• Reproductive and Developmental Biology
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• v.30 no.1
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• pp.13-19
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• 2006

To search of new porcine pheromonal odorants for biostimulation control system technologies to improve reproductive efficiency in livestock species, the comparative molecular field analysis (CoMFA) for binding affinity constant $(p(Od)_{50})$ between porcine odorant binding protein (pOBP) and ligands of odorant 2-(cyclohexyloxy) tetrahydrofurane derivatives as substrate molecule was conducted and discussed. In the optimized CoMFA model AIV with chirality $(C_1'(R),\;C_2(S))$ in substrate molecule and atom based fit alignment (A) of odorants, the statistical results showed the best predictability of the binding affinities $(p(Od)_{50})$ based on the LOO cross-validated value $r^2_{cv}.\;(q^2=0.886)$ and non-cross-validated conventional coefficient $(r^2_{ncv}.=0.984)$. the binding affinity constants exhibited a good correlation with steric (40.8%), electrostatic (14.6%) and hydrophobic (44.6%) factors of the substrate molecules. from the analytical results of the contour maps, which may give us some valuable informations to the modification of odorants for effective binding affinity.

• Reproductive and Developmental Biology
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• v.30 no.3
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• pp.169-174
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• 2006

To search of a new porcine pheromonal odorants, the comparative molecular similarity indices analysis(CoMSIA) between porcine odorant binding protein(pOBP) as receptor and ligands of green odorants 2-(Cyclohexyloxy)tetrahydrofurane derivatives as substrate molecule were conducted and disscused quantitatively. In the optimized CoMSIA model(I-AI) with chirality($I:\;C_{1'}(R),\;C_2(S)$) in substrate molecules and atom based fit alignment(AE) of the odorants the statistical PLS results showed the best predictability of the binding affinities based on the LOO cross-validated value ${r^2}_{cv.}\;(q^2=0.856)$ and non cross-validated conventional coefficient(${r^2}_{ncv.}=0.964)$). The structural distinctions of the highest active molecules were able to understand from the interaction between pOBP and green odorants in the contour maps with CoMSIA model.

• Macromolecular Research
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• v.15 no.6
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• pp.541-546
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• 2007

The combination of atom transfer radical polymerization (ATRP) and click chemistry was employed for the efficient preparation of well-defined block copolymers. Bromo terminated poly(methyl acrylate) (pMA-Br) was prepared by an ATRP initiator, ethyl-2-bromoisobutyrate (EBiB). Subsequently, the bromine chain end of pMA-Br was converted to an azide group by simple nucleophilic substitution reaction. ${\alpha}-Alkyn-{\omega}-bromo-functionalized$ polystyrene was also synthesized by ATRP using the alkyn-functionalized initiator, propargyl-2-bromoisobutyrate (PgBiB). In both cases, the conversion was limited to a low level to ensure a high degree of chain end functionality. Then the coupling reaction between the azide end group in $pMA-N_3$ and alkyn-functionalized PgBiB-pSt was performed by Cu(I)catalysis. This coupling reaction was monitored by gel permeation chromatography (GPC). The synthesized block copolymer was characterized by FT-IR, $^1H-NMR$ spectroscopy and $^1H-^1H$ COSY correlation spectroscopy.

• Korean Membrane Journal
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• v.10 no.1
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• pp.20-25
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• 2008

Proton conducting composite membranes were prepared by solution blending of poly(vinylidene fluoride-co-chlorotrifluoroethylene)-graft-poly(sulfopropyl methacrylate) (P(VDF-CTFE)-g-PSPMA) graft copolymer and heteropolyacid (HPA). The P(VDF-CTFE)-g-PSPMA graft copolymer was synthesized by atom transfer radical polymerization (ATRP) using direct initiation of the secondary chlorines of P(VDF-CTFE). FT-IR spectroscopy revealed that HPA nanoparticles were incorporated into the graft copolymer via hydrogen bonding interactions. The water uptake of membranes continuously decreased with increasing HP A concentration up to 45wt%, after which it slightly increased. It is presumably due to the decrease in number of water absorption sites due to hydrogen bonding interaction between the HP A particles and the polymer matrix. The proton conductivity of membranes increased with increasing HPA concentration up to 45wt%, resulting from both the intrinsic conductivity of HP A particles and the enhanced acidity of the sulfonic acid of the graft copolymer.

