• Carbon letters
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• 제8권4호
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• pp.292-298
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• 2007

In order to investigate functional groups on the surface of Multi-walled Carbon Nanotubes (MWCNTs) induced by oxyfluorination, XPS (X-ray photoelectron spectroscopy) analysis was carried out. All core level spectra of MWCNTs were deconvoluted to several Pseudo-Voigt functions (sum of Gaussian-Lorentzian functions). Both O1s and F1s binding energy of oxyfluorinated MWCNTs shifted high value as increment of fluorine mixing ratio. The carbon-fluorine covalent bonding concentration increased as increment of fluorine mixing ratio. The shape and intensity of OF10-MWCNTs are similar with those of as-received MWCNTs. However, the intensity and binding energies of main peak position of OF20-MWCNTs and OF30-MWCNTs were dramatically increased by oxyfluorination.

• 한국전기전자재료학회논문지
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• 제27권3호
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• pp.146-150
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• 2014

As a method of simple patterning of transparent conductive oxide (TCO) films deposited on flexible substrates, laser direct etching was carried out on TCO films sputtered on polycarbonate (PC) substrates. As a result of different binding energies in TCO films, indium tin oxide (ITO) and indium gallium zinc oxide (IGZO) were more easily etched than zinc oxide with different $Nd:YVO_4$ laser beam conditions.

• Bulletin of the Korean Chemical Society
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• 제28권2호
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• pp.241-245
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• 2007

The electronic structures of the new organic conducting salts, the β'- and β''-phases of (BEDT-TTF)2[(IBr2)0.2(BrICl)0.1(ICl2)0.7], were examined by calculating their electronic band structures, Fermi surfaces and HOMO-HOMO interaction energies using the extended Huckel tight binding method. On the basis of these calculations, we probed why the β'-phase is semiconducting while the β ''-phase is metallic.

• Bulletin of the Korean Chemical Society
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• 제22권11호
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• pp.1248-1254
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• 2001

The conformations and energies of p-tert-butylcalix[4]crown-6-ether (1) and its alkyl ammonium complexes have been calculated by ab initio HF/6-31G quantum mechanics method. The cone conformation was found to be most stable for free host 1. We hav e determined the binding site of these host-guest complexes focusing on the crown-6-ether or p-tert-butylcalix[4]arene pocket of the cone conformation of host molecule 1. The primary binding site of host 1 for the recognition of alkyl ammonium guests was confirmed to be the central part of the crown moiety of cone conformation. The complexation energy calculations revealed that the ammonium cation without alkyl group showed the highest complexation efficiency when combined with host 1, that is in satisfactory agreement with the experimental results.

• EDISON SW 활용 경진대회 논문집
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• 제4회(2015년)
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• pp.304-307
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• 2015

Carbon nanotubes (CNTs) have been widely accepted and used as the enhancer for polymer nano-composites due to their remarkable mechanical properties. Understandably, the CNT fiber-polymer matrix interface plays a major role in determining the properties of the CNT-polymer nano-composites. Here, using the LCAODFT Lab tool available on the EDISON Nano-Physics site, we performed first-principles density-functional theory calculations to determine the atomic configurations and binding energies of the CNTs in contact with polymers. For the polymer matrixes, we chose poly(acrylonitrile) (PAN), which is one of the most well-known polymer matrixes for the carbon nanofiber nanocomposites. Different chiralities and diameters of pristine CNTs were considered, and several PAN-CNT configurations were prepared based on the atomistic positions and directions of cyano group in PAN. The most favorable configuration of PAN was obtained when the PAN bound parallel to the surface of CNT. Our finding indicates the binding configurations are determined by the direction of the cyano group dominantly rather than the atomistic position of PAN, or the symmetry of CNTs. The result of increasing the length of CNT diameter suggests that PAN is inclinable to align evenly on the surface of relatively large size of CNT with the configuration parallel to the surface. These results obtained in this study will provide the starting point for the design of improved PAN-CNT composites for the next-generation ultra-strong and ultra-light carbon nanofibers.

• Bulletin of the Korean Chemical Society
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• 제28권8호
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• pp.1363-1370
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• 2007

The geometrical structures of pyridazin-3-one derivatives (4,5-dihalopyridazin-3-one and 4-halo-5- alkoxypyridazin-3-one) with various functional and substituent groups were fully optimized using the ab initio Hartree-Fock (HF) and second order Moller-Plesset perturbation (MP2) methods. At the N2-, C4-, and C5- positions on the pyridazin-3-one rings, the structural and electronic features pertaining to the variations of the functional and substituent groups were analyzed, respectively. The trends in the variation of the bond lengths, atomic charges, and energetics (relative energy, binding energy) of the derivatives induced by changing the electron donating functional groups (X1 = OMe, OEt) to electron withdrawing groups (X1 = Cl, NO2) were examined. The variations of the bond lengths, atomic charges, and binding energies with the electron withdrawing strength of the substituent groups (Y = Me → F) were also investigated.

