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Öğe A comprehensive investigation of PtNPs/PEI N-GQDs nanocomposite: DFT modeling, anticancer activity, and biosensing applications(Springer, 2025) Altınok Güneş, Buket; Kırlangıç, Ömer Faruk; Kılıç, Murat; Ketenoğlu, Didem; Aslan, Ayşenur; Kabaş, Sultan Yağmur; Kabaş, Afşar; Kaya, İsmet; Yıldız, MustafaThis research focuses on the synthesis and characterization of a novel nanocomposite, PtNPs/PEI N-GQDs, utilizing FTIR, UV-Vis, SEM, TEM, XPS, and XRD techniques. The study investigates the cytotoxic, apoptotic, and antiangiogenic effects of the nanocomposite on OVCAR-3 cells, aiming to understand the interplay between nanomaterials and cancer. Additionally, the electrochemical properties of PtNPs/PEI N-GQDs-modified glassy carbon electrodes (GCE) are explored, emphasizing analyses of HOMO-LUMO energy levels and band gap energy. Density Functional Theory (DFT) analysis results further support these findings by providing insights into the electronic structure and energetics of the nanocomposite. The nanocomposite exhibits promising electrochemical behavior, demonstrating high capacitance and sensitivity in glucose detection through cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Selectivity towards glucose among interfering bioanalytes is highlighted, showcasing potential applications in tumor monitoring and diagnosis. Furthermore, the nanocomposite displays significant toxicity against cancer cells, inducing apoptosis and cell cycle arrest. Antiangiogenic effects are also observed, suggesting potential therapeutic benefits. Overall, these findings underscore the multifunctional properties of the synthesized nanocomposite, offering insights into its potential for cancer therapy and biosensor applications for glucose detection in bodily fluids.Öğe Application of a novel anthracene derivative polymer for sensitive voltammetric determination of chloramphenicol in pharmaceutical and food samples(Pergamon-Elsevier Science Ltd, 2025) Karakaya, Serkan; Kaya, İsmet; Kolcu, Feyza; Dilgin, YusufThe application of new polymers for the preparation of modified electrodes is an interesting research area, which is highly significant in the electrochemical antibiotic drug sensors for food safety and environmental sides. Herein, we successfully report the synthesis of a new anthracene-based monomer (N1, N4-bis(anthracene-9-ylmethylene)-2,5-dichlorobenzene-1,4-diamine (ADCA) and Poly(ADCA) modified carbon-based electrode has been used in sensitive and selective differential pulse voltammetric determination of chloramphenicol (CPNL) for the first time. In this platform, the proposed monomer was successfully electro-polymerized onto a cheap, lowcost, and disposable pencil graphite electrode (PGE). The cyclic and differential pulse voltammetric experiments proved that the polymer-modified electrode Poly(ADCA)/PGE) has great electrocatalytic efficiency on the reduction of CPNL. The proposed platform shows a comparable performance in terms of wide linear ranges (2.0-100 and 100-1000 mu M), a low detection limit (0.55 mu M) and high sensitivity (11405 mu A mM- 1 cm- 2) by differential pulse voltammetry (DPV). Additionally, the Poly(ADCA)/PGE exhibited high selectivity and antiinterference facilities for the CPNL. The fabricated sensor showed a promising potential for the determination of CPNL in food (honey, and milk), bottled water, and pharmaceutical (eye ointment) samples with acceptable accuracies and precisions.Öğe Synthesis and characterization of fluorescent and thermally stable poly (azomethine-ether)s: Optical and morphological properties(Elsevier Sci Ltd, 2025) Tezel, Ruhiye Nilay; Kaya, İsmetIn this work, we described the synthesis and characterization of dialdehyde monomers and poly(azomethineether)s based on them. In the first stage, aromatic bridged dialdehyde monomers were synthesized using 2,4Bis(chloromethyl)-1,3,5-trimethylbenzenedihalide with three different aldehydes (4-hydroxybenzaldehyde, 3methoxy-4-hydroxybenzaldehyde, and 3-ethoxy-4-hydroxybenzaldehyde). Subsequently, corresponding poly (azomethine-ether) derivatives were synthesized through the polycondensation reaction of synthesized dialdehyde monomers with o-toluidine and o-dianisidine diamine compounds. The structures of