• 분석과학
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• 제14권2호
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• pp.159-166
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• 2001

한외여과법을 이용하여 휴믹산(Aldrich Co.)을 분자량 별로 3개의 소부분($F_1$: 1,000-10,000 daltons; $F_2$: 10,000-50,000 daltons; $F_3$: 100,000-300,000 daltons)으로 분리한 뒤, 적외선 분광법과 고체상태 C-13 핵자기공명 분광법을 이용하여 각 소부분의 구조적 특성을 규명하였고, pH 적정법을 이용하여 각 소부분의 카르복실산 작용기 함량을 결정하였다. 휴믹산과 금속이온과의 착물 반응 특성을 규명하기 위하여, Eu(III)과 각 소부분 휴믹산과의 착화합물($[Eu(III)]=1.0{\times}10^{-4}mol\;L^{-1}$, $(HA)=470-970mg\;L^{-1}$, at pH 5.0)을 Eu(III)의 $^7F_0-{^5}D_0$ 전이를 이용한 여기 스펙트럼으로 관찰하였다. 적외선 스펙트럼과 C-13 핵자기공명 스펙트럼 분석 결과, 100,000 dalton 이상의 고분자량의 휴믹산 분자는($F_3$) 높은 지방족 탄소함량을 가지며, 50,000 daltons 이하의 저 분자량의 휴믹산($F_1$, $F_2$) 분자는 상대적으로 높은 방향족 탄소 함량을 가짐을 확인하였다. pH 적정 결과 휴믹산은 분자의 크기가 커질수록 더 낮은 카르복실기 함량을 가짐을 확인하였다. Eu(III)-휴믹산 착물의 여기스펙트럼을 Lorenzian-Gaussian 식을 이용하여 분석한 결과, 휴믹산 분자의 크기가 커질수록 최대피크의 파장 위치가 더 낮은 에너지 방향으로 이동하였다. 이러한 피크 이동의 결과는 휴믹산 분자의 크기가 커질수록 Eu(III)과 결합하는 분자내 카르복실산의 배위수가 증가함을 나타내는 것으로서, C-13 NMR 스펙트럼 분석에서 밝혀진 휴믹산 분자의 구조적인 요인과의 관련성을 밝혔다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.251.2-251.2
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• 2010

Plant biomass has been proposed to be an alternative source for petroleum-based chemical compounds. Especially, phenolic chemical compounds can be obtained from lignin by chemical depolymerization processes because lignin consists of complex aromatic polymer such as trans-p-coumaryl, coniferyl and sinapyl alcohols, etc. Phenolic chemical compounds from lignin were usually produced in super critical water. However, we applied Near-critical water (NCW) system because NCW is known as a good solvent for lignin depolymerization. Organic matter like lignin can be solved in NCW system and the system has a unique acid-base property without conventional non-eco-friendly chemicals such as sulfuric acid and sodium hydroxide. In this work, we tried to optimize the NCW depolymerization system by adjusting the processing variables such as reaction time, temperature and pressure. Moreover, the amount of additional phenol was optimized by changing the molar ratio between water and phenol. Phenol was used as capping agent to prevent re-polymerization of active fragment such as formaldehyde. Alkali-lignin was used as a starting material and characterized by a Solid State 13C-NMR, FT-IR and EA (Elemental Analysis). GC-MS analysis confirmed that o-cresol, p-cresol, anisole and 4-hydroxyphathalic acid were the main product and they were quantitatively analyzed by HPLC.

