• Journal of the Korean Chemical Society
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• v.57 no.4
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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.

• Bulletin of the Korean Chemical Society
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• v.25 no.7
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• pp.1061-1064
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• 2004

Molecular visualization software has the common objective of manipulation and interpretation of data from numerical simulations. They visualize many complicated molecular structures with personal computer and workstation, to help analyze a large quantity of data produced by various computational methods. However, users are often discouraged from using these tools for visualization and analysis due to the difficult and complicated user interface. In this regard, we have developed an easy-to-use three-dimensional molecular visualization and analysis program named POSMOL. This has been developed on the Microsoft Windows platform for the easy and convenient user environment, as a compact program which reads outputs from various computational chemistry software without editing or changing data. The program animates vibration modes which are needed for locating minima and transition states in computational chemistry, draws two and three dimensional (2D and 3D) views of molecular orbitals (including their atomic orbital components and these partial sums) together with molecular systems, measures various geometrical parameters, and edits molecules and molecular structures.

• The Korean Journal of Pesticide Science
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• v.8 no.4
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• pp.265-271
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• 2004

Hydrolytic reactivities of N-phenylphthalimid herbicide flumioxazine (S) were disccused using molecular orbital (MO) theoretical method. It is revealed that below pH 5.0, the protonation $(SH^+)$ to carbonyl oxygens atom $(O_{21})$ of 1,2-dicarboximino group by general acid catalysis $(k_A)$ with hydronium ion $(H_3O^+)$ proceeds via charge controled reaction. Whereas, the specific base catalysis $(k_{OH})$ with hydroxide anion via orbital controled reaction occurs above pH 8.0. We may concluded that in the range of pH $5.0\sim8.0$, the hydrolysis proceeds through nucleophilic addition elimination $(Ad_{N-E})$ reaction, these two reactions occur competitively.

• Journal of the Korean Chemical Society
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• v.16 no.3
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• pp.119-134
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• 1972

Various MO methods with differing degrees of sophistication are shown to yield qualitatively consistent results for methyl isoalloxazins. However, with crude methods such as the HMO and ${\omega}$-technique, the choice of Coulomb and resonance integralsis critical, in contrast with simpler molecular systems. The empirical value of ${\omega}$=0.5 appears to be more reasonable than 1.4. Methyl groups in these flaving are best treated by the group orbital approximation. The pseudo-heteroatom approximation overestimates methyl hyperconfiguration with the Pariser-Parrpole SCR MO method. siglet ${\pi}{\rightarrow}{\pi}^*$ transition energies are calculated by the P-P-P method and agree reasonably with the experimental values. 2- and 4-Thioisoalloxazine analogs are also treated. Reactivity indices of the flavin molecule are presented, includeing superdelocalizability. frontier orbital and radical densities. Various aspects of the applications of these indices of the methyl groups on dipolemoments, inozation potentialsm elctron affinities, and spectra are decribed in detail.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1074-1078
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• 2004

열 중착 방법을 이용하여 copper(II)-phthalocyanine(CuPc) 박막을 glass 기판 위에 제작하였다. 박막은 열처리를 하지 않은 경우와 열처리 조건을 $150^{\circ}C$ 로 후열(annealing) 처리 하는 방식으로 하였으며 후열 처리한 경우 $150^{\circ}C$에서의 열처리 지속 시간을 각각 2시간, 3시간, 4시간으로 달리하였다. 제작된 박막의 전기전도도를 평가하기 위해 마이크로파의 근접장 효과를 이용한 근접장 현미경(near-field scanning microwave microscope)을 이용하여 비파괴적인 방식으로 CuPc 박막의 반사계수(reflection coefficient)를 측정하였다. CuPc 박막의 전기전도도 특성을 UV 흡수도를 통한 HOMO(highest occupied molecular orbital), LUMO(lowest unoccupied molecular orbital) 준위의 밴드갭의 shift 현상과 관련지어 설명하였다. 박막 표면 특성은 SEM(scanning microscope microscopy)을 통해 관측하였다. 열처리 지속 시간에 따른 CuPc 박막의 전기전도도 특성은 2시간으로 지속한 경우의 박막의 경우 가장 좋았으며 그 보다 더 오랜 시간 동안 열처리를 지속한 경우에는 전기 전도 특성이 오히려 나빠짐을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• v.3 no.3
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• pp.98-103
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• 1982

