Yazar "Yildirim, Mehmet" seçeneğine göre listele

Listeleniyor 1 - 7 / 7
  • [ X ]
    Öğe
    Molecular weight dependent antistaphylococcal activities of oligomers/polymers synthesized from 3-aminopyridine
    (Serbian Chemical Soc, 2010) Akgul, Cahit; Yildirim, Mehmet
    The main aim of this study was to investigate the relationship between molecular weight and the antistaphylococcal activity of oligomers/polymers synthesized from 3-aminopyridine. Different oligomers/polymers were synthesized from 3-aminopyridine by changing the oxidative polycondensation reaction conditions. They were characterized by size exclusion chromatography and their antibacterial activities were compared by employing standardized susceptibility assays. The obtained experimental results demonstrated that 3-aminopyridine had no antistaphylococcal activity. However, as a result of polymerization, strong antistaphylococcal activity was obtained. Oligomers/polymers synthesized from 3-aminopyridine had varying degrees of antistaphylococcal activity and the maximum activity was obtained from relatively very short oligomers. It was therefore concluded that polymerization of 3-aminopyridine is required for antistaphylococcal activity and strength of this activity depends on the molecular weights of the synthesized molecules.
  • [ X ]
    Öğe
    Novel hexapodal triazole linked to a cyclophosphazene core rhodamine-based chemosensor for selective determination of Hg2+ ions
    (Springer/Plenum Publishers, 2014) Ozay, Hava; Kagit, Reyhan; Yildirim, Mehmet; Yesilot, Serkan; Özay, Özgür
    The hexapodal Rhodamine B derivative compound 3 containing a cyclotriphosphazene core was synthesized and characterized by spectroscopic techniques such as FT-IR, H-1, C-13 and P-31 NMR, HR-MS, MALDI MS and microanalysis. Compound 3 is a naked eye selective sensor with colorimetric and fluorescent properties for Hg2+ ions in the presence of other metal ions such as Na+, K+, Ca2+, Ba2+, Mg2+, Ag+, Mn2+, Cu2+, Ni2+, Co2+, Pb2+, Cd2+, Zn2+, Fe2+, Fe3+, and Cr3+. The optical sensor properties of compound 3 were investigated using UV-vis and fluorescence spectroscopy. The lowest detection limit of compound 3 was determined as 3.76 x 10(-9) M (0.75 ppb) for Hg2+ ions. The stoichiometry of compound 3-Hg2+ complex was found to be 1:3 (ligand/metal ion). The reusable test strip was improved by the immobilization of compound 3 into a hydrogel network. The reusability of the sensor and test strip was tested with S2- ion solutions.
  • [ X ]
    Öğe
    Phosphazene Based Multicentered Naked-Eye Fluorescent Sensor with High Selectivity for Fe3+ Ions
    (Amer Chemical Soc, 2014) Kagit, Reyhan; Yildirim, Mehmet; Özay, Özgür; Yesilot, Serkan; Ozay, Hava
    A novel on/off fluorescent rhodamine-based hexapodal Fe3+ probe (L) containing a cyclotriphosphazene core was synthesized by an azide-alkyne click-reaction. The synthesized compounds (1-5 and L) were characterized by FT-IR; H-1, C-13, and P-31 NMR; and MALDI MS spectrometry. The optical sensor features for the Fe3+ complex of L were investigated by UV-vis and fluorescence spectroscopy. The stoichiometry of L-Fe3+ complex was found to be 1:3 (ligand/metal ion), and the detection limit of L was determined as 4.8 mu M (0.27 mg L-1) for Fe3+ ions. The reusability of the sensor was tested by the addition of ethylenediamine to L-Fe3+ complex solutions followed by the addition of Fe3+ solution.