• Bulletin of the Korean Chemical Society
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• 제32권spc8호
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• pp.3031-3038
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• 2011

Ion-coordinating ruthenium complexes [cis-Ru(dcbpy)(L)(NCS)$_2$, where dcbpy is 4,4'-dicarboxylic acid-2,2'-bipyridine and L is 1,4,7,10-tetraoxa-13-azacyclopentadecane, JK-121, or bis(2-(2-methoxy-ethoxy)ethyl) amine, JK-122] have been synthesized and characterized using $^1H$ NMR, Fourier transform IR, UV/vis spectroscopy, and cyclic voltammetry. The effect of $Li^+$ in the electrolyte on the photovoltaic performance was investigated. With the stepwise addition of $Li^+$ to a liquid electrolyte, the device shows significant increase in the photo-current density, but a small decrease in the open circuit voltage. The solar cell with a hole conductor, the addition of $Li^+$ resulted in a 30% improvement in efficiency. The JK-121 sensitized cells in the liquid and solid-state electrolyte give power conversion efficiencies of 6.95% and 2.59%, respectively, under the simulated sunlight.

• Bulletin of the Korean Chemical Society
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• 제34권9호
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• pp.2583-2588
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• 2013

A new type of solid and gel-state ionics based on siloxane pyridinium iodides was synthesized and used as electrolytes in dye-sensitized solar cells. The resulting electrolytes were characterized by $^1H$ NMR spectroscopy, TGA and diffusion coefficient. The synthesized siloxane pyridinium iodide electrolytes have characteristics of different chain length of siloxane moieties. The ion conductivities were given 2.7-3.2 S/cm. Among the three SiDPIs based electrolytes, DSSC employing the SiDPI2 gives an open circuit voltage of 0.704 V, a short-circuit current of 15.85 $mA/cm^2$ and conversion efficiency of 6.8% under light intensity of 100 $mW/cm^2$. In addition, the performance of the DSSCs showed relatively reasonable compared with the propylpyridinium iodide (PPI) electrolyte.

• Macromolecular Research
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• 제17권5호
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• pp.301-306
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• 2009

This work has demonstrated that a novel amphiphilic poly(epichlorohydrine)-graft-polystyrene (PECH-g-PS) copolymer at 34:66 wt% was synthesized via atom transfer radical polymerization (ATRP) of styrene using PECH as a macroinitiator. The structure of the graft copolymer was characterized by nuclear magnetic resonance ($^1H$ NMR) and FTIR spectroscopy, demonstrating that the "grafting from" method using ATRP was successful. The self-assembled graft copolymer was used as a template film for the in-situ growth of silver nanoparticles from $AgCF_3SO_3$ precursor under UV irradiation. The in situ formation of silver nanoparticles with 6-8 nm in average size in the solid state template film was confirmed by transmission electron microscopy (TEM), UV-visible spectroscopy and wide angle X-ray scattering (WAXS). Differential scanning calorimetry (DSC) also displayed the selective incorporation and the in situ formation of silver nanoparticles within the hydrophilic PECH domains, probably due to stronger interaction of the silvers with the ether oxygens of PECH backbone than that with hydrophobic PS side chains.

• Journal of Microbiology and Biotechnology
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• 제17권10호
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• pp.1598-1606
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• 2007

A new series comprising 7 analogs of N-(sulfanyl ethanoyl)-L-HSL derivatives, 2 analogs of N-(fluoroalkanoyl)-$_L$-HSL derivatives, N-(fluorosulfonyl)-L-HSL, and 2,2-dimethyl butanoyl HSL were synthesized using a solid-phase organic synthesis method. Each of the 11 synthesized compounds was analyzed using NMR and mass spectroscopies, and molecular modeling studies of the 11 ligands were performed using SYBYL packages. Thereafter, a bacterial test was designed to identify their quorum-sensing inhibition activity and antifouling efficacy. Most of the synthesized compounds were found to be effective as quorum-sensing antagonists, where antagonist screening revealed that 10 among the 11 synthesized ligands were able to antagonize the quorum sensing of A. tumefaciens.

• 한국응용과학기술학회지
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• 제15권4호
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• pp.57-62
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• 1998

In this study, a new conducting materials, namely, a Schiff base (polymeric azomethine) was synthesized from 2,6-diamino-N-docosyl pyridinium bromide and terephthalaldehyde to obtain a soluble and fusible conducting polymer. The synthesized Schiff base structure was analyzed by using UV/vis absorption spectrophotometer, FT-IR spectrometer and $^1H$-NMR spectrometer. It was found that the Schiff base was successfully synthesized and soluble in carbon tetrachloride$(CC^{14})$, its Langmuir-Blodgett film was easily fabricated, and its surface pressure was determined to be 30mN/m for solid state by measuring ${\pi}$-A isotherm.

