Yazar "Culhaoglu, Suleyman" seçeneğine göre listele

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    Comparative Study of Bis-Schiff Case Containing Conjugated Oligomers Based on Phosphate and Silane Moieties: Investigation of Photophysical and Thermal Properties
    (Amer Chemical Soc, 2024) Kolcu, Feyza; Culhaoglu, Suleyman; Kaya, İsmet
    Oligo(azomethine)s bearing phosphate and silane moieties were the subject of an investigation within this study. The initial stage involved the synthesis of two Schiff base monomers, denoted as SCH-1 and SCH-2 (SCHs), each possessing a pair of hydroxyl functional groups. This was achieved through a loss of water between the aldehyde and diamine precursors. Subsequently, the Schiff base entities were subjected to oligomerization through HCl-mediated elimination due to the interaction between the hydroxyl groups of the Schiff bases and the chlorine moieties of dichlorodiethylsilane (Si) or phenyl dichlorophosphate (P). This procedure yielded distinct P-oligo(azomethine) (P1-P, P2-P) and Si-oligo(azomethine) (P1-Si and P2-Si) structures corresponding to each precursor. The molecular structures of the synthesized Schiff base monomers and oligo(azomethine)s were elucidated employing Fourier transform infrared, H-1 NMR, and C-13 NMR techniques. Thermal properties of the resulting products were assessed by utilizing thermogravimetric analysis (TG-DTG/DTA and DSC) techniques. Scanning electron microscopy (SEM) was employed to acquire high-resolution images and detailed surface information on the samples. Additionally, X-ray diffraction was employed to analyze the phase properties of the solid samples. Furthermore, the optical band gap (E-g) values of the resulting P-oligo(azomethine)s and Si-oligo(azomethine)s were determined utilizing UV-vis spectrophotometer. The relatively low band gap values exhibited by the synthesized oligo(azomethine)s were indicative of their potential suitability as semiconductive materials in the realm of electronic and optoelectronic device fabrication. Photoluminescence (PL) measurements disclosed a green emission profile upon excitation by blue light. The oligo(azomethine)s incorporating methoxy groups demonstrated a red shift in comparison to their counterparts with methyl groups. Remarkably, no discernible fluctuations in fluorescence were observed over a 3600 s interval under consistent conditions. This observation underscored the inherent stability of the PL emission across the spectral range of exciting light. Thermal analyses unveiled high thermal stability of the synthesized oligo(azomethine)s, sustaining their structural integrity up to 220 degrees C. The char % of P-oligo(azomethine)s and Si-oligo(azomethine)s were observed to fall within the range of 29.45-55.47% at 1000 degrees C. SEM images revealed the absence of pores on the surface of P2-Si, which exhibited the highest limiting oxygen index and thermal heat release index (T-HRI) values.
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    Syntheses and characterizations of oligo(azomethine ether)s derived from 2,2?-[1,4-enylenebis (methyleneoxy)]dibenzaldehyde and 2,2?-[1,2-phenylenebis (methyleneoxy)]dibenzaldehyde
    (Springer, 2012) Kaya, İsmet; Culhaoglu, Suleyman
    The oligo(azomethine ether)s were synthesized via polycondensation of alkyl diamines with aromatic dialdehydes. Two series of dialdehydes, namely 2,2'-[1,2-phenylenebis(methyleneoxy)]dibenzaldehyde [2,2'-1,2-(PBMODB)] and 2,2'-[1,4-phenylenebis(methyleneoxy)]dibenzaldehyde [2,2'-1,4-(PBMODB)] were prepared from the condensation reactions of salicylaldehyde with o-xylenedibromide and p-xylenedibromide, respectively. The structures of dialdehydes and oligomers were determined by FT-IR, H-1-NMR and C-13-NMR. The thermal analyses of oligomers were conducted by DSC and TG/DTA techniques, respectively. Size exclusion chromatography (SEC) technique was also used to determine molecular weights and molecular weight distributions of oligomers. Electrochemical properties of the synthesized products were investigated.