the obtained dialdehyde and poly(azomethine-ether)s were confirmed by FT-IR, UV-Vis and NMR measurements. The physicochemical properties of the as-prepared poly(azomethine-ether)s have been confirmed through X-ray diffraction (X-RD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDX) spectroscopic techniques. In FT-IR, -CH--N- peak around at 1625 cm-1 attributed to the successful conversion of dialdehydes and diamines into poly(azomethine-ether). The semicrystalline nature of the poly (azomethine-ether)s was shown through the X-RD diffractometer. The optical band gaps were found to be in the range of 2.80-2.92 eV, as measured by UV/Vis analysis. These poly(azomethine-ether)s exhibit direct band gap values in the blue/violet region of visible light, which creates opportunities for future studies related to daylight optoelectronic devices. Additionally, thermal behavior was analyzed using TGA and DSC, revealing that the materials are highly stable and rigid.Öğe Assessing the Aromatic and Quality Components of a Novel Peach Genotype ('Sırrı') Grafted onto Various Rootstocks in the Lapseki Area(MDPI, 2025) Gür, Engin; Gündoğdu, Mehmet Ali; Yılmaz, Neşe; Şeker, MuratThis study examines how various rootstocks affect the pomological, biochemical, and aroma contents of the local ‘Sırrı’ peach genotype grown in the Lapseki region of Türkiye. The research focused on peach trees grafted onto three distinct rootstocks: ‘Seedling’, ‘GF-677’ (P. persica × P. amygdalus), and ‘Rootpac-R’ (P. cerasifera × P. amygdalus). The results showed that peaches from the ‘Seedling’ and ‘GF-677’ rootstocks had larger sizes, greater weights, and brighter colors compared to those from ‘Rootpac-R’. Furthermore, the rootstocks impacted essential quality factors such as soluble solid content, firmness, fruit–flesh ratio, titratable acidity, and total phenolic content levels. The analysis of volatile compounds indicated that aldehydes (which varied from 67.02% to 63.74%), lactones (which changed from 9.14% to 7.99%), and esters (which changed from 12.51% to 11.92%) were the major aroma types in ‘Sırrı’ peaches, with the ‘GF-677’ rootstock exhibiting amplified fruity and sweet aromas due to increased lactone levels. Principal Component Analysis (PCA) revealed the significant effects of rootstocks on both pomological and biochemical characteristics, with ‘Seedling’ showing elevated biophenol levels and ‘GF-677’ contributing to a firmer texture. These findings underscore the importance of rootstock choice in enhancing fruit quality and aroma, indicating that the ‘Sırrı’ genotype is highly suitable for commercial production and future breeding efforts.Öğe Cyber security policies in Türkiye(Nova Science Publishers, Inc., 2024) Avaner, Tekin; Fedai, RecepIn this study, activities carried out for information security in the world and in Türkiye within the framework of information security policy will be discussed. The importance of information security policy has increased even more after cyber-attacks around the world. In this context, the study will include various cyber-attacks, and the measures taken against cybersecurity attacks will be analyzed through an information security policy. The ENISA reports prepared within the framework of the European Union's cyber security policy will be included, and the actors and their activities involved in the construction process of Türkiye's national information security policy will be evaluated. The cyber-attacks experienced in Türkiye will also be touched upon, and the mechanisms developed, official policy documents, and the activities of the actors will be analyzed. The main problem encountered in this context will be the various difficulties in the construction of the national information security policy. The solution to the problem is to focus on which mechanisms the state, which is at the center of the information security policy process, has developed structurally and functionally. In this regard, elements of the management process come to the fore. An information security management system consists of steps such as planning, implementation, control, and taking precautions. © 2025 Nova Science Publishers, Inc.