• Bulletin of the Korean Chemical Society
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• 제14권6호
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• pp.732-739
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• 1993

Good yields were usually obtained in Pd(O)-catalyzed Suzuki aryl-aryl coupling reaction, even when both coupling partners had an ortho tertiary benzamide functional group. The direct ortho functionalization of oligomeric tertiary benzamides at Snieckus condition is dependent on the chain length. Tertiary benzamide 1 can be o,o-dilithiated only by metal-halogen exchange of the 2,6-dihalo-compound. Bis-tertiary benzamide 9 can be o,o'-dilithiated with excess(4.1 equivalents) s-butyllithium/TMEDA as the lithiating agent. Tris-tertiary benzamide 21 is hard to o,o"-difunctionalize due to steric interactions among the tertiary benzamide functional groups, and due to steric interactions between these functional groups and others (if present) on the termini of the terphenyl unit.

• Bulletin of the Korean Chemical Society
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• 제10권6호
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• pp.551-554
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• 1989

Quadrupole coupling constants of $^{63}$CU in the high $T_c$ superconductor $YBa_2Cu_3O_7_{-x}$, as determined by NQR or NMR studies, are compared with the values for representative Cu(Ⅱ) complexes determined by analyzing the forbidden lines in their EPR spectra. It is shown that the two NQR lines at 22 and 31 MHz correpsond to the quadrupole coupling constants of a square planar Cu(Ⅱ) complex and a square pyramidal Cu(Ⅱ) complex, respectively.t This result is in agreement with the assignment of these lines to Cu(1) and Cu(2) sites in YBCO based on the NMR spectra of oriented single crystals.

• Bulletin of the Korean Chemical Society
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• 제6권4호
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• pp.210-214
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• 1985

Urokinase, a plasminogen activator, was conjugated with dextran by the cyanogen bromide activation-coupling method. The resulting water-soluble conjugate was purified by gel permeation chromatography on Sephadex G-200. The maximal activity was obtained when the ratio of urokinase/dextran was 1/20 for the coupling. The final preparation showed 5 CTA units/mg conjugate, 300 CTA units/mg protein, 8.4 % activity retention, and 47 % protein retention. The urokinase-dextran conjugate had good thermal, pH and storage stabilities. In addition, it showed greater resistance to the inhibitory effect of human plasma than native urokinase. Also in vitro biological half-life of urokinase increased 40 times by this conjugation. In view of activity, excellent stability and increased half-life, the conjugate can be a potential fibrinolytic agent in an injectable form.

• Bulletin of the Korean Chemical Society
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• 제10권3호
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• pp.298-302
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• 1989

The strengths of two-photon transitions from the ground state to excited vibronic states in benzene are calculated by using the CNDO/2-U wave functions. The role of vibronic coupling in two-photon absorption process is discussed. The $A_{1{\bar{g}}}-A_{2g}^+$ two-photon transitions, which are forbidden by the identity-forbidden selection rule in single frequency two-photon absorption, are too weak to be experimentally observed even when two photons of different energies are used. It is because the transitions are forbidden also by the pseudo-parity selection rule which are applicable for alternant hydrocarbons such as benzene. It is also shown that the vibronic coupling is not very effective in altering the pseudo-parity property of the electronic state. The strength of the vibronically induced two-photon absorption is strongly affected by the presence of an electronic state from which two-photon absorption can borrow the intensity. It is pointed out that the pseudo-parity selection rule may be violated in such cases.

• Bulletin of the Korean Chemical Society
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• 제19권3호
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• pp.340-344
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• 1998

A facile synthesis of 4,5-(1',2'-diphenylethylenedithio)-1,3-dithiole-2-thione (dPhEDT-DTT) is carried out via a Diels-Alder type [2+4] cycloaddition reaction of 1,3-dithiol-2,4,5-trithione oligomer and t-stilbene. Molecular structure of dPhEDT-DTT is determined by x-ray crystallography: space group P1, a=11.694(3) Å, b=12.117(3) Å, c=14.688(3) Å, α=113.12(2)°, β=102.23(2)°, γ=107.02(2)°, V= 1699.1(7) Å3, Z=2. It turns out that dPhEDT-DTT crystallizes as a racemic compound consisting of (R,R) and (S,S) enantiomers. Coupling reaction of dPhEDT-DTO undergone in neat P(OEt)3 yields TTF(SEt)4 instead of ET derivative. When PR3 (R=OEt, OPh, Ph) is used in benzene, toluene or xylene, however, dPhEDT-DTO is decomposed.

• Korean Chemical Engineering Research
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• 제50권2호
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• pp.191-197
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• 2012

Isophorone diisocyanate(IPDI), polycarbonate diol(PCD), dimethylol propionic acid(DMPA)를 출발물질로 하여 제조된 폴리우레탄 prepolymer의 미반응 NCO기를 아크릴 단량체인 pentaerythritol triacrylate(PETA)로 capping시켜 acrylic terminated polyurethane prepolymer를 합성하였다. 그 후 이 prepolymer의 잔여 NCO기를 실란커플링제인 aminopropyl triethoxysilane(APS) 또는 glycidoxypropyl trimethoxysilane(GPTMS)와 반응시켜 silylated acrylic terminated waterborne polyurethane을 제조하였다. 동적 빛 산란법에 의해 측정된 순수한 수분산 폴리우레탄의 평균 직경은 PETA와 APS가 첨가됨에 따라 14.3 nm에서 208.6 nm로 크게 증가하였다. 또한 silylated acrylic terminated waterborne polyurethane 코팅 도막의 연필경도 및 내마모성은 순수한 수분산 폴리우레탄보다 우수하였다.

• Bulletin of the Korean Chemical Society
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• 제23권5호
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• pp.769-772
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• 2002

• 한국자기공명학회논문지
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• 제10권1호
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• pp.1-37
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• 2006

General expressions for solid state NMR lines are described for transitions under static, magic angle spinning, and variable angle spinning conditions in the case where the principal axis system for the anisotropic chemical shift tensor is noncoincident with that of the quadrupole coupling tensor. It is demonstrated that solid state NMR powder pattern simulation program VMAS based on the conventional grid point method of integrating over the Euler angle space is fast enough in comparison with the POWDER simulation package and Gauss-point method.

• 생약학회지
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• 제8권1호
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• pp.23-29
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• 1977

The $^{13}C-chemical\;shifts$ of the phenolic coumarine derivatives, aesculetin, daphnetin and herniarin were studied on the basis of my previous report. All spectral data found in this report could be utilized to the structure elucidation of the unknown phenolic coumarine derivatives and other phenolic compounds. In addition, it is suggested that a long range coupling may occur in the following structure as represented by arrow.

• 대한화학회지
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• 제34권6호
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• pp.646-651
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• 1990

L-serine으로부터 합성한 2-amino-3-(diethylphosphono)propionic acid methyl ester를 아미노산과 축합시켜 광학 활성을 가지는 포스포노디펩티드를 합성하였다.