  • [ X ]
    Öğe
    Synthesis and characterization of novel urea and thiourea substitute cyclotriphosphazene compounds as naked-eye sensors for F- and CN- anions
    (Tubitak Scientific & Technological Research Council Turkey, 2015) Ozay, Hava; Yildirim, Mehmet; Özay, Özgür
    Novel hexakisurea and thiourea cyclotriphosphazene compounds (3-7) were synthesized. The structure of all compounds was identified using FT-IR H-1, C-13, and P-31 NMR spectroscopy; MALDI-TOF MS; and elemental analysis. The optical sensor properties for anions of 3-7 were investigated using UV-Vis spectroscopy. It was determined that compounds 6 and 7 are spectrophotometric and naked eye sensors for F- and CN- anions, respectively. Sensor properties of these compounds for anions were investigated using UV-Vis spectroscopy. The stoichiometry of host guest complexes was found to be 1:6.
  • [ X ]
    Öğe
    SYNTHESIS, CHARACTERIZATION, AND NAKED-EYE SENSOR APPLICATION OF FULLY SUBSTITUTED UREA-BASED CYCLOTRIPHOSPHAZENE COMPOUND
    (Taylor & Francis Ltd, 2015) Ozay, Hava; Yildirim, Mehmet; Özay, Özgür
    A novel sensor with a hexacenter containing nitrophenylurea groups on a cyclotriphosphazene core was synthesized by click reaction of N-propargyl-substituted urea with a hexaazide-substituted cyclotriphosphazene compound. It was characterized by spectroscopic techniques such as Fourier transform infrared spectroscopy, nuclear magnetic resonance, and mass spectroscopy. This compound was used for naked-eye and spectrophotometric detection of F- anions. The optical sensor properties of compound were investigated using ultraviolet-visible spectroscopy.
  • [ X ]
    Öğe
    Synthesis, structural characterization, and anion interactions of new triazole-linked urea derivative fully substituted cyclotriphosphazene compounds
    (Taylor & Francis Ltd, 2017) Özay, Özgür; Yildirim, Mehmet; Ozay, Hava
    Three novel fully substituted urea derivative cyclotriphosphazene compounds 5-7 were synthesized by alkyne-azide 1,3-dipolar cycloaddition reaction of propargyl substituted ureas 2-4 with hexaazide substituted cyclotriphosphazene 1 in the presence of Cu(I) catalyst. All compounds were characterized with spectroscopic techniques such as FT-IR, H-1, C-13, and P-31 nuclear magnetic resonance and mass spectroscopy. Also, the usefulness of compounds 5-7 as anion carriers was investigated by H-1 NMR spectroscopy. For this purpose, H-1 NMR spectra of compounds 5-7 were recorded in the presence of tetrabutylammonium fluoride in DMSO-d(6). It was determined, that the urea protons in the compounds interact with fluoride.
  • [ X ]
    Öğe
    Waterlogging Response of Lentil Cultivars Grown in Greenhouse Throughout The Early Vegetative and Recovery Period
    (Centenary University, 2023) Eliş, Seval; Biçer, Behiye Tuba; Yildirim, Mehmet
    Under conditions of global climate change, the frequency of climate anomalies is predicted to increase. One of these issues is the problem of waterlogging in agricultural areas as a direct result of the unexpected and severe rainfall that has occurred over the last decades. In this study, the morphological responses to waterlogging stress and the recovery capacity of the lentil cultivars were investigated. A waterlogging stress study was conducted in small water pools with four different lentil varieties (Çağıl, Fırat 87, Kafkas and Kayı). Lentil cultivars were exposed to waterlogging stress for 7 and 14 days in the same greenhouse conditions. Measurements were taken at the end of 7 and 14 days of waterlogging (W-7 and W-14) and during the recovery period after flowering (R-7 and R-14). Lentil cultivars and plant traits were negatively affected by waterlogging stress applications (W-7 and W-14). According to the study, 14-day waterlogging had a greater impact on lentil cultivars than 7-day waterlogging. Total biomass measured after flowering at R-7 and R-14 waterlogging decreased by about 31.5% and 49.3%, respectively. Çağıl cultivar had a tolerance to waterlogging stress, but Kafkas cultivar was sensitive to waterlogging stress. © 2023, Centenary University. All rights reserved.