Öğe Reducing respiration rate and increasing chemical stability of mulberry fruits by using postharvest putrescine and melatonin(BioMed Central Ltd, 2025) Eyduran, Şadiye Peral; Çolak, Ayşen Melda; Kuru Berk, Selma; Sakaldaş, Mustafa; Şen, Fatih; Gündoğdu, MuttalipBackground: Plant growth regulators have been widely used to extend the cold storage period of fruits and preserve quality. These phytohormones help mulberry fruit in maintaining its postharvest quality and soft texture, prevent from spoiling during cold. For this purpose, mulberry fruit were stored in cold for 5, 10 and 15 day (0.5 °C and 90% RH) and the impacts of melatonin (1.0 mM) and putrescine (1.0 mM) on quality parameters, phenolic compounds (gallic, protocatechuic, catechin, syringic, p-coumaric, chlorogenic, o-coumaric, ferulic, phloridzin, rutin and quercetin) and organic acids (malic, citric, succinic, oxalic, tartaric, fumaric and ascorbic) were investigated. Results: The combined application of putrescine and melatonin maintained the weight loss (4.35%), decay rate (9.48%) and 29.89% lower respiration rate (6.07 mg CO2 kg− 1 h− 1) in mulberry fruits stored for 15 d as compared to the control. Phenolic compounds (especially rutin) and organic acids were found to be more affected by melatonin and putrescine applications compared to other findings in this study. However, melatonin treatment is more effective in maintaining the level of organic acids and phenolic compounds in mulberry fruit during storage than the putrescine. It was determined that soluble solids content, weight loss, decay rate and pH values had a positive relationship with each other. Also, it was also seen that phenolic compounds and organic acids had a linear relationship. Conclusion: The combined application of melatonin and putrescine was found more effective in maintaining the quality parameters of mulberry fruits during cold storage. © The Author(s) 2025.Öğe Air quality suitability map of Çanakkale urban area (CBS based): ımportance of green spaces(Springer Nature, 2025) Alkan, YavuzÇanakkale is a city with increasing population linked to uncontrolled internal and external migration due to its historical structure and geopolitical situation. Developments in the physical and social structure of the city kept the design of a suspension bridge, which was considered necessary to be built across the Çanakkale Straits (Dardanelles) since the 1990s, alive until 1917. The traffic, industrialization, uncontrolled housing and inadequate environmental planning expected with the opening of the 1915 Çanakkale Bridge, with construction beginning in 2017 and planned for completion in 2022, have recently led to Çanakkale being investigated in terms of air pollution, especially. In this study, emerging as unique at this point, the atmospheric component potential was researched within the scope of 4 counties in Çanakkale province. Air quality maps were obtained for Çanakkale by analyzing the atmospheric component (CO, SO2, NO2, NOX and particulate matter) amounts for July and August of 2021 with GIS modelling. According to the suitability mapping, the Central, Lapseki and Çan regions, with nearly 653.41 km2 area, had suitable air quality, while Biga region with 1043.8 km2 area was not suitable. In conclusion, the study includes strategy development, action plans and recommendations like tax implementations and green space planning for priority preservation and optimization of air quality with the aim of sustainable urban development. © The Author(s) under exclusive licence to Iranian Society of Environmentalists (IRSEN) and Science and Research Branch, Islamic Azad University 2024.Öğe Preparation of composite hydrogels containing fly ash as low-cost adsorbent material and its use in dye adsorption(Springer Science and Business Media Deutschland GmbH, 2022) Önder, Alper; Ilgın, Pınar; Özay, Hava; Özay, ÖzgürAbstract: Recycling industrial wastes is necessary for the economy and the environment. Additionally, it is important to develop high-efficiency adsorbents to prevent severe water pollution caused by wastewater containing dye agents. Here, poly(2-acrylamido-2-methylpropane sulfonic acid)-fly ash composite hydrogel was synthesized with a variety of fly ash proportions with the radical polymerization method. The synthesized composite hydrogel was used for adsorption of methylene blue and methyl orange dyes from water