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    Syntheses, structures and properties of novel oligo(azomethine ether)s containing or not chlorine atoms in the main chain
    (Industrial Chemistry Research Inst, 2009) Kaya, İsmet; Culhaoglu, Suleyman
    New oligoazomethines were synthesized via polycondensation of aromatic diamines with one of two dialdehydes. Both dialdehydes, namely 4-({2-[(4-formylphenoxy)methyl]benzyl}oxy)benzaldehyde (2-FPMBB), and 4-({4-[(4-formylphenoxy)methyl]benzyl}oxy)benzaldehyde (4-FPMBB) were prepared from p-hydroxybenzaldehyde with o-xylenedibromide or p-xylenedibromide, respectively. Dialdehydes and oligomers were characterized by FT-IR, H-1 NMR and C-13 NMR methods. Size exclusion chromatography (SEC) technique was used to determine molecular weights and molecular weight distributions of synthesized oligomers. The thermal stability of oligomers was conducted by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The weight losses of oligoazomethines (O1, O2, O3 and O4) at 1000 degrees C were found to be 54.74, 46.27, 54.85 and 53.10% respectively. In all cases, the imine (-HC=N-) linkage is the first breaking group due to the high temperature. It can be seen from TGA that oligo(azomethine ether)s containing chlorine atoms have higher thermal stability at 1000 degrees C than O1 and O3 oligomers.
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    Synthesis, Characterization and Conductivity Properties of Novel Oligomer Schiff Bases Derived from 4-Amino-3-hydrazino-5-mercapto-1, 2, 4-triazole and Their Reactions with VO(IV), Cu(II) Ions
    (Springer, 2014) Kaya, İsmet; Ercag, Ayse; Avci, Ali; Culhaoglu, Suleyman
    A new Schiff base, 4-(4-hydroxysalicylidenamino)-3-hydrazino-5-mercapto-1,2,4-triazole (4HSAHMT), and novel Schiff base oligomers of 4-salicylidenamino-3-hydrazino-5-mercapto-1,2,4-triazole (SAHMT), 4-(2-hydroxynaphthylidenamino)-3-hydrazino-5-mercapto-1,2,4-triazole (2HNAHMT), 4-(4-hydroxysalicylidenamino)-3-hydrazino-5-mercapto-1,2,4-triazole (4HSAHMT) and 4-(5-bromosalicylidenamino)-3-hydrazino-5-mercapto-1,2,4-triazole (BrSAHMT) were synthesized via oxidative polymerization using NaOCl as the oxidant. The structures of the oligomers were supported by FT-IR, UV-Vis, H-1-NMR, and C-13-NMR techniques. The compounds were further characterized by solubility tests, TG-DTA, and elemental analysis. The molecular weight distribution parameters of the compounds were determined by the size exclusion chromatography (SEC). According to SEC, the number average molecular weight (M (n) ) values of O-SAHMT, O-BrSAHMT, O-4HSAHMT and O-2HNAHMT were 2,700, 2,100, 2,700 and 1,000 g mol(-1), respectively. The weight losses of O-SAHMT, O-BrSAHMT, O-4HSAHMT and O-2HNAHMT were 73, 76, 80 and 54 %, respectively, at 1,000 A degrees C. TG analyses showed that the synthesized oligomers were stable toward thermal decomposition. The synthesized oligomers were converted to metal complexes with salts of VO(IV) and Cu(II). The doped and undoped electrical properties of oligomers and oligomer-metal complexes were determined by the four-point probe technique at room temperature and atmospheric pressure.
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    Synthesis, characterization, optical, and electrochemical properties of thermal stable novel poly(azomethine-ether)s
    (Taylor & Francis Ltd, 2014) Kaya, İsmet; Avci, Ali; Kolcu, Feyza; Culhaoglu, Suleyman
    In 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.
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    Synthesis, characterization, thermal and band gap values of poly(azomethine-ether)s containing aromatic and aliphatic group
    (Taylor & Francis Inc, 2020) Culhaoglu, Suleyman; Kaya, İsmet
    In this study, we proposed to synthesize soluble poly(azomethine-ether)s derivatives containing aromatic rings and long alkyl groups. For this reason, long alkyl groups containing double bromide or chloride atoms were chosen to synthesize diamines monomers (DIAMs). Seven different poly(azomethine-ether)s were synthesized from the condensation reaction of DIAMs with 4,4 '-[1,4-phenylenebis(methyleneoxy)]dibenzaldehyde (PBMODB). The structures of compounds were confirmed by FT-IR, UV-Vis,H-1-NMR and(13)C-NMR techniques. The molecular weight distributions of synthesized poly(azomethine-ether)s were determined by size exclusion chromatography (SEC). The synthesized compounds were characterized by solubility tests, TG-DTA and DSC. Optical band gaps of poly(azomethine-ether)s (E-g) were also calculated by UV-Vis spectrophotometer. Electrical conductivities of synthesized poly(azomethine-ether)s were measured by four-point probe technique using a Keithley 2400 electrometer. It was stressed that synthesized poly(azomethine-ether)s were found to be insulators which have a potential for electronic and optoelectronic applications, with fairly high band gaps. Thermal stability properties of synthesized poly(azomethine-ether)s were found to be stable up to 300 degrees C. The chars of them were observed between 33 and 45% at 1000 degrees C. Poly(azomethine-ether)s containing flexible ether groups and long alkyl chains showed good solubility in aprotic organic solvents.
