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Öğe 1H NMR study of chiral monoaza-15-crown-5 ether derivative by relaxation time T1(Asian Journal Of Chemistry, 2008) Askin, Muzaffer; Koylu, M. Zafer; Tutsi, MizginMeasurement of spin-lattice relaxation time T has been performed for the chiral monoaza-15-crown-5 ether derivative as a function of temperature. Activation energies E. and correlation times (tau(c)) were obtained. The data suggest that the underlying mechanism of relaxation is due to magnetic dipole-dipole interaction.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, AliToday, 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.Öğe Enantioselective complexation of chiral lariat crown ethers and chiral primary alkylammonium perchlorates(Tubitak Scientific & Technological Research Council Turkey, 2011) Koylu, M. Zafer; Aral, Tarik; Karakaplan, Mehmet; Kocakaya, Safak Ozhan; Hosgoren, HalilIn order to investigate the enantiomeric recognition abilities toward 2 chiral alkylammonium perchlorates (AmI, AmII) by H-1-NMR titration method in CDCl3, 4 chiral lariat ethers 8-11 with a (p-methoxyphenoxy) methyl flexible side arm were used. The most effective enantiomeric recognition was obtained by LCEs 9 and 11 toward AmII, by K-R/K-S 6.58 and K-S/K-R 6.63, respectively. The effect of macroring size, subunit of macroring, and side arm appeared to have strong influence on the binding ability of these alkylammonium ions.Öğe Estimation of ? value in proton NMR relaxation times of dibenzo diaza 18-crown-6 ether derivative in solution(Elsevier Science Bv, 2006) Yilmaz, Ali; Koylu, M. Zafer; Budak, HaticeSpin-lattice (T-1) and spin-spin (T-2) relaxation times of seven peaks in dibenzo diaza 18-crown-6 ether derivative were measured at 300K with a Bruker 400 MHz NMR spectrometer. An equation was derived for correlation time tau from the ratio of the (1/T-1)/2(1/ T-2) using relaxation formulas pertaining to dipolar interactions. The correlation time was calculated from the equation for each peak using experimental data for (1/T-1)/2(1/T-2) ratio. The estimated tau values ranged from 0.7 ns to 2 ns. The similarity of T values of the peaks belonging to the different parts of the molecule suggested that overall molecular tumbling may be responsible for relaxation mechanism of all the groups. (c) 2006 Elsevier B.V. All rights reserved.Öğe The Examination of a Variety of Different Ions Added to the Crown Ether Derivatives with High Field NMR Spectrometer(Maik Nauka/Interperiodica/Springer, 2017) Askin, Muzaffer; Zengin, Bilgin; Korunur, Sibel; Kor, Harun; Koylu, M. ZaferThe current study involves the measurements of T-1 relaxation time of complexes three different crown ethers (4-aminobenzo-15-Crown-5, 1-Aza-18-Crown-6, 1-Aza-15-Crown-5) and two different ions sodium perchlorate (NaClO4), lithium perchlorate (LiClO4) by a 400 MHz NMR spectrometer. The association constants (K-a) of the complexes were determined on the basis of the evaluation of these measurements using the Benesi-Hildebrand method that we have modified. These association constants were consistent with those obtained from H-1 NMR titration technique. As a result, it can be speculated that binding constants could be measured using T-1 relaxation time when chemical shifts are very small or cannot be observed.Öğe Temperature dependence of NMR T1 relaxation of dibenzo diaza 18-crown-6 ether derivative in solution(Asian Journal Of Chemistry, 2007) Koylu, M. Zafer; Budak, HaticeSpin-lattice relaxation times in one of dibenzo diaza 18-crown-6 ether derivative were measured vs. increasing temperature. The relaxation times (In T-1) were fitted vs. I/T over a temperature range of 313-277 K. A linear relationship with a negative slope was found for each peak. The present data suggest that In T, is nearly linearly proportional to I/T. The data also suggest that dipole-dipole interaction, modulated by whole molecular tumbling, is the source of relaxation.Öğe Temperature Dependence Study of Chiral Ether Derivative by 1H NMR Relaxation Time(Asian Journal Of Chemistry, 2014) Ekinci, Arzu; Koylu, M. Zafer; Askin, MuzafferMeasurement of spin-lattice relaxation time T-1 has been studied for the N-benzil-2-isobutyl aza-15-crown-5 ether derivative as a function of temperature. The data suggest that the underlying mechanism of relaxation rates is due to magnetic dipole-dipole interaction which is the dominant mechanism for the increase in temperature due to increase in the dipolar relaxation mechanism and, modulated by whole molecular tumbling. From In T-1 versus 1/T graph, activation energies (E-a) and correlation times (tau(c)) were obtained.