containing dye agents. A variety of parameters such as initial dye concentration, solution pH, anion effects, temperature, contact time and adsorbent amount were investigated for optimization of the adsorption process. The poly(2-acrylamido-2-methylpropane sulfonic acid)-fly ash composite hydrogel was determined to be an effective adsorbent to remove both the cationic dye methylene blue (1438.68 mg g−1) and the anionic dye methyl orange (646.54 mg g−1). Experimental adsorption data were assessed with a variety of isotherm and kinetic models. It was determined that the adsorption of both dye molecules abided by the pseudo-second-order kinetic model. The thermodynamic parameters were determined as ΔH° = − 15.77 ± 5.22 kJ mol−1, ΔS = − 45.05 ± 16.42 J mol−1 K−1 and ΔG° < 0 for MB, ΔH° = − 20.13 ± 4.83 kJ mol−1, ΔS = − 72.87 ± 15.20 J mol−1 K−1 and ΔG° > 0 for MO. In conclusion, a material was synthesized that can be used as a single adsorbent composite material for both anionic and cationic dyes. In addition to the perfect adsorption capacity of this material, it offers reusability and a broad area of application for a variety of dye agents.Öğe Poly(azomethine-epoxy-ether) containing phenyl and etoxy moieties:synthesis, characterization and fluorescence property (vol 72, pg 2821, 2018)(Springer International Publishing Ag, 2020) Kolcu, Feyza; Kaya, İsmet[Anstract Not Available]Öğe Synthesis and characterization of conjugated polyphenols derived from azomethine formation containing terephtaldehyde via oxidative polycondensation(Taylor & Francis Inc, 2016) Kolcu, Feyza; Kaya, İsmetPreparation of conjugated aromatic polyimines, containing phenols in the backbone and side group substitutions, has been successfully achieved by a chemical oxidative polycondensation of a series of Schiff bases using NaOCl as the oxidant at optimum reaction temperature of 90 degrees C. The molecular structures of synthesized compounds were verified by the FT-IR, UV-Vis, H-1-NMR and C-13-NMR techniques. Using thermogravimetric analysis-differential thermal analysis (TG-DTA) and size exclusion chromatography (SEC), the molecular weight distribution parameters and the characterization of all compounds could be specified. The initial degradation temperatures of the polymers were found in the range of 170-271 degrees C. DSC analyses of the polyazomethines (PAMs) were carried out to assign the glass transition temperatures (T-g). UV-Vis measurements gave information about the optical (E-g) band gaps. Fluorescence measurements were carried out to obtain the maximum PL intensities. The spectral analysis outcome signified a blue and a green light emission behavior when irradiated at different wavelengths. Cyclic Voltammetry (CV) was an effective method to explore the HOMO and LUMO energy levels and electrochemical (E-g') band gaps of the polymers. The HOMO energy levels of the synthesized polyimines were lower than those of the monomers indicating the more conjugated structures of the polymers. Four-point collinear probe was used to determine the electrical conductivities of both doped and undoped states of the synthesized polymers with respect to doping time with iodine. The morphological properties of the polymers were illustrated using Scanning Electron Microscopy (SEM) images at different amplifications.Öğe Polymerization of Chrysoidine with chemical and enzymatic oxidative preference: Synthesis, characterization, and spectroscopic study(Wiley, 2018) Kaya, İsmet; Kolcu, FeyzaChrysoidine (CHRY) is a type of azo-dye extensively used in industry. This study delineates 2 routes as enzymatically and oxidatively polycondensation of chrysoidine for the syntheses of poly (chry-enz) and poly (chry-ox), respectively. The molecular structures of enzymatically and oxidatively polymerized chrysoidine were described by the FT-IR, UV-Vis, H-1-NMR, and C-13-NMR techniques. The molecular structures were obtained to be different as in the cyclization process of the enzymatic polymerization. Solvatochromic behavior in selected polar solvents on the optical properties of poly (chry-ox) were studied. Further characterization was implemented by fluorescence (PL), electrochemical, thermogravimetric (TG-DTA), cyclic voltammetry (CV), and differential scanning calorimetry (DSC) measurements. The