• Journal of the Korean Chemical Society
• /
• v.24 no.1
• /
• pp.44-52
• /
• 1980

Ionic dissociation rates of $\alpha$-chlorobenzyl ethyl ether in each solvent of toluene-$d_8$ and carbon tetrachloride were measured by the method of dynamic NMR spectroscopy. The spin system of these 1H NMR spectra was $AB_3$. The theoretical spectrum was calculated by computer simulation of dynamic NMR spectra, which agreed very well with observed spectra. From this computer simulation, the ionic dissociation rate constant k was obtained, and by Eyring plot with it, slope and intercept length was gained, from which kinetic parameters were calculated.The easiness of ionic dissociation depended upon solvent polarity. Activation enthalpy was 4.7 kcal/mole in toluene-$d_8$, 10.7 kcal/mole in carbon tetrachloride, and activation entropy was -35. 8 e.u. in toluene-$d_8$, -14.4 e.u. in carbon tetrachloride. It was understood that though the ${\Delta}H^{neq}$ value was small, this ionic dissociation had an easier procession in nonpolar solvents with increasing temperatures. Considering that the ionic dissociation could be thought as the first step of $S_N1$ mechanism, attention might be paid to the results that the value of ${\Delta}S^{neq}$ had a large negative value in comparison with a small ${\Delta}H^{neq}$.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.10
• /
• pp.1682-1687
• /
• 2007

The differences in the nonvolatile metabolites of pine-mushrooms (Tricholoma matsutake Sing.) according to different parts and heating times were analyzed by applying principal component analysis (PCA) to $^1H$ nuclear magnetic resonance (NMR) spectroscopy data. The $^1H$ NMR spectra and PCA enabled the differences of nonvolatile metabolites among mushroom samples to be clearly observed. The two parts of mushrooms could be easily discriminated based on PC 1, and could be separated according to different heattreated times based on PC 3. The major peaks in the $^1H$ NMR spectra that contributed to differences among mushroom samples were assigned to trehalose, succinic acid, choline, leucine/isoleucine, and alanine. The content of trehalose was higher in the pileus than in the stipe of all mushroom samples, whereas succinic acid, choline, and leucine/isoleucine were the main components in the stipe. Heating resulted in significant losses of alanine and leucine/isoleucine, whereas succinic acid, choline, and trehalose were the most abundant components in mushrooms heat-treated for 3 min and 5 min, respectively.

• Bulletin of the Korean Chemical Society
• /
• v.8 no.5
• /
• pp.372-376
• /
• 1987

Acetone solution of quinoline-8-carbaldehyde reacts with $[Rh(cod)(PPh_3)_2] PF_6$and $[Ir(cod)(PPh_3)_2] PF_6$ to yield $[Rh(NC_9H_6CO)(H)(PPh_3)_2(CH_3COCH_3)] PF_6$ (1) and $[Ir(NC_9H_6CO)(H)(PPh_3)_2(CH_3COCH_3)] PF_6$ (2), respectively. The compound $[Ir(cod)(PPh_3)_2] PF_6$ also reacts with $Ph_2PC_6H_4-o-CHO$ in the acetone / $H_2O$ mixture to give $[Ir(Ph_2PC_6H_4-o-CO)(H)(PPh_3)_2(CH_3COCH_3)] PF_6$ (3). Compounds 1, 2, and 3 were characterized by infrared, $^1H$ NMR, $^{31}P$ NMR spectra and conductivity measurement. The $^1H$ NMR spectra of 1, 2, and 3 support the presence of a terminal hydride that is cis to the phosphine. The IR band of 3 at 2185 $cm^{-1}$, which is assigned to $\nu$(Ir-H), and the hydride cleavage reaction of 3 with $CCl_4$, provide evidence for the Ir-H bond.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.45 no.4
• /
• pp.367-371
• /
• 2012

To investigate the relationship between metabolic changes in $^1H$-nuclear magnetic resonance (NMR) spectra and fish vaccination, serum was collected from olive flounders treated with a formalin-killed Edwardsiella tarda vaccine and used for $^1H$-NMR metabolite profiling. Principal component analysis and partial least squares were applied to the $^1H$-NMR profile to reduce its complexity and establish class-related clusters. Relative lipid regions were distinguished in vaccinated and non-vaccinated serum. Then, the lipids were extracted from the serum and analyzed. Triolein was identified.

• Analytical Science and Technology
• /
• v.7 no.4
• /
• pp.505-515
• /
• 1994

$^1H$ NMR spectra for monocyanide ligated ferriprotoporphyrin(hemin) complex and dicyanide coordinated hemin complex in dimethylsulfoxide(DMSO-$d_6$) solution have been recorded and analyzed. NMR spectra of hemin-cyanide complexation in DMSO-$d_6$ exhibit that the cyanide ligation to hemin is temperature-dependent. Thermodynamic parameters for the monocyanide ligated hemin to dicyanide ligated hemin are consistent with endothermic process with ${\Delta}H^{\circ}=736.6cal/mol$ and ${\Delta}S^{\circ}=16.4eu$. Detailed analysis of the anomalous deviation from Curie behavior for CN/DMSO coordinated hemin complex demonstrates the presence of a high spin character, and this weaker axial field relative to the purely low-spin dicyanide hemin complex is supposed to attribute to instantaneously ruptured iron-DMSO bond. This complex may serve as a useful model to characterize electronic/molecular structure of hemoproteins, which one of axial ligands is weak.

