, 2025) Karacan Yeldir, Elif; Kaya, İsmet; Tutluel, OğuzhanWithin the scope of the study, three different Schiff bases were synthesized from 3,5-bis(trifluoromethyl)aniline, a halogen-containing aniline derivative, with three different aldehydes, 3-hydroxy-4-methoxy-benzaldehyde, salicylaldehyde and 2-hydroxy-1-naphthaldehyde. These three synthesized Schiff bases were evaluated as monomers and oxidatively polymerized in the presence of sodium hypochlorite, a strong oxidant. The structural properties of these three monomers and three polymers were elucidated with the help of UV-Vis, FT-IR, 1 H NMR, 13C NMR spectra. Their molecular weights were determined by gel permeation chromatography (GPC) and it was determined that the macromolecules obtained as a result of the oxidation reaction were in the oligomer order. In order to investigate their electrochemical properties, cyclic voltammetry (CV) was used to find their oxidationreduction potentials. The HOMO-LUMO potentials and electrochemical band gap values of the synthesized Schiff bases and oligomers were calculated. Thermal stabilities of the monomers and oligomers were determined by thermogravimetric-differantial thermal analysis (TG-DTA). It was determined that the thermal stabilities of the obtained oligomers were higher than those of the Schiff bases. The glass transition temperature (Tg) and surface morphologies of oligomers were determined from DSC and SEM measurements, respectively. Their optical properties were examined by UV-Vis and fluorescence spectra. It was found that 1-(((3,5-bis(trifluoromethyl) phenyl)imino)methyl) naphthalene-2-ol (TFMHN), one of the Schiff bases, has a turn-on fluorescence sensor property with increasing fluorescence emission intensity in the presence of Sn2+ among a series of metal ions and can be used as a selective and sensitive fluorescence probe for Sn2+ with a limit of dedection (LOD) value of 7.14 x 10- 8 M.Öğe Synthesis and characterization of a pyrene-based Schiff base and its oligomer: Investigation of fluorescent Cr3+ probe(Elsevier, 2022) Karacan Yeldir, Elif; Erdener, Diğdem; Kaya, İsmetIn this study, a unique Schiff base (SP) was synthesized from 1-aminopyrine (1-AP) and salicylaldehyde (SA) compounds. The obtained oligomer of this Schiff base was carried out by the oxidative polymerization method. The structural characterizations of 2-((pyren-1-yl-imino)methyl)phenol (SP) and oligo-2-((pyren-1-yl-imino)methyl)phenol (OSP) by FT-IR, H-1 NMR and C-13 NMR measurements, electrochemical properties by cyclic voltammetry (CV); optical properties by UV/Vis studies and photoluminescence (PL) spectrophotometry; thermal stability were performed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The molecular weight of the obtained oligomer was determined using gel permeation chromatography (GPC). Accordingly, Mn and Mw values of OSP were found to be 2800 and 3150 Da, respectively. The imine bond provided the structures with high thermal stability, and the maximum mass loss temperatures (T-max) of SP and OSP were found to be 350(0) and 343 degrees C, respectively. PL study showed that SP could be used as a Cr3+ sensor among a series of metals. The results revealed that the limit of detection (LOD) value of SP was 1.03 x 10(-)(9) M and was not affected by other ions in the environment.Öğe Synthesis of pyrene and pyrrole-appended fluorescent turn-off sensor toward Cr(VI) detection: Chemical oxidative and electrochemical polymerization of carboxamide(Elsevier B.V., 2024) Kaya, İsmet; Karacan Yeldir, Elif; Kolcu, Feyza; Erdener, DiğdemA carboxylic amide compound containing pyrrole and pyrene groups, referred to as PP, was synthesized and characterized for its structural, optical, and electrochemical properties. Upon excitation with 320 nm light, PP displayed blue emission at 387 nm, which was found to be quenched due to chelate formation in the presence of Cr(VI). Conducted competition experiments involving chloride salts of Ag+, Al3+, Cd2+, Co2+, Cr3+, Fe3+, Hg2+, K+, Mn2+, Ni2+, Pb2+, Sn2+, and Zn2+ demonstrated the notable selectivity of compound PP towards Cr(VI) ions. This selectivity was evidenced by a pronounced turn-off fluorescent effect, attributed to a chelation-enhanced quenching (CHEQ) mechanism by the formation of 1:2 chelation between Cr(VI) and the ligand PP. Moreover, addition of EDTA to PP– Cr(VI) chelation recovered the fluorescence offering receptor PP as a reversible sensor. The PP probe demonstrated remarkable selectivity in detection Cr(VI) ions among various metallic ions, displaying a limit of detection (LOD) value of 0.106 µM. Chemical oxidative and electropolymerization methods were employed to synthesize two distinct polymers, namely Poly(PP)-O and Poly(PP)-E, respectively. The electropolymerization of PP was carried out in 0.1 M TBAF6P serving as a supporting electrolyte solution, while oxidative polymerization was conducted in the presence of FeCl3. Mass average molecular weight of the oxidative polymerization product was 5200 Da, as determined by GPC analysis. Thermal characterization was performed via TG-DTA-DTG curves. The electropolymerization product of PP coated on the ITO surface was further characterized by SEM.Öğe Synthesis, characterization and investigation of fluorescent Sn2+ probe potential of pyrene-derived monomer and its oligo(azomethine) compound(Pergamon-Elsevier Science Ltd, 2022) Karacan Yeldir, Elif; Kaya, İsmetA monomer (2-methoxy-6-((pyren-1-yl-imino)methyl)phenol, VP) was synthesized by the Schiff base reaction of o-vanillin (VA) and 1-aminopyrene (AP), and an oligomer (oligo-2-methoxy-6-((pyren-1-yl-imino)methyl) phenol, OVP) was synthesized from this monomer via oxidative polycondensation reaction. The structural characterization of the obtained monomer and oligomer by FT-IR, H-1 NMR and C-13 NMR; electrochemical properties with cyclic voltammetry (CV); optical properties with UV-Vis and photoluminescence (PL) spectroscopy; thermal stability with thermogravimetric analysis (TGA); and the molecular weight of the oligomer were determined by gel permeation chromatography (GPC). From the fluorescence titration, VP was found to be sensitive to Sn2+ out of a range of metal ions. When the VP solution, to which 1 equivalent amount of Sn2+ was added, was excited with 320 nm light, it was observed that it emits bright blue color at 445 nm. It was found that VP, whose limit of detection (LOD) was calculated as 4.24 nM for Sn2+, had a sensitive and selective fluorescence sensor potential. In addition, it was found that the obtained oligo[2-methoxy-6-((pyren-1-yl-imino)methyl) phenol] (OVP) had a molecular mass of 3450 Da and showed fluorescent properties. The maximum emission of the OVP excited with 380 nm light was observed at 443 nm, with green emission.