• Molecules and Cells
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• 제28권5호
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• pp.447-453
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• 2009

The quorum sensing (QS) inhibitors that antagonize TraR, a receptor protein for N-3-oxo-octanoyl-L-homoserine lactones (3-oxo-C8-HSL), a QS signal of Agrobacterium tumefaciens were developed. The structural analogues of 3-oxo-C8-HSL were designed by in silico molecular modeling using SYBYL packages, and synthesized by the solid phase organic synthesis (SPOS) method, where the carboxamide bond of 3-oxo-C8-HSL was replaced with a nicotinamide or a sulfonamide bond to make derivatives of N-nicotinyl-L-homoserine lactones or N-sulfonyl-L-homoserine lactones. The in vivo inhibitory activities of these compounds against QS signaling were assayed using reporter systems and compared with the estimated binding energies from the modeling study. This comparison showed fairly good correlation, suggesting that the in silico interpretation of ligand-receptor structures can be a valuable tool for the pre-design of better competitive inhibitors. In addition, these inhibitors also showed anti-biofilm activities against Pseudomonas aeruginosa.

• 대한화학회지
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• 제59권5호
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• pp.387-396
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• 2015

HOOO-(H₂O)_n (n=1~5) 클러스터에 대해서 다양한 기저집합과 밀도 범함수 이론(DFT) 및 순 이론(ab initio) 방법을 사용하여 가능한 여러 구조를 최적화하고 결합에너지와 조화진동수를 계산하였다. HOOO 단량체의 경우에는 CCSD(T) 이론 수준에서 trans 구조가 cis 구조보다 열역학적으로 더 안정한 것으로 계산되었다. HOOO-(H₂O)_n 클러스터에 대해서는 B3LYP/aug-cc-pVTZ와 CAM-B3LYP/aug-cc-pVTZ 이론 수준에서 분자 구조를 최적화하고 열역학적으로 가장 안정한 분자구조를 예측하였다. HOOO-H₂O 클러스터의 결합에너지는 MP2//CAM-B3LYP 한 점 에너지 계산에서 영점 진동에너지(ZPVE)와 바탕 집합 중첩에러(BSSE)까지 모두 보정한 후 6.05 kcal/mol로 계산되었으며, n=2-5의 경우에는 물 분자의 수가 증가 할수록 물분자 1개 당 평균 결합에너지는 증가하여 약 7.2 kcal/mol의 값으로 수렴하였다.

• 대한화학회지
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• 제59권2호
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• pp.117-124
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• 2015

Hydrogen polyoxide, $H_2O_n-H_2O_m$(n=1-4, m=1-4) 이중합체(dimer)의 분자 구조 변화에 따른 수소결합(H-bonding) 효과를 순 이론적(ab initio) 방법과 밀도 범함수 이론(DFT)으로 계산하였다. 분자 구조는 B3LYP, CAM-B3LYP, MP2의 양자역학적 방법들을 사용하여 최적화하였으며, 진동주파수를 계산하여 최저에너지(true local minimum) 구조인 것을 확인하였다. 보다 정확한 수소결합 에너지(${\Delta}E$) 계산을 위하여 CCSD(T) 이론수준에서 한 점(single-point) 에너지 계산을 하였으며, 영점 진동에너지(ZPVE) 보정과 바탕집합 중첩에러(BSSE) 보정을 하였다. CCSD(T)/cc-pVTZ 이론 수준에서 $H_2O_4-H_2O_3$이 8.18 kcal/mol로 가장 강한 결합을 나타내었으며, 물 이중합체($H_2O-H_2O$)는 3.00 kcal/mol로 가장 약한 결합에너지를 나타내었다.

• Bulletin of the Korean Chemical Society
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• 제33권10호
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• pp.3285-3292
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• 2012

The interaction of thiazole drug with (6,0) zigzag single-walled boron nitride nanotube of finite length in gas and solvent phases was studied by means of density functional theory (DFT) calculations. In both phases, the binding energy is negative and presenting characterizes an exothermic process. Also, the binding energy in solvent phase is more than that the gas phase. Binding energy corresponding to adsorption of thiazole on the BNNT model in the gas and solvent phases was calculated to be -0.34 and -0.56 eV, and about 0.04 and 0.06 electrons is transferred from the thiazole to the nanotube in the phases. The significantly changes in binding energies and energy gap values by the thiazole adsorption, shows the high sensitivity of the electronic properties of BNNT towards the adsorption of the thiazole molecule. Frontier molecular orbital theory (FMO) and structural analyses show that the low energy level of LUMO, electron density, and length of the surrounding bonds of adsorbing atoms help to the thiazole adsorption on the nanotube. Decrease in global hardness, energy gap and ionization potential is due to the adsorption of the thiazole, and consequently, in the both phases, stability of the thiazole-attached (6,0) BNNT model is decreased and its reactivity increased. Presence of polar solvent increases the electron donor of the thiazole and the electrophilicity of the complex. This study may provide new insight to the development of functionalized boron nitride nanotubes as drug delivery systems for virtual applications.