• Bulletin of the Korean Chemical Society
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• 제1권3호
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• pp.109-112
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• 1980

Ultraviolet spectrophotometric investigations were carried out on monoalkylbenzene-iodine systems in carbon tetrachloride. The results reveal the formation of one-to-one molecular complexes. On the basis of the equilibrium constants for these complexes of representative monosubstituted benzenes, the following order of increasing stability is obtained: i-propyl- ${\Delta}$H, ${\Delta}$G and ${\Delta}$S for the interaction of a number of monoalkyl substituted benzenes with iodine have been determined. In general, it can be said that as ${\Delta}$H becomes increasingly negative, corresponding decreases in the ${\Delta}$G and the ${\Delta}$S values are observed, and these variations are linear. The thermodynamic constants become increasingly negative with increasing monoalkyl substitution of the aromatic donor nucleus. The complex bond is therefore weak, and its formation is accompanied by relatively small entropy changes. Thus, analysis of these findings is discussed.

• Bulletin of the Korean Chemical Society
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• 제13권5호
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• pp.507-511
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• 1992

Six-coordinate molybdenum(V) complexes X[MoO$(NCS)_2$(L)], where X=$PyH^+$, $Me_4N^+$, $Et_4N^+$, n-$Bu_4N^+$, and L= the tridentate schiff base dianions derived from the condensation reaction between various salicylaldehydes and 2-aminophenol have been synthesized. The complexes have been characterized by elemental analysis, conductivity, UV-visible, IR, $^1H$-NMR, and mass spectroscopy. The coordination around the molybdenum appears to be distorted octahedral. A tridentate ligand containing the ONO donor atoms occupies meridional positions with the N atom trans to the terminal oxo group. Two NCS ligands bond to the molybdenum through the N atom and are cis to the Mo = $O_t$ group. The electrochemical behaviors of the complexes have also been investigated by cyclic voltammetry in dimethylsulfoxide.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2004년도 추계학술발표회 논문집
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• pp.274-275
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• 2004

The majority of dyes belong to the chromophoric class known as donor-acceptor systems, the essential structural feature of such systems being the presence of one or more electron donating groups conjugated to one or more electron withdrawing groups via an unsaturated bridge. The indigo molecule may be formally divided into two identical electron donor/acceptor subsystems, each containing an add number of pi electrons, two subsystems being joined by carbon-carbon double bond. Indigoid type dyes which show a strong colour change on protonation or dissociation have many potential functional applications, for example as analytical pH indicators, solvent polarity indicators, and in various imaging and reprographic systems.

• Applied Biological Chemistry
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• 제50권3호
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• pp.187-191
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• 2007

벼잎집무늬마름병균(RS: Rhizoctonia solani) 및 고추역병균 (PC: Phytophtora capsici)에 대한 N-phenyl-O-phenylthionocarbamate 유도체 중, N-phenyl 치환체(X)들의 살균활성에 관한 비교분자 유사성 지수분석(CoMSIA) 모델을 유도하고 기질분자와 ${\beta}-tubulin$ 사이의 수소결합성을 정량적으로 검토하였다. CoMSIA 모델들의 기여도로부터 두 균주에 대한 살균활성은 공통적으로 수소결합 받게장이 가장 크게 기여하였다. 두 균주 사이의 살균활성에 있어서 선택성은 N-phenyl 고리상 para- 및 meta-치환기로서, RS에서는 수소결합 주게가 아닌 작용기를 그리고 PC에서는 수소결합 받게가 아닌 작용기들의 역할에 기인하는 것으로 예측된다. 또한, RS에서는 meta-위치에 입체적으로 작고 음하전을 선호하는 치환기(X)가 그리고 PC에서는 para-위치에 수소결합 받게가 도입된다면 두 균주에 대한 살균 활성이 증가 할 것이다.

• Bulletin of the Korean Chemical Society
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• 제18권10호
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• pp.1090-1093
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• 1997

The solvent effects on the isotropic NMR shifts in conformationally rigid ligands such as quinuclidine, pyridine, and 4-aminopyridine coordinated to the paramagnetic polyoxometalate, [SiW11CoⅡO39]6- (SiW11Co), are reported. For these complexes the ligand exchange is slow on the NMR time scale and pure 1H NMR signals have been observed at room temperature. The signals for the SiW11Co complexes are shifted upfield whe dimethyl sulfoxide-d6 (DMSO) is added to a D2O solution. The isotropic shifts are separated into contact and pseudocontact contributions by assuming that the contact shifts are proportional to the isotropic shifts of the same ligands coordinated to [SiW11NiⅡO39]6-. It is shown that both the contact and pseudocontact shifts decrease (the absolute values of the pseudocontact shifts increase), when D2O is replaced by DMSO. It is suggested that D2O, a strong hydrogen bond donor, withdraws electron density from [SiW11CoⅡO39]6-, increasing the acidity of the cobalt ion toward the axial ligand. When D2O is replaced by DMSO, the acidity of the cobalt ion in SiW11Co decreases, weakening the Co-N bond. Then both the contact and pseudocontact shifts are expected to decrease in agreement with the observed solvent effects.

• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3629-3634
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• 2012

A series of new 4-(pyridin-4-yl)-(3-methoxy-5-methylphenyl)-1H-pyrazoles (6a-k & 7a-l) has been rationally designed based on the structure of the lead compound KIST301080, a selective ROS receptor tyrosine kinase inhibitor, in order to study the activity of ROS of this new class of inhibitors. The compounds were synthesized and screened against ROS kinase, where compound 6h showed moderate inhibitory activity with an $IC_{50}$ value of $6.25{\mu}M$. The study emphasized the importance of the acetonitrile group at the pyrazole ring and also the importance of having a hydrogen bond donor on the distal phenyl ring linked to the pyridine moiety.

• Bulletin of the Korean Chemical Society
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• 제11권1호
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• pp.49-54
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• 1990

The gas-phase thermolysis reactions of ${\alpha}$- and ${\beta}$-methylated ethyl formates, Y = $CH-X-CHR_1CH_2R_2$ where X = Y = O or S and $R_1\;=\;R_2$ = H or $CH_3$, are investigated theoretically using the AM1 method. The experimental reactivity order is reproduced correctly by AM1 in all cases. The thermolysis proceeds through a six-membered cyclic transition state conforming to a retro-ene reaction, which can be conveniently interpreted using the frontier orbital theory of three-species interactions. The methyl group substituted at $C_{\alpha}\;or\;C_{\beta}$ is shown to elevate the ${\pi}$-HOMO of the donor fragment (Y = C) and depress the ${\sigma}^{\ast}$-LUMO of the acceptor fragment ($C_{\beta}$-H), increasing the nucleophilicity of Y toward ${\beta}$-hydrogen which in turn increases the reactivity. The two bond breaking processes of the $C_{\alpha}$-X and $C_{\beta}$-H bonds are concerted but not synchronous so that the reaction takes place in two stages as Taylor suggested. The initial cleavage of $C_{\alpha}$-X is of little importance but the subsequent scission of $C_{\beta}$-H occurs in a rate determining stage.

• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2592-2596
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• 2012

Cysteine capped silver nanoparticles (Cys-AgNPs) have been synthesized by employing electrochemically active biofilm (EAB), $AgNO_3$ as precursor and sodium acetate as electron donor in aqueous solution at $30^{\circ}C$. Cys-AgNPs of 5-10 nm were synthesized and characterized by UV-Vis, FT-IR, XRD and TEM. Capping of the silver nanoparticles with cysteine provides stability to nanoparticles by a thiolate bond between the amino acid and the nanoparticle surface and hydrogen bonding among the Cys-AgNPs. In addition, the antibacterial effects of as-synthesized Cys-AgNPs have been tested against two pathogenic bacteria Escherichia coli (O157:H7) and Pseudomonas aeruginosa (PAO1). The results demonstrate that the as-synthesized Cys-AgNPs can proficiently inhibit the growth and multiplication of E. coli and P. aeruginosa.

• Bulletin of the Korean Chemical Society
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• 제3권1호
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• pp.9-13
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• 1982

Sulfametrole, $C_9H_{10}N_4O_3S_2$, crystallizes in the monoclinic system, space group $P2_1/n$ , with a = 8.145(2), b = 16.505(4), c = 9.637(1)${\AA},{\beta}=103.72(1)^{\circ},D_m=1.52gcm^{-3}$,Z=4.Intensities for 3594(2143 observed) unique reflections were measured on a four-circle diffractometer with Mo $K{\alpha}$ radiation $({\lambda}=0.71069{\AA})$. The structure was solved by direct method and refined by full-matrix least squares to a final R of 0.070. The geometrical features of the thiadiazole ring indicate some ${pi}$-electron delocalization inside the ring. The least squares planes defined by the benzene and thiadiazole rings are nearly perpendicular to each other(dihedral angle; $93.9^{\circ}$ ). All the potential hydrogen-bond donor atoms in the molecule, N(1) and N(2), are included in the hydrogen bonding. The molecules through hydrogen bonding form three dimensional network.

• Bulletin of the Korean Chemical Society
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• 제1권2호
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• pp.62-68
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• 1980

Ultraviolet spectrophotometric investigations have been carried out the systems of monoalkylbenzene with iodine in carbon tetrachloride. The results reveal the formation of one to one molecular complexes. The equilibrium constants for these complexes of representative monosubstituted benzene reveal the following order of increasing stability: benzene < methyl- < ethyl- < n-propyl-benzene. The value of ${\Delta}H$, ${\Delta}G$, and ${\Delta}S$ for interaction of a number of monoalkyl substituted benzene with iodine has been determinated. In general, as ΛH becomes increasingly negative, corresponding decreases in ${\Delta}G$ and ${\Delta}S$ values are observed, and these variation are linear. The thermodynamic constants become increasingly negative with increasing monoalkyl substitution of the aromatic donor nucleus. The complex bond is therefore weak, and its formation is accompanied by relatively small entropy changes.