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    Synthesis, Characterization, Thermal Stability and Conductivity of New Schiff Base Polymer Containing Sulfur and Oxygen Bridges
    (Polymer Soc Korea, 2015) Culhaoglu, Suleyman; Kaya, İsmet
    In this study, we proposed to synthesize thermally stable, soluble and conjugated Schiff base polymer (SbP). For this reason, a specific molecule namely 4,4'-thiodiphenol which has sulfur and oxygen bridge in its structure was used to synthesize bi-functional monomers. Bi-functional amino and carbonyl monomers namely 4,4'-[thio-bis(4,1-phenyleneoxy)]dianiline (DIA) and 4,4'-[thiobis(4,1-phenyleneoxy)]dibenzaldehyde (DIB) were prepared from the elimination reaction of 4,4'-thiodiphenol with 4-iodonitrobenzene and 4-iodobenzaldehyde, respectively. The structures of products were confirmed by elemental analysis, FTIR, H-1 NMR and C-13 NMR techniques. The molecular weight distribution parameters of SbP were determined by size exclusion chromatography (SEC). The synthesized SbP was characterized by solubility tests, TG-DTA and DSC. Also, conductivity values of SbP and SbP-iodine complex were determined from their solid conductivity measurements. The conductivity measurements of doped and undoped SbP were carried out by Keithley 2400 electrometer at room temperature and atmospheric pressure, which were calculated via four-point probe technique. When iodine was used as a doping agent, the conductivity of SbP was observed to be increased. Optical band gap (E-g) of SbP was also calculated by using UV-Vis spectroscopy. It should be stressed that SbP was a semiconductor which had a potential in electronic and optoelectronic applications, with fairly low band gap. SbP was found to be thermally stable up to 300 degrees C. The char of SbP was observed 29.86% at 1000 degrees C.
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    Synthesis, optical and electrochemical abilities of highly soluble poly(epoxy-ether)s bearing perylene bisimide units and their enhanced thermal properties by curing process
    (Elsevier Science Sa, 2019) Kolcu, Feyza; Culhaoglu, Suleyman; Kaya, İsmet
    Three highly fluorescent poly(epoxy-ether) containing three different units at two imide functionalities of perylene bisimide unit (PER-EP1, PER-EP2 and PER-EP3) could be efficiently synthesized in high yields, and were characterized by FT-IR, H-1 NMR and (CNMR)-C-13-N- spectroscopic techniques. Their optical properties were measured using UV-vis and emission spectroscopic methods, as well as cyclic voltammetry (CV) to analyze their electrochemical abilities. They all showed emission in the visible region. Additionally, one reversible one-electron oxidation and two reversible one-electron reductions in acetonitrile took place for the synthesized poly(epoxy-ether)s. Dihydroxy compounds containing perylene units exhibited three absorption maxima (lambda(max)) values of 458, 489 and 524 nm in DMF owing to presence of perylene units and highly conjugated framework of bonds. For poly(epoxy-ether)s, the functional groups influenced the conjugated systems, giving rise to the absorption peaks to shift to longer wavelengths. Fluorescence spectra of the synthesized poly(epoxy-ether)s in DMF showed emission peaks in the wavelength range of green light, and the highest value of fluorescence quantum yield was 8.2% for PER-EP1 in comparison to standard fluorescein solution. Furthermore, morphological analysis demonstrated that the synthesized poly(epoxyether)s possessed well-organized microstructure particles despite the linkage of the perylene bisimide core. The prepared epoxy resins were cured with p-phenylenediamine as aromatic hardener. The resulting cured epoxy resins were analyzed for their thermal properties such as thermal stability, char yield, glass transition temperature (T-g) and flame retardancy. The morphology behaviour was performed by SEM analysis on poly(epoxy-ether)s.