number of average molecular weight of poly(chry-ox) was found to be higher than that of poly(chry-enz). Photoluminescence (PL) measurements enlightened the response of poly (chry-ox) with intense light emissions upon a bicolor irradiation by Ultra-Violet and visible light. CV technique was utilized to make a comment about HOMO-LUMO energy levels and electrochemical (Eg') band gaps of the polymers. Optical and electrochemical band gaps of poly (chry-enz) were lower than those of poly (chry-ox), proving the successful synthesis of -conjugated structure of poly (chry-enz). To further make comments about the features of the polymers, scanning electron microscopy (SEM) images were exemplified to study the surface forms of the polymers. Surface morphology of poly (chry-enz) was seen as agglomerates of grains toward the out-of-plane direction. As the polymerization method was changed, the morphology was transformed into a flat-smooth surface present with visible holes for poly (chry-ox).Öğe Synthesis, characterization and photovoltaic studies of oligo(acriflavine) via chemical oxidative polymerization(Royal Soc Chemistry, 2017) Kolcu, Feyza; Kaya, İsmetThe present work reports a simple and inexpensive way for the synthesis of a novel water-soluble conjugated oligo(acriflavine) (OAC). Oligo(acriflavine) was synthesized via chemical oxidative polycondensation by H2O2 (30%) as the oxidant at an optimum reaction temperature of 110 degrees C without use of an additional external template. The chemical structure of the synthesized compound was confirmed by FT-IR, UV-Vis, H-1-NMR and C-13-NMR techniques. Further characterization was employed using, photophysical, electrochemical, photovoltaic thermogravimetric-differential thermal analysis (TG-DTA), fluorescence (PL), cyclic voltammetry (CV) and differential scanning calorimetry (DSC) measurements. The number average molecular weight of the oligomer was found to be 4950 Da with a polydispersity index of 1.18. Photoluminescence (PL) properties of the synthesized materials were determined in solution form. The solvent effect on the optical properties of OAC was studied in selected solvents. The spectral analysis displayed a bicolor emission behavior when OAC solution was irradiated at different wavelengths. The HOMO-LUMO energy levels and electrochemical (E-g') band gap values of OAC were determined by CV measurement. Optical and electrochemical band gaps of OAC with more conjugated structure were lower than for AC. XRD analysis signified that the oligomer was in a semicrystalline form. To further study the morphologic properties of the OAC, Scanning Electron Microscopy (SEM) images were illustrated at different amplifications. It was demonstrated that the structure of OAC was essentially a ladder oligomer with phenazine rings. The best performing photovoltaic cell, based on OAC reached a J(sc) of 0.14 mA cm(-2), a V-oc of 0.37 V, and a FF of 0.50, giving a power conversion efficiency (%eta) of 0.027% under AM 1.5 irradiation (100 mW cm(-2)).Öğe Carbazole-based Schiff base: A sensitive fluorescent ‘turn-on’ chemosensor for recognition of Al(III) ions in aqueous-alcohol media(Elsevier, 2022) Kolcu, Feyza; Kaya, İsmetCarbazole-based Schiff base chemosensor was synthesized in one-pot synthesis using 2hydroxy-1-naphtaldehyde for fluorescent sensing of Al3+ ions. Characterization of the ligand (L) was revealed through spectroscopic and physicochemical techniques. The fluorescence emission responses of L to various metal ions and anions were investigated. The chelation was studied by UV-vis, 1H NMR, LC-MS/MS, fluorescence titration and Job's plot analysis. Bathochromic shift resulted from charge transfer from L to electrophilic Al3+ ion was observed in the chelation of L with Al3+. The potentiality of L to be a distinguished probe to detect Al3+ ions was due to a chelation enhanced fluorescence (CHEF) effect, concomitant with noticeable fluorescent enhancement. A significant fluorescence enhancement at 533 nm was observed in ethanol-water (1:1, v/v) solution upon addition of Al3+ along with a distinct color change from yellow to white. Non-fluorescent ligand exposed highly sensitive turn-on fluorescent sensor behavior for selectively sensing Al3+ ions via 1:1 (ligand:metal) stoichiometry. The ligand's specificity in the existence of other tested metal ions and anions indicated no observation in color change. The ligand-Al3+ complex formation was reversible upon addition of chelating agent EDTA. The ligand interacted with Al3+ ions with an association constant of Ka = 5 x 104 M-1. The limit of detection (LOD) was found to be 2.59 x 10-7 M. The synthesized Schiff base could efficiently detect Al3+ ions as a fluorescent sensor. (c) 2022 Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).