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    Öğe
    Dependence of 400 MHz NMR Peak Line Widths of Crude Oil on well Characteristics
    (Springer, 2024) Kal, Duzgun; Sunkur, Murat; Koylu, M. Zafer; Yilmaz, Ali
    Today, magnetic field inhomogeneity in high-field NMR machines is minimized by proper shimming of the machine and extensive dilution of the sample with deuteron solvents. Hence, the line width (LW) measurements of the NMR peaks are reliable for NMR studies. This study is aimed at examining the relationship between the crude oil properties and the LW values of the CH2 and CH3 peaks and the relationship between the LW of water in crude oil and the percentage of water. A set of 22 mixtures was prepared by adding 0.02 mL of each crude oil to each 0.98 mL of CDCl3. A suitable NMR spectrum, including the water peaks of the mixtures, was obtained with a spectrometer operating at 400 MHz. Paraffinic CH2 and CH3 peak LWs vary from well to well. Paraffinic CH3 LW decreases nearly linearly with American Petroleum Institute gravity. In addition, the LW of the water peak at 4.75 ppm is strongly related to the percentage of water in crude oil. The mixtures used in this study provide the appropriate NMR peaks for CH2, CH3, and water in crude oil. NMR peaks of water in crude oil were displayed for the first time in the high field. Some of the previous results obtained in the low-NMR field were found. Therefore, this study suggests an additional approach for high-field NMR studies in petroleum chemistry.
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    Öğe
    Design, preparation and application of a Pirkle-type chiral stationary phase for enantioseparation of some racemic organic acids and molecular dynamics studies
    (Acg Publications, 2017) Cakmak, Resit; Ercan, Selami; Sunkur, Murat; Yilmaz, Hayrullah; Topal, Giray
    This study consists of two parts. In the first part of the study; a Pirkle-type chiral stationary phase was prepared by synthesizing an aromatic amine derivative of (R)-2-amino-1-butanol as a chiral selector and binding to L-tyrosine-modified cyanogen bromide (CNBr)-activated Sepharose 4B and then, packed into the separation column. The chromatographic performance of the separation column was evaluated with racemic mandelic acid and 2-phenylpropionic acid by using phosphate buffers at three different pHs as mobile phase. In the resolution processes, the prepared solutions were loaded onto the separation column at two different concentrations and at three different pHs for each racemic organic acid, separately. Enantiomeric excess (ee%) of the eluates was determined on CHIRALPAK AD-H chiral analytical column by HPLC. The maximum ee% for mandelic acid and 2-phenylpropionic acid was determined to be 60.84 and 27.4, respectively. Separation factors (k(1)', k(2)', alpha, and Rs) were calculated for each acid. The structures of the obtained compounds were characterized using the spectroscopic methods (NMR, and elemental analysis). In the second part of the study; enantioselective interactions between the prepared CSP and the analytes have been widely studied by docking, molecular dynamics simulation and quantum mechanical computation methods. The reason of column eluation of rac-2-phenylpropionic acid with lower enantiomeric yield was explained by these techniques.
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    Öğe
    Imine containing C2-Symmetric chiral half sandwich ?6-p-cymene-Ru(II)- phosphinite complexes: Investigation of their catalytic activity in the asymmetric transfer hydrogenation of ketones
    (Elsevier, 2020) Saleh, Najmuldain Abdullah; Pasa, Salih; Kayan, Cezmi; Meric, Nermin; Sunkur, Murat; Aral, Tarik; Aydemir, Murat
    New chiral C-2-symmetric bis(phosphinite) ligands containing imine group were synthesized from 1-({[(1R,2R)-2-{[(2-hydroxynaphthalen-1-yl)methylidene] amino}cyclohexyl]- imino}methyl)- naphthalen-2-ol and two equivalents of Ph2PCl, (i-Pr)(2)PCl or (Cy)(2)PCl, in high yields. Binuclear C-2-symmetric half sandwich eta(6)-p-cymene-Ru(II) complexes of the chiral phosphinite ligands were synthesized by treating of [Ru(eta(6)-p-cymene)(mu-Cl)Cl](2) with the phosphinites in 1:1 M ratio in CH2Cl2. Their catalytic activities in asymmetric transfer hydrogenation (ATH) were investigated for the reaction of acetophenone derivatives with isopropyl alcohol. The corresponding optically active secondary alcohols were obtained in excellent levels of conversion (96-99%) and moderate enantioselectivity (up to 60% ee). Among three complexes investigated, complex 4 was the most efficient one. (C) 2019 Elsevier B.V. All rights reserved.