• Bulletin of the Korean Chemical Society
• /
• v.20 no.10
• /
• pp.1149-1152
• /
• 1999

1H NMR spectrum of a DMF-d7 solution containing 4-aminopyrimidine and [SiW11CoIIO39]6- (SiW11Co) shows separate peaks from two linkage isomers, a and b, in which N(1) and N(3) of the pyrimidine ring are coordinated to SiW11Co, respectively. The signal from the amine group in the isomer a exhibits temperature dependence that is characteristic of a two-site exchange problem. Rates of internal rotation of the amine group were determined by simulating the NMR spectra at 5-35℃. The amine group of free 4-aminopyrimidine also shows temperature-dependent spectra at lower temperatures; rates of internal rotation at (-25)-25℃ were determined. The internal rotation of the amine group in the complex is much slower than that for free 4-aminopyrimidine, indicating that π-character of the C-N bond increases on coordination to SiW11Co. The amine group in the isomer b does not show such behavior. It is probable that hydrogen bonding between N-H and a bridging oxygen atom of SiW11Co prevents it from rotating at low temperatures.

• Bulletin of the Korean Chemical Society
• /
• v.9 no.3
• /
• pp.176-179
• /
• 1988

3-Methoxy-4-cyano-2,9-dioxabicyclo[4.3.0]non-3-e ne (1) was prepared by (4 + 2) cycloaddition reaction of methyl ${\alpha}$-cyanoacrylate with 2,3-dihydrofuran. Compound 1 was ring-open polymerized by cationic catalyst such as boron trifluoride etherate to obtain alternating head-to-head (H-H) copolymer (2) of methyl $\alpha$ -cyanoacrylate and 2,3-dihydrofuran. For comparison, head-to-tail (H-T) copolymer (3) was also prepared by free radical copolymerization of the corresponding monomers. The H-H copolymer exhibited minor differences in its $^1H$-NMR and IR spectra, but in the $^{13}C$-NMR spectra significant differences were observed between the H-H and H-T copolymers. All of the H-H and H-T copolymers were soluble in common solvents and the inherent viscosities were in the range 0.2-0.3 dl/g.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.2
• /
• pp.687-692
• /
• 2011

$^1H$ and $^{13}C$ NMR spectra of series of (E)-1-aryl-(2- and 3-thienyl)-2-propenones, that are aldol condensation products between 2- and 3-thiophenecarbaldehydes and m- and p-substituted acetophenones, were examined to make complete assignments of the chemical shifts. Long range couplings, $^4J$ and $^5J$, are observed in the $^1H-^1H$ COSY of both 2- and 3-thienyl compounds, which makes the elucidation of the conformation in solution possible. In contrast, the 2-furyl analogue shows the long range coupling phenomena, but the 3-furyl and phenyl analogues do not show similar phenomena.

• Archives of Pharmacal Research
• /
• v.13 no.3
• /
• pp.246-251
• /
• 1990

Intermolecular interaction between barbiturates and membrane components such as phospholipid and cholesterol were investigated on $^1$H-NMR spectra and infrared spectra. According to previous reports, barbiturates interacted with phospholipid through intermolecular hydrogen bonds. We also investigated thi observation using dipalmitoyl-phosphatidylcholine (DPPC) as phospholipid in deuterochloroform, and characterized quantitatively. Also, the observed drug could interact with cholesterol which is one of the major components of biomembranes through hydrogen bonds. It was the carbonyl groups of barbiturate and the hydroxyl group of cholesterol that formed hydrogen bond complex. In addition to spectroscopic studies, we investigated the direct effect of phenobarbital on lipid multibilayer vesicles, whose compositions were varied, by calorimetric method. Phenobarbital caused a reduction in the temperature of phase transition of vesicles. These studies may provided a basis for interpreting the mode of action of barbiturates.

• Journal of the Korean Chemical Society
• /
• v.51 no.4
• /
• pp.339-345
• /
• 2007

Urea reacts with PtCl2, H2[PtCl6]·6H2O, H2[IrCl6] and Ni(CH3CO2)2 in aqueous solution at high temperature (60-80 °C) yielding [PtCl2(Urea)]·2H2O (1), (NH4)2[PtCl6] (2), (NH4)2[IrCl6]·H2O (3) and [Ni2(OH)2(NCO)2(H2O)2] (4) complexes, respectively. In complex 1, urea coordinates to Pt(II) as a neutral bidentate ligand via amido nitrogen atoms. In complexes 2, 3 and 4 it seems that the coordinated urea molecules decompose during the reaction at high temperature and a variety of reaction products are obtained. All complexes were isolated in moderate yields as dark green (1), yellow (2), pale brown (3) and faint green (4) precipitates, respectively. The reaction products were characterized by their microanalysis, IR, 1H and 13C NMR spectra as well as thermal analysis. General mechanisms describing the formation of these complexes were suggested.