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 A study of the chemical and the enzyme-catalyzed oxidative polymerization of aromatic diamine bearing chlor substituents, pursuant to structural, thermal and photophysical properties(Pergamon-Elsevier Science Ltd, 2020) Kolcu, Feyza; Kaya, İsmet2,5-Dichloro-p-phenylenediamine (ClPDA) is a member of aromatic diamines. This descriptive study sought the oxidative polymerization of ClPDA with hydrogen peroxide using the enzyme-catalyzed and the chemical oxidative ways for the syntheses of P-ClPDA-E and P-ClPDA-O, respectively. Neutral ClPDA was easily oxidized to the polymers composed of ortho-coupled constitutional moieties with lower optical and electrochemical band gaps than those of ClPDA using two polymerization routes. The elucidation of molecular structures obtained from the enzyme-catalyzed and the chemical oxidative polymerization of ClPDA were carried out by the FT-IR, UV-Vis, H-1 NMR and C-13 NMR techniques, concluded with the ladder-type and the perrnigraniline-type polymer formation as a result of two different polymerization processes. Solvent effects in selected polar solvents on the optical properties of P-ClPDA-E and P-ClPDA-O were also analyzed. Thermal and electrochemical properties of the products were fulfilled using TG-DTA-DSC and cyclic voltammetry (CV) techniques, respectively. The number of average molecular weight of P-ClPDA-E was found to be higher than that of P-ClPDA-O. The degradation of ladder-type structure of P-ClPDA-E with higher M-w value started at higher temperatures compared to P-ClPDA-O, which was composed of benzenoid and quinoid units. In response to the excitation of UV light, only P-ClPDA-E radiated blue light with high intensity and a quantum yield of 23% in DMF depending on photoluminescence measurement. Scanning Electron Microscopy (SEM) views set a precedent for the agglomerates of particles. The enzyme-catalyzed oxidation of ClPDA resulted in the formation of nanospheres of PClPDA-E. In course of a change in the polymerization method, the morphology of the chemical oxidative polymerized ClPDA (P-ClPDA-O) was seen spongy with some pores.Öğe Synthesis and characterization of fluorescent polyphenols anchored Schiff bases via oxidative polycondensation(De Gruyter Poland Sp Zoo, 2018) Kaya, İsmet; Kolcu, Feyza; Satılmış, Sabriye; Yazıcıoğlu, ZeynepA series of polyimines, bearing phenolic groups were successfully synthesized in aqueous alkaline solution via chemical oxidative polycondensation. Polymeric Schiff bases were synthesized by condensation of 2,4-dihydroxybenzaldehyde and 3-hydroxy-4-metoxybenzaldehyde with 2-aminophenol and 3-aminophenol. The molecular structures of the synthesized Schiff bases and their corresponding polymers were studied by FT-IR, UV-Vis, 1H-NMR and C-13-NMR spectroscopic methods. Thermal stability of the imine polymers was evidenced by their initial degradation temperatures found in the range of 170 degrees C to 271 degrees C without any sign of melting. The results of UV-Vis and cyclic voltammetry (CV) measurements were coherent with the optical E-g and the electrochemical E'g band gaps of the polyimines which were lower than those of their corresponding Schiff bases. Fluorescence spectral analysis of P4 (Schiff base polymer P4 derived from 3-aminophenol and 3-hydroxy-4-methoxybenzaldehyde) revealed a bicolor emission with blue and green light. Electrical conductivity of the synthesized imine polymers was measured by four-point probe technique. P4 showed the highest electrical conductivity as a result of iodine vapor contact time. Morphology characterization of the synthesized polyimines was carried out using a scanning electron microscope SEM at different magnifications. The study revealed that P4 is a promising candidate for both blue and green light emitters which could be used in the production of photovoltaic materials and solar cells.