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    Novel C2-symmetric macrocycles bearing diamide-diester groups
    (Amer Chemical Soc, 2008) Sunkur, Murat; Baris, Deniz; Hosgoren, Halil; Togrul, Mahmut
    We synthesized a series of novel macrocycles with diamide-diester groups (S,S)-1, (S,S)-2, (S,S)-3, and (R,R)-1, derived from dimethyloxalate and amino alcohols by high dilution technique, and evaluated enantiomeric recognition properties of these macrocycles toward primary alkyl ammonium salts by H-1 NMR titration. Taking into account the host employed, important differences were observed in the K-a values of (R)-Am and (S)-Am for (S,S)-1 and (R,R)-1 hosts, K-S/K-R = 5.55 and K-R/K-S = 3.65, Delta Delta G(o) = 0.43 and -0.32 kJ mol(-1), respectively. There seems a general tendency for the host to include the guests with the same absolute configuration.
  • Küçük Resim
    Öğe
    Structural and electronic characterization of silicon based MIS contact by xanthene dye molecules (Erythrosine B)
    (Elsevier B.V., 2023) Sunkur, Murat; Ava, Canan Aytuğ; Güllü, Ömer
    The effect of erythrosine B (ERY) organic material as an interface layer on the electronic characteristics of the Al/p-Si junction is examined in the present work. AFM, NMR, UV–Vis and FTIR measurements have been conducted on the ERY dye molecule. The ERY film on the surface of the substrate is coated with nanoparticles, according to the surface analysis performed using the AFM technique. The basic diode parameters of Al/p-Si and Al/ERY/p-Si junctions were measured by utilizing current-voltage (I–V) and capacitance-voltage (C-V) techniques. The junctions with and without organic interfacial layers were found to have ideality factors of 1.931 and 1.925, respectively. For MS and MIS contacts, the estimated values of barrier height were 0.592 eV and 0.937 eV, respectively. Additionally, the series resistances for the MS and MIS structures by utilizing Norde function, were determined to be 0.14 kΩ and 322.85 kΩ, respectively. In addition, the reverse bias 1/C2-V characteristics were used to analyze the barrier height values and compare the findings to those from I-V method. The experimental findings demonstrated that the Al/ERY/p-Si MIS diode has a barrier height that is remarkably greater than that of the reference Al/p-Si junction. Placement of the ERY dye interlayer between a metal and a semiconductor could enhance and regulate the performance and characteristic of these types of junctions.
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    Öğe
    Synthesis, structural characterization of new macrocyclic Schiff base derived from 1,6-bis(2-formylphenyl)hexane and 2,6-diaminopyridine and its metal complexes
    (Natl Inst Science Communication-Niscair, 2008) Ilhan, Salih; Ternel, Hamdi; Sunkur, Murat; Tegin, Ibrahim
    A macrocyclic ligand has been synthesized by reaction of 2,6-diaminopyridine and 1,6-bis(2-formylphenyl).hexane. Its complexes with Cu(II), Ni(II), Pb(II), Zn(II), Cd(II) and La(III) have been synthesized by the reaction of ligand and Cu(ClO4)(2)center dot 6H(2)O, Ni(ClO4)(2)center dot 6H(2)O, Pb(ClO4)(2)center dot 6H(2)O, Zn(ClO4)(2)center dot 6H(2)O, Cd(ClO4)(2)center dot 6H(2)O and La(ClO4)(3)center dot 6H(2)O, respectively. The ligand and its metal complexes have been characterized. All complexes are diamagnetic while the Cu(II) complex is binuclear.