• 한국자기공명학회논문지
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• 제15권2호
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• pp.175-186
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• 2011

Amyloid fibrils have long been known to be the well known ${\alpha}$-helix to ${\beta}$-sheet transition characterizing the conversion of cellular to scrapie forms of the prion protein. A very short sequence of Yeast prion-like protein, GNNQQNY (SupN), is responsible for aggregation that induces diseases. KSI-fused tandem repeats of SupN vector are constructed and used to express SupN peptide in Escherichia coli (E.Coli). A method for a production, purification, and cleavage of tandem repeats of recombinant isotopically enriched SupN in E. coli is described. This method yields as much as 20 mg/L of isotope-enriched fusion proteins in minimal media. Synthetic SupN peptides and $^{13}C$ Gly labeled SupN peptides are studied by Congo Red staining, Birefringence and transmission electron microscopy to characterize amyloid fibril formation. To get a better understanding of aggregation-structure relationship of 7 residues of Yeast prion-like protein, the change of a conformational structure will be studied by $^{13}C$ solid-state nmr spectroscopy as powder of both amorphous and fibrillar forms.

• Advances in nano research
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• 제2권2호
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• pp.77-88
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• 2014

Solvothermal treatment of late transition metal acetylacetonates in a novel medium composed either of pure acetophenone or acetophenone mixtures with amino alcohols offers a general approach to uniform hydrophilic metal nanoparticles with high crystallinity and low degree of aggregation. Both pure metal and mixed-metal particles can be accesses by this approach. The produced materials have been characterized by SEM-EDS, TEM, FTIR in the solid state and by Nanoparticle Tracking Analysis in solutions. The chemical mechanisms of the reactions producing nanoparticles has been followed by NMR. Carrying out the process in pure acetophenone produces palladium metal, copper metal with minor impurity of $Cu_2O$, and NiO. The synthesis starting from the mixtures of Pd and Ni acetylacetonates with up to 20 mol% of Pd, renders in minor yield the palladium-based metal alloy along with nickel oxide as the major phase. Even the synthesis starting from a mixed solution of $Cu(acac)_2$ and $Ni(acac)_2$ produces oxides as major products. The situation is improved when aminoalcohols such as 2-aminoethanol or 2-dimethylamino propanol are added to the synthesis medium. The particles in this case contain metallic elements and pairs of individual metals (not metal alloys) when produced from mixed precursor solutions in this case.

• E2M - 전기 전자와 첨단 소재
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• 제9권4호
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• pp.404-409
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• 1996

The structural and electric properties of $Y_{1-x}$YbF$_{x}$Ba$_{2}$Cu$_{3}$O$_{7-y}$(x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) have been investigated by using XRD(X-ray diffraction), TMA(thennomechanical analysis), NMR(nuclear magnetic resonance) analysis and four probe method. $Y_{1-x}$YbF$_{x}$Ba$_{2}$Cu$_{3}$O$_{7-y}$ samples were prepared by conventional solid-state reaction method using $Y_{2}$O$_{3}$, BaCO$_{3}$, CuO and YbF$_{3}$ power. TMA and high temperature XRD results shows that orthorhombic to tetragonal phase transition occurs in the unfluorinated 1-2-3 sample while the phase change is not observed in the fluorinated 1-2-3 samples. Superconducting transition temperature(T$_{c}$) increases with increasing YbF$_{3}$ content ; T$_{c}$, of the sample reaching maximum of 102K for x=0.3, and then decreases with further increasing YbF$_{3}$ content. The structural analysis and T$_{c}$ results shows that the fluorine doping stabilize the orthorhombic phase, together with the increase in T$_{c}$.}$ c/.TEX> c/.