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 A Schiff base based on triphenylamine and thiophene moieties as a fluorescent sensor for Cr (III) ions: Synthesis, characterization and fluorescent applications(Elsevier Science Sa, 2020) Kolcu, Feyza; Erdener, Diğdem; Kaya, İsmetA Schiff base fluorescent sensor was designed for selective detection of Cr3+ ions in aqueous solution. The procedure for the study was fulfilled in three steps which comprised the synthesis of 4-nitro-triphenylamine (TPA-NO2), 4-amino-triphenylamine (TPA-NH2) and Schiff base (TPA-Th) using 2,2′-bithiophene-5-carboxaldehyde, respectively. Structural characterization of the purely synthesized compounds was acquired by using UV–Vis, FT-IR, 1H NMR and 13C NMR analyses. Their electrochemical, thermal, and the optical sensor properties for metal ions were enlightened by cyclic voltammetry (CV), thermal-TG-DTA and photoluminescence (PL) techniques, respectively. Non-fluorescent TPA-Th displayed a fluorescence enhancement after chelation with Cr3+ ions with high selectivity and overall emission change of 59-fold at an excitation wavelength of 320 nm. The limit of detection (LOD) value was as low as 1.5 × 10−6 M for Cr3+ ions, accompanied by an association constant (Ka) of 2.8 × 104 M−1. TPA-Th was beneficial for the design and development of metal-complexed fluorescent sensor and light emitting devices.Öğe Poly(azomethine-epoxy-ether) containing phenyl and etoxy moieties: synthesis, characterization and fluorescence property(Springer International Publishing Ag, 2018) Kolcu, Feyza; Kaya, İsmetThe design and synthesis of poly(azomethine-epoxy-ether) (PAZ-EP) containing epoxide moiety was described. The purpose of the research was the improvement of poly(azomethine-ether) containing epoxide by introduction of Schiff base moiety. PAZ-EP was synthesized using epichlorohydrin (EP). The structure of the Schiff base (SB) and PAZ-EP were verified by FT-IR, H-1-NMR, C-13-NMR and UV-Vis spectroscopic analyses. Further characterization was employed using photophysical, electrochemical and fluorescence (PL) measurements. Application of TGA and differential scanning calorimetry analyses revealed thermal stability and thus propose a thermal processibility, which makes them potential materials for many contemporary practices. The number of average molecular weight of polymer with a polydispersity index of 1.14 was found to be 6750 Da using a gel permeation chromatography instrument. The highest occupied-lowest unoccupied energy levels and electrochemical () band gap values of PAZ-EP were determined by cyclic voltammetry (CV) measurement. Scanning electron microscopy (SEM) images were illustrated at different magnifications to study the morphologic property of PAZ-EP.Öğe Synthesis, characterization, optical, and electrochemical properties of thermal stable novel poly(azomethine-ether)s(Taylor & Francis Ltd, 2014) Kaya, İsmet; Avcı, Ali; Kolcu, Feyza; Çulhaoğlu, SüleymanIn this study, the novel Schiff base monomers were synthesized by condensation reactions. Then, these monomers were converted to poly(azomethine-ether)s by oxidative polycondensation (OP) reactions in an aqueous alkaline medium. The structural characterizations of compounds were carried out by FT-IR, NMR, and size exclusion chromatography (SEC). According to the SEC analysis, the calculated number-average molecular weight (M-n), weight average molecular weight (M-w), and polydispersity index values of P-2 and P-4 were found to be 17,500gmol(-1), 24,400gmol(-1), and 1.39; and 18,700gmol(-1), 25,600gmol(-1), and 1.36, respectively. The HOMO-LUMO energy levels, electrochemical (E-g'), and optical (E-g) band gaps of polymers were calculated from cyclic voltammetry (CV) and UV-vis measurements, respectively. CV was used to determine the electrochemical oxidation-reduction characteristics of polymers. Thermal characterizations of compounds were made by using TG-DTA and DSC techniques. According to TG analysis, polymers with higher initial degradation temperatures (T-on) than those of their monomers indicate that the synthesized polyphenols have higher thermal stabilities than their monomer species.
