• Bulletin of the Korean Chemical Society
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• 제20권2호
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• pp.147-149
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• 1999

The electronic structures of α- and β-gold selenides are studied. α- and β-AuSe are known as mixed valence compounds having linear (AuSe2, Au+) and square-planar (AuSe4, Au3+) units in their structure simultaneously. Our EHTB calculations, however, show that the oxidation states of Au in α- and β-AuSe are both close to +1. This is because the frontier orbitals are largely made up of Se p-orbitals and Au d-orbitals that lie well below the Fermi level. Our results are consistent with the recent X-ray absorption spectroscopy study on AuSe which show that all Au in the compound exhibit a monovalent state independent of their chemical environments.

• 제어로봇시스템학회논문지
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• 제14권4호
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• pp.365-368
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• 2008

Feasibility test for radical reactions in organic light emitting diode(OLED) has been applied on OLED consisting of hole transport layer(HTL) and electron transport layer(ETL). Organic molecules such as 4,4',-Bis[N-(1-naphthyl)-N-phenylamino] biphenyl(NPD) and 4,4',4"-tris(3-methylphenylphenylamino)triphenylamine(m-MTDATA) are chosen for hole transport layer(HTL) and Bathocuproine(BCP) for electron transport layer(ETL) in this study. Informations on energy and shape of frontier orbitals and data on radical reactions of simple aromatics from semiconductor($TiO_2$) photocatalysis have provided basis for determining feasibility for radical reactions in OLED. The outcome of our feasibility test would be useful in designing optimum molecule for organic layer with a view to extending the lifetime of OLED.

• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2403-2407
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• 2013

The hybrid density-functional (B3LYP/6-31G(d,p)) method was used to analyze the substitution effect on the $C_{20}H_{20}$ cage based on calculation of the frontier orbitals of fifteen $C_{20}H_{17}(OH)_3$ derivatives. All substitution products were geometrically optimized without constraints and confirmed by frequency analysis. The results suggest that the cis-1 cis-1 cis-2 regioisomer is the most stable isomer, which implies that hydrogen bonding exerts a stronger effect on the relative energies of the trihydroxide than long-range interactions. Thus, this supports the experimental result in which the bisvicinal tetrol was of particular preparative-synthetic interest. While the LUMO of each of the $C_{20}H_{17}(OH)_3$ regioisomers was equivalently delocalized over the void within the cage, the HOMO was limitedly delocalized on substituents and carbons in close proximity to the substituents. The characteristics of the HOMO of each of the regioisomers vary based on the substitution sites. This indicates that the 15 regioisomers of each $C_{20}H_{20}$ trisubstituted derivative might undergo an entirely different set of characteristic chemical reactions with electrophilic reagents. The results further suggest that the penta-substituted OH groups on the surface of the fullerene cage are more likely to be localized on a pentagon than to be homogeneously delocalized.

• Bulletin of the Korean Chemical Society
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• 제20권4호
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• pp.441-444
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• 1999

The alkyl Grignard addition reaction on 1-benzyltetrazolylimine proceeds to give N-alkylated products (azophilic addition) and, in contrast, the same reaction on 2-benzyltetrazolylimine produced predominantly C-alkylated products (carbophilic addition). In this report we described theoretical explanations for this experimental finding on the basis of the frontier molecular orbitals and the electrostatic nature of the reactants and the reaction intermediates.

• 약학회지
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• 제33권2호
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• pp.87-100
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• 1989

Salicylic acids as anti-inflammatory agents were analyzed by ab initio, quantum chemical methods to study the possible modes of binding to the receptor. As the result of multiple regression analysis of reactivity indices and interpretation of normalized frontier orbital charges of drugs, potency seems to be related to energy of HOMO and LUMO at the 5 position of benzene ring, and in the 5-phenyl substituted case, the para position of substituting ring is important. The binding occurs first at the positive site of its receptor. The charge density exhibited by the frontier orbitals suggests that charge moves from receptor site to carboxyl group. The electrostatic orientation effect makes an important contribution to the binding of the active molecules to their receptors. Also the electrostatic potential model may be able to rationalize the source of activity or inactivity of the drugs under investigation.

