• Carbon letters
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• 제22권
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• pp.60-69
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• 2017

Nitrogen-doped carbon nanosheets with a developed porous structure were prepared from polyurethane foams by hydrothermal carbonization following $ZnCl_2$ chemical activation. Scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, solid state $^{13}C$ nuclear magnetic resonance (NMR) spectra and X-ray photoelectron spectroscopy were used to characterize the nitrogen-doped carbon nanosheet structure and composition. The removal of Cr(VI) by the N-doped carbon nanosheets was investigated. The results showed that the maximum removal capacity for chromium of 188 mg/g was found at pH=2.0 with PHC-Z-3. pH had an important effect on Cr(VI) removal and the optimal pH was 2.0. Moreover, amino groups and carboxyl groups in the nitrogen-doped carbon nanosheet played important roles in Cr(VI) removal, and promoted the reduction of Cr(VI) to Cr(III).

• Bulletin of the Korean Chemical Society
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• 제35권7호
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• pp.2009-2012
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• 2014

An anionic surfactant, sodium dodecylbenzene sulfonate (SDBS), was introduced during the ultrasonication process for exfoliation of graphene. The surfactant plays the roles of exfoliator and stabilizer by binding to the graphene surface. The obtained modified graphene was characterized by Fourier-transform infrared spectroscopy (FT-IR) and solid state $^{13}C$ CP/MAS NMR to analyze the binding between molecules, and by X-ray diffraction (XRD) to characterize the bulk structure. The resulting graphene exhibited good dispersion stability in both water and organic solvents.

• Bulletin of the Korean Chemical Society
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• 제25권3호
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• pp.351-356
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• 2004

Selected MPEG-b-PDLLA block copolymers have been synthesized by ring-opening polymerization with systematic variation of the chain lengths of the resident hydrophilic and hydrophobic blocks. The size and shape of the micelles that spontaneously form in solution are then controlled by the characteristics of the block copolymer template. All the materials prepared in this study showed the tunable pore size of 20-80 ${\AA}$ with the increase of hydrophobic chain lengths and up to 660 $m^2$/g of specific surface area. The formation mechanism of these nanoporous structures obtained by controlling the micelle size has been confirmed using both liquid and solid state $^{13}C\;and\;^{29}Si$ NMR techniques. This work verifies the formation mechanism of nanoporous structures in which the pore size and wall thickness are closely dependent on the size of hydrophobic cores and hydrophilic shells of the block copolymer templates.

• 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.

• 공업화학
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• 제4권2호
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• pp.403-408
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• 1993

키틴과 프로필렌 옥시드를 반응시켜 히드록시프로필 키틴(HPCH)을 얻었고 할로겐화 유기용매내에서 HPCH의 액정형성능을 관찰하였다. 키틴과 HPCH의 고체 $^{13}C$ NMR 스펙트럼 분석 결과 히드록시프로필기의 도입을 확인하였다. 원소분석결과 히드록시프로필기의 치환도는 0.8정도였다. WAXD패턴 측정결과 키틴에 히드록시프로필기가 도입됨에 따라 결정성은 감소하였고 유기용매에 대한 용해도는 증가하였다. HPCH를 디클로로아세트산과 1, 2-디클로로에탄 혼합용매에 녹여 편광현미경으로 관찰한 결과 25% 이상의 용액농도에서 콜레스테릭 액정상에서 전형적으로 관측되는 지문영역이 나타남을 알 수 있었다. 용액의 점도는 시간변화에 따라 감소함을 알 수 있었다.

• 폴리머
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• 제37권6호
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• pp.777-783
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• 2013

본 연구에서는 실리카 나노입자를 dipodal 형태의 bis[3-(trimethoxysilyl)propyl]amine(BTMA) 실란 커플링제로 실리카 표면을 개질한 후, glycidyl methacrylate(GMA)로 표면 처리를 하여 실리카에 결합된 BTMA의 N-H기와 GMA의 epoxide기의 개환 반응에 의하여 실리카 표면에 중합용 methacrylate기를 도입하는 연구를 수행하였다. 반응시간, 반응온도 및 투입하는 GMA의 농도 변화가 BTMA의 N-H기와 GMA의 epoxide기 사이의 반응에 미치는 영향을 Fourier transform infrared spectroscopy(FTIR), elemental analysis(EA) 및 고체상태 $^{13}C$ cross-polarization magic angle spinning(CP/MAS), nuclear magnetic resonance spectroscopy(NMR)법을 사용하여 분석하였다. BTMA로 개질된 실리카를 GMA로 처리하면 실리카 입자에 결합되어 있는 BTMA의 N-H기와 GMA의 epoxide기가 열리면서 상호 반응이 일어났으며, 실험한 조건에서는 반응시간, 반응온도 및 투입하는 GMA 농도가 증가할수록 실리카 표면에 도입되는 methacrylate기가 증가함을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제24권5호
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• pp.605-609
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• 2003