• Journal of the Korean Chemical Society
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• v.40 no.10
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• pp.663-669
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• 1996

The rate constants for the nucleophilic addition reactions of thioglycolic acid to vinylsulfilimine(VSI) derivatives(p-OCH3, H, p-Cl and p-Br) were determined by an ultraviolet spectrophotometric method, and rate equations which can be applied over a wide pH range were obtained. On the basis of rate equation, general base catalysis and substituent effect, a plausible addition reaction mechanism was proposed: Below pH 3.0, the reaction was proceeded via the addition of neutral molecule to carbon-carbon double bond after protonation at the nitrogen atom of the sulfilimine, and in the pH range of 3.0 to 9.0, the neutral molecule and its anion attacked to carbon-carbon double bond competitively. Above pH 9.0, sulfide anion added to the double bond (Michael type addition).

• Journal of the Korean Chemical Society
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• v.25 no.2
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• pp.110-118
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• 1981

Kinetics and mechanism for the reaction of substituted phenacyl bromides with substituted pyridines have been determined at 25, 35 and $45^{\circ}C$ in methanol and dimethylformamide by the conductivity method. The rate constants for the reaction of various pyridines with phenacyl bromide shown that electron-donating substituents in the pyridine increase the rate, while electron-attracting one decrease in both solvents. The effect of substituents in substrate, the rate being increased by electron-attracting substituents. This is as expected for nucleophilic attack of amines on the carbon atom. Isokinetic and $Br{\psi}nsted$ linear relationship were shown in the reaction of phenacyl bromide with pyridines in both solvent in which isokinetic temperature were obtained 614, $202^{\circ}K$ and ${\beta}$ values were 0.29, 0.36 in methanol and dimethylformamide respectively. In the case of the reaction of substituted phenacyl bromide with pyridines, isokinetic temperature decreases with increasing electron-attracting ability of the substituents in the phenacyl bromide, while the ${\beta}$ values were reverse. From the above results, it can be inferred that N…C bond formation decreases progressively from p-chloro- to p-methoxyphenacyl bromide and the bond formation predominates in DMF than methanol. The ${\rho}$ values of Hammett equation of the reaction of phenacyl bromide with substituted pyridines are negative in both solvent, but its value was larger negative in DMF than methanol and the ${\rho}$ value of that of substitutted substrates with pyridine was 0.3, the low value is ascribed to direct $S_N2$ attack of the nitrogen atom in pyridine ring at the methylene carbon.

• Journal of the Korean Chemical Society
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• v.28 no.5
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• pp.328-334
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• 1984

A series of phenyl N-benzenesulfonylchloroformimidate derivatives (p-H, p-Cl, p-CH3 & p-OCH3) were prepared and the hydrolysis of these compounds were studied kinetically at various pH by UV spectrophotometry in 1 ; 4 dioxane-water at $25^{\circ}C$. Hammett ${\rho}$ values measured at pH 5.0 (${\rho}$ = -0.45) and pH 10.0 (${\rho}$ = 0.40) indicate that the reaction proceeds via an azocarbonium ion intermediate in the acidic medium, whereas, it involves direct attack by hydroxide ion on the azomethine carbon atom occurs under the basic medium. The formation of stabilized azocarbonium ion species at pH 5.0 is also consistent with the large solvent effect(m = 1.3-1.5 & n = 5.0-5.5). On the basis of these findings, we may concluded that the hydrolysis of phenyl N-benzenesulfonylchloroformimidate derivatives proceeds by $SN_1$ below pH 8.0, however, above pH 10.0, the hydrolysis proceeds through $SN_2$ and in the range of pH 8.0-10.0, these two reactions occur competitively.