• Bulletin of the Korean Chemical Society
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• 제14권1호
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• pp.101-107
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• 1993

Ab initio calculations are carried out at the 6-311G$^{**}$ level for the $C_{2v}$ interactions of Be and Li atoms with acetylene molecule. The main contribution to the deep minima on the $^3B_2\;BeC_2H_2\;and\;^2B_2 LiC_2H_2$ potential energy curves is the b_2\;(2p(3b_2)-l{\pi}_g^*(4b_2))$ interaction, the $a_1\;(2s(6a_1)-I{\pi}_u(5a_1))$ interaction playing a relatively minor role. The exo deflection of the C-H bonds is basically favored, as in the $b_2$ interaction, due to steric crowding between the metal and H atoms, but the strong in-phase orbital interaction, or mixing, of the $a_1$ symmetry hydrogen orbital with the $5a'_1,\;6a'_1,\;and\;7a'_1$ orbitals can cause a small endo deflection in the repulsive complexes. The Be complex is more stable than the Li complex due to the double occupancy of the 2s orbital in Be. The stability and structure of the $MC_2H_2$ complexes are in general determined by the occupancy of the singly occupied frontier orbitals.

• 대한화학회지
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• 제28권5호
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• pp.284-292
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• 1984

치환체-E-arene-diazocyanides와 nitrosobenzenes의 (4+2) 고리첨가 반응의 배향성에 대한 치환기 및 산 촉매효과와 반응성을 예측하기 위하여 Diels-Alder 반응의 열 또는 촉매반응에 대하여 Frontier orbital theory (FMO)이론을 적용해서 CNDO/2 방법과 EHT-SPD 방법으로 고찰하였다. (1) 위 반응은 Hammett 식의 rho(${\rho}$)값이 양이므로 normal electron demand 반응형태를 가지며 4-FMO 및 Anh 방법이 실험적인 주 배향체와 일치함을 알았다. (2)전자끄는 기로 치환되면 dienophile의 HOMO, LUMO 궤도함수에너지가 낮아지고 반응성이 커지는 것을 알았다. (3)Lewis 산은 dienophile과 착물을 형성하고 dienophile의 LUMO계수를 정 반대로 분극시켜 주므로 주 배향제는 B형으로 예측된다. (4) diene HOMO-dienophile LUMO 상호작용의 안정화 에너지 (${\Delta}$E)와 Hammett식의 시그마 (${\sigma}$)값과의 그라프에서는 좋은 직선성을 보여 주었다.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2005년도 수소연료전지공동심포지움 2005논문집
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• pp.329-334
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• 2005

In order to find out rational design and synthetic strategies toward efficient hydrogen storage materials, we performed quantum mechanical calculations on a series of the Metal-Organic Frameworks (MOFs) containing functionalized organic linkers. Based on the shape of frontier orbitals and the electrostatic potential map of various MOFs from density functional theory calculations, it was found that the delocalization of electron and asymmetric polarization of the organic linker play an important role in the hydrogen storage capacity of Metal-Organic Frameworks. The prediction of the modeling study could be supported by the hydrogen adsorption experiments using MOF-5 and amine substituted MOF-5, which showed more enhanced hydrogen storage capacity of amine substituted MOF-5 compared with that of MOF-5.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2369-2376
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• 2007

N2O has been found from experimental and theoretical considerations to bind on-top to the Pd(110) surface in a tilted end-on fashion via its terminal N atom. We use a frontier orbital description of the bonding interactions in the Pd-N2O system to obtain molecular insight into the catalytic mechanism of the activation of N2O by the Pd(110) surface giving rise to the formation of N2 and O on the surface. For the tilted end-on N2O binding mode, the LUMO 3π of N2O has good overlap with the Pd dσ and dπ orbitals which can serve as the electron donors. The donor-acceptor orbital overlap is favorable for electron transfer from Pd to N2O and is expected to dominate the surface reaction pathway of N2O decomposition.

• 대한화학회지
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• 제57권4호
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• pp.461-471
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• 2013

Optimized geometrical structure, atomic charges, molecular electrostatic potential, nonlinear optical (NLO) effects and thermodynamic properties of the title compound N-(2,5-methylphenyl)salicylaldimine (I) have been investigated by using ab initio quantum chemical computational studies. Calculated results showed that the enol form of (I) is more stable than keto form. The solvent effect was investigated for obtained molecular energies, hardneses and the atomic charge distributions of (I). Natural bond orbital and frontier molecular orbital analysis of the title compound were also performed. The total molecular dipole moment (${\mu}$), linear polarizability (${\alpha}$), and first-order hyperpolarizability (${\beta}$) were calculated by B3LYP method with 6-31G(d), 6-31+G(d,p), 6-31++G(d,p), 6-311+G(d) and 6-311++G(d,p) basis sets to investigate the NLO properties of the compound (I). The standard thermodynamic functions were obtained for the title compound with the temperature ranging from 200 to 450 K.