The lower-order lithium organocyanocuprate compound, (THF)₃Li(NC)Cu($C_6$H₃-2,6-Mes₂) (1), and the bulky terphenyl Grignard reagent, Br(THF)₂Mg($C_6$H₃-2,6-Trip₂) (2), have been synthesized and structurally characterized both in the solid state by single crystal x-ray crystallography and in solution by multi-nuclear NMR and IR spectroscopy. The compound (1) was isolated as a monomeric contact ion-pair in which the C (organic ipso)-Cu-CN-Li atoms are coordinated linearly. The lithium has a tetrahedral geometry as a result of solvation by three THF molecules. The compound (1) is the first example of fully characterized monomeric lower order lithium organocyanocuprate. The bulky Grignard reagent (2) was also isolated as a monomer in which the magnesium, solvated by two THF molecules, has a distorted tetrahedral geometry. The crystals of (1) possess triclinic symmetry with the space group $P{\={1}}$, Z = 2, with a = 12.456(3) Å, b = 12.508(3) Å, c = 13.904(3) Å, α = 99.81°, β = 103.72(3)°, and γ = 119.44(3)°. The crystals (2) have a monoclinic symmetry of space group $P2_{1/C}$, Z = 4, with a = 13.071(3) Å, b = 14.967(3) Å, c = 22.070(4) Å, and β = 98.95(3)°.

• 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.

• Korean Chemical Engineering Research
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• 제49권6호
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• pp.865-868
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• 2011

배가스로부터 이산화탄소의 분리 특성을 파악하기 위해 유기 화합물인 하이드로퀴논을 이용하여 크러스레이트 화합물을 형성하였다. 형성된 크러스레이트 화합물은 고체 NMR 및 라만 분광법을 이용하여 기체의 포집 거동을 확인하였으며, 기체 분리 효율을 계산하기 위하여 원소 분석기를 통한 정량분석도 함께 수행하였다. 분석 결과 배가스에 포함된 이산화탄소는 질소에 비해 동일한 조건에서 크러스레이트 화합물 내로 더 잘 포집되는 것으로 확인되었다. 또한 다양한 압력에서 형성된 시료들을 분석한 결과, 이러한 이산화탄소의 선택적 포집 특성이 매우 낮은 압력에서도 뚜렷한 것으로 확인되어 추가적인 에너지 소모를 적게 하면서도 배가스로부터 이산화탄소를 대규모로 분리/회수하는 것이 가능할 것이라 판단된다. 본 연구에서 얻어진 결과는 향후 배가스에 대한 분리 응용 기술이나 혼합 가스의 선택적 분리와 같은 분야에서 중요한 정보를 제공할 수 있을 것으로 기대된다.

• 대한화학회지
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• 제65권2호
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• pp.93-105
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• 2021

Mononuclear Cu(II), Ni(II), Co(II), Mn(II), Zn(II), Fe(III), Ru(III), and UO2(II) complexes of 2-hydroxy-4-(p-tolyldiazenyl)benzylidene)-2-(p-tolylamino)acetohydrazide (H2L) were prepared by direct method. The ligand and its complexes were isolated in solid state and characterized by analytical techniques such as elemental and thermal analyses, molar conductance, magnetic susceptibility measurements and spectroscopic techniques such as UV-Visible, IR, 1H-NMR and 13C-NMR. The spectral data indicated that the ligand acted as neutral/monobasic bidentate or monobasic/dibasic tridentate ligand bonded to the metal ions through the oxygen atom of ketonic or enolic carbonyl group, azomethine nitrogen atom and deprotonated/protonated phenolic oxygen atom forming either tetragonally distorted octahedral or octahedral. Antimicrobial activities of the ligand and its complexes were evaluated against Escherichia coli, Bacillus subtilis and Aspergillus niger by well diffusion method. The results of antifungal activity showed that the Fe(III) complex (10) exhibited higher antifungal against Aspergillus niger than the other complexes. However, the results of antibacterial activity revealed that Cu(II) complex (4) is the most active against Escherichia coli while the Cu(II) complex (5) and Fe(III) complex (10) exhibited higher antibacterial effect on Bacillus subtilis than the other complexes.