• 대한화학회지
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• 제58권2호
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• pp.234-238
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• 2014

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2165-2166
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• 2011

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2001년도 한국우주과학회보 제10권1호
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• pp.38-38
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• 2001

No Abstract, See Full Text

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2016년도 자성 및 자성재료 국제학술대회
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• pp.19-19
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• 2016

• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2731-2736
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• 2012

The use of pyrimethamine as antibacterial drug is limited by the poor solubility. To enhance its solubility, we prepared complexes of pyrimethamine with low-molecular-weight succinoglycan isolated from Sinorhizobium meliloti. Low-molecular-weight succinoglycans are monomers, dimers, and trimers of the succinoglycan repeating unit. The monomers and dimers were separated into their three species (M1, M2, and M3) and four fractions (D1 to D4) using chromatographic techniques, which were shown to be nontoxic. The solubility of pyrimethamine was markedly increased up to 42 fold by succinoglycan D3, where the level of its solubility enhancement was even 8-20 fold higher comparing with cyclodextrin or its derivatives. The complex formation of succinoglycan D3 with pyrimethamine was confirmed by $^1H$ nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy, and molecular modeling studies. Herein, we suggest that the low-molecular-weight succinoglycans may be utilized as highly effective solubilizers of pyrimethamine for pharmaceutical purposes.

• 대한화학회지
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• 제55권3호
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• pp.392-399
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• 2011

벤조산 유도체($NH_2$, OH, H, F, Cl, CN, NO, $NO_2$) 의 두 형태를 6-311++G(d,p) 바탕 집합을 이용하여 MP2, DFT 및 HF 수준으로 연구하였으며, cis이성 질체가 더 안정하였다. 벤조산의 수소 결합 형성은 안정화 에너지를 이용하여 추산하였으며, 이합체에 대한 수소결합 에너지 계산치는 고리에서 협동 상호작용이 일어남을 보여주었다. 페닐 고리로 전자를 밀어내는 그룹(ERG)은 더 안정한 수소 결합이 형성하였다. 이합체에서 O-H 결합의 적색이동은 -565.3에서 $-589.3\;cm^{-1}$ 범위였으며, 상호 작용의 특성은 NBO 분석을 이용하여 연구하였다.

• Bulletin of the Korean Chemical Society
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• 제34권5호
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• pp.1414-1420
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• 2013

Five novel spiro[benzo[c]fluorene-7,9'-fluorene] based dyes, including 5-[spiro[benzo[c]fluorene-7,9'-fluoren]-5-yl] spiro[benzo[c]fluorene-7,9'-fluorene] (7), 5-[spiro[benzo[c]fluorene-7,9'-fluoren]-9-yl] spiro[benzo[c]fluorene-7,9'-fluorene] (8), 5-[spiro[benzo[c]fluorene-7,9'-fluoren]-2'-yl] spiro[benzo[c]fluorene-7,9'-fluorene] (9), 9-[spiro[benzo[c]fluorene-7,9'-fluoren]-9-yl] spiro[benzo[c]fluorene-7,9'-fluorene] (10), and 2'-[spiro[benzo[c]-fluorene-7,9'-fluoren]-2'-yl] spiro[benzo[c]fluorene-7,9'-fluorene] (11) were successfully prepared from the corresponding halogen and boronic acid derivatives through the Suzuki coupling reaction, respectively. Chemical structures were confirmed by $^1H$ nuclear magnetic resonance (NMR), $^{13}C$ NMR, Fourier transforminfrared spectrscopy, mass spectroscopy, and elemental analysis. The thermal properties were determined by differential scanning calorimetry and thermal gravimetric analysis. The relationships between the optical and electrochemical properties and the combined positions between these dimers were systematically investigated using UV-vis, photoluminescence (PL), and photoelectron spectroscopy. These five dimers exhibited high fluorescent quantum yields and good morphological stability with high glass transition states > $174^{\circ}C$. Dimer 7 showed a UV absorbance peak at 353 nm, emission PL peak at 424 nm, and quantum efficiency of 0.62 in a cyclohexane solution.

• Mass Spectrometry Letters
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• 제13권4호
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• pp.177-183
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• 2022

The monomer and dimer structures of the amyloid fragment Aβ(1-16) sequence formed in H₂O were investigated using electrospray ionization mass spectrometry (MS) and tandem MS (MS/MS). Aβ16 monomers and dimers were indicated by signals representing multiple proton adduct forms, [monomer+zH]ⁿ⁺ (=M^z+, z = charge state) and [dimer+zH]^z+ (=D^z+), in the MS spectrum. Fragment ions of monomers and dimers were observed using collision-induced dissociation MS/MS. Peptide bond dissociation was mostly observed in the D1-D7 and V11-K16 regions of the MS/MS spectra for the monomer (or dimer), regardless of the monomer (or dimer) charge state. Both covalent and non-covalent bond dissociation processes were indicated by the MS/MS results for the dimers. During the non-covalent bond dissociation process, the D³⁺ dimer complex was separated into two components: the M¹⁺ and M²⁺ subunits. During the covalent bond dissociation of the D³⁺ dimer complex, the b and y fragment ions attached to the monomer, (M+b_10-15)^z+ and (M+y_9-15)^z+, were thought to originate from the dissociation of the M²⁺ monomer component of the (M¹⁺+M²⁺) complex. Two different D³⁺ complex geometries exist; two distinguished interaction geometries resulting from interactions between the M¹⁺ monomer and two different regions of M²⁺ (the N-terminus and C-terminus) are proposed. Intricate fragmentation patterns were observed in the MS/MS spectrum of the D⁵⁺ complex. The complicated nature of the MS/MS spectrum is attributable to the coexistence of two D⁵⁺ configurations, (M¹⁺+M⁴⁺) and (M²⁺M³⁺), in the Aβ16 solution.

• 한국식품과학회지
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• 제28권3호
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• pp.446-450
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• 1996

Methyl linoleate의 중합체 형성에 미치는 온도의 영향을 조사하기 위해 산소를 주입하인서 $60^{\circ}C,\;90^{\circ}C,\;120^{\circ}C,\;150^{\circ}C$)에서 산화시켰다. 각 온도에서 시간에 따른 과산화물가의 변화 곡선을 기초로하여 각 온도에서 4가지의 산화 시간을 선정하였다. 중합체 함량 및 중합체 결합 특성은 High Performance Size Exclusion Chromatography로 분석하였다. 각 온도에서 만화 시간에 따른 총 산화물 함량과 중함체 함량사이에는 높은 상관관계를 나타냈다. 모든 온도에서 생성된 중합체는 이중체로 확인되었으며, $60^{\circ}C$와 $90^{\circ}C$에서는 C-O-O-C 결합상태인 이중체를 확인할 수 있었으나, $120^{\circ}C$와 $150^{\circ}C$에서는 C-O-O-C결합형태를 갖는 이중체는 확인할 수 없었다. 따라서 $120^{\circ}C$와 $150^{\circ}C$에서 생성된 이중체는 C-O-C/C-C결합 형태인 것으로 추정되었다. 또한, C-O-O-C결합 형태의 이중체는 $60^{\circ}C$보다는 $9^{\circ}C$에서 보다 쉽게 파괴되는 경향을 나타냈다.

• Bulletin of the Korean Chemical Society
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• 제27권8호
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• pp.1249-1252
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• 2006