• Journal of the Korean Ceramic Society
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• v.30 no.4
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• pp.289-298
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• 1993

Properties in terms of the variation of the glass compositions, which were density (p), molar volume(Vm), atom/ion packing density (Dp), refractive index (nD), transformation temperature (Tg), dilatometric softening point (Td), thermal expansion coefficient (α), Young's modulus (E), and knoop hardness (KHN) were investigated in CaO-SiO2 glasses and CaO-P2O5-SiO2 glasses containing less than 10mole% of P2O5. Those properties were measured by density measurement kit, Abbe refractometer, dilatometer, ultrasonic pulse echo equipment, and micro hardness tester. When CaO content was increased in CaO-SiO2 glasses, p, Dp, nD, Tg, Td, α, E and KHN were increased, while Vm was decreased. When P2O5 was added to the CaO-SiO2 glasses with constant CaO/SiO2 ratio as 1.07, p, Dp, nD, Tg, Td, α, E and KHN were decreased, while Vm was increased. When the amount of P2O5 in glasses was kept constant, the changes of the properties with variation of CaO content in the CaO-P2O5-SiO2 glasses were very similar to those of CaO-SiO2 glasses. These phenomena could be explained by the structural role of P2O5 in the CaO-P2O5-SiO2 glasses, which was polymerization of siicate structures and resulted in [PO4] monomer structure in glasses. Due to this structural characteristics, the bond strength and packing density were changed with compositions. Proportional relationships between 1) np and Dp, 2) Tg, Td, α and CaO content, 3) E and Vm-1, and 4) KHN and P2O5 content were evaluated in this investigation.

• Korean Journal of Materials Research
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• v.23 no.5
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• pp.255-259
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• 2013

An effect of thermal annealing on activating phosphorus (P) atoms in ZnO nanorods (NR) grown using a hydrothermal process was investigated. $NH_4H_2PO_4$ used as a dopant source reacted with $Zn^{2+}$ ions and $Zn_3(PO_4)_2$ sediment was produced in the solution. The fact that most of the input P elements are concentrated in the $Zn_3(PO_4)_2$ sediment was confirmed using an energy dispersive spectrometer (EDS). After the hydrothermal process, ZnO NRs were synthesized and their PL peaks were exhibited at 405 and 500 nm because P atoms diffused to the ZnO crystal from the $Zn_3(PO_4)_2$ particles. The solubility of the $Zn_3(PO_4)_2$ initially formed sediment varied with the concentration of $NH_4OH$. Before annealing, both the structural and the optical properties of the P-doped ZnO NR were changed by the variation of P doping concentration, which affected the ZnO lattice parameters. At low doping concentration of phosphorus in ZnO crystal, it was determined that a phosphorus atom substituted for a Zn site and interacted with two $V_{Zn}$, resulting in a $P_{Zn}-2V_{Zn}$ complex, which is responsible for p-type conduction. After annealing, a shift of the PL peak was found to have occurred due to the unstable P doping state at high concentration of P, whereas at low concentration there was little shift of PL peak due to the stable P doping state.

• Journal of the Korean Chemical Society
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• v.36 no.1
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• pp.38-43
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• 1992

The Hammett's substituent constants were interpreted for substituted stilbenes by HMO method. The appropriate quantum chemical indices are chosen as independent contribution of the inductive and the resonance effects for substituent constants. It has been found that theoretical values, ${\sigma}_p{^{th}}$, defined as sum of the net charge, self atom polarizability and difference in HOMO energy between substituted- and unsubstituted-stilbenes, correlated with experimental Hammett's substituent constants. The dipole moments were found to be correlated with differences in ${\sigma}_p{^{th}}$ between two substituents for disubstituted stilbenes. It has been also found that transition optical spectra, ${\lambda}_{max}$ of the substituted stilbenes depend on difference between the HOMO and the LUMO energy as expected.