Extended Huckel calculations have been performed to obtain molecular orbital energies and the corresponding eigenvectors for $[M(III)O_3S_3]$ type complexes [M(111) = V(111), Cr(III), Mn(III), Fe(III) and Co(III)] adopting the valence basis set orbital $(nP_z)$ and the hybridized atomic orbital of ligands. The effects of the hybridized atomic orbital of ligands on the calculated dipole moments and 10 $D_q$ values are investigated. The calculated 10 $D_q$ values and dipole moments are close to the experimental values when the hybridized atomic orbital of ligands is used to obtain the eigenvector for $[M(III)O_3S_3]$ type complexes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.148-151
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• 2003

The spin density of ${\beta}-MnO_2$ structure was theoretically investigated by $DV-X_{\alpha}$ (the discrete variation $X{\alpha}$) method, which is a sort of the first principle molecular orbital method using Hatre-Fock-Slater approximation. The used cluster model was $[Mn_{14}O_{56}]^{-52}$. The ${\beta}-MnO_2$ is a paramagnetic oxide semiconductor material having the energy band gap of 0.18 eV and an 3 loan-pair electrons in the 3d orbital of an cation. This material exhibits spin-only magnetism and has the magnetic ordering temperature of 94 K. Below this temperature its magnetism appears as antiferromagnetism. The calculations of electronic state showed that if the initial spin condition of input parameters changed, the magnetic state changed from paramagnetic to antiferromagnetic. When d orbital of all Mn atoms in cluster had same initial spin state as only up spin, paramagnetic spin density distribution appeared by the calculation. On the other way, d orbital had alternately changed spin state along special direction the resulted spin distribution showed antiferromagnetism.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2358-2368
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• 2011

Density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations, employing the B3LYP method and the LANL2DZ, 6-31G$^*$(LANL2DZ for Tc), 6-31G$^*$(cc-pVDZ-pp for Tc) and DGDZVP basis sets, have been performed to investigate the electronic structures and absorption spectra of the technetium-99m-labeled methylenediphosphonate ($^{99m}Tc$-MDP) complex of the simplest diphosphonate ligand. The bonding situations and natural bond orbital compositions were studied by the Mulliken population analysis (MPA) and natural bond orbital (NBO) analysis. The results indicate that the ${\sigma}$ and ${\pi}$ contributions to the Tc-O bonds are strongly polarized towards the oxygen atoms and the ionic contribution to the Tc-O bonding is larger than the covalent contribution. The electronic transitions investigated by TDDFT calculations and molecular orbital analyses show that the origin of all absorption bands is ascribed to the ligand-to-metal charge transfer (LMCT) character. The solvent effect on the electronic structures and absorption spectra has also been studied by performing DFT and TDDFT calculations at the B3LYP/6-31G$^*$(cc-pVDZ-pp for Tc) level with the integral equation formalism polarized continuum model (IEFPCM) in different media. It is found that the absorption spectra display blue shift in different extents with the increase of solvent polarity.

• Journal of Integrative Natural Science
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• v.15 no.4
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• pp.179-186
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• 2022

The c-Jun N-terminal kinase (JNK3) play major role in neurodegenerative diseases like Alzheimer's disease, Parkinson's disease, cerebral ischemia and other Central Nervous System disorders. Since JNK3 is primarily stated in the brain and stimulated by stress-stimuli, this situation is conceivable that inhibiting JNK3 could be a possible treatment for the mechanisms underlying neurodegenerative diseases. In this study drugs from Zinc15 database were screened to identify the JNK3 inhibitors by Molecular docking and Density functional theory approach. Molecular docking was done by Autodock vina and the ligands were selected based on the binding affinity. Our results identified top ten novel ligands as potential inhibitors against JNK3. Molecular docking revealed that Venetoclax, Fosaprepitant and Avapritinib exhibited better binding affinity and interacting with proposed binding site residues of JNK3. Density functional theory was used to compute the values for energy gap, lowest unoccupied molecular orbital (LUMO), and highest occupied molecular orbital (HOMO). The results of Density functional theory study showed that Venetoclax, Fosaprepitant and Avapritinib serves as a lead compound for the development of JNK3 small molecule inhibitors.

• Journal of the Korean Chemical Society
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• v.50 no.4
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• pp.281-290
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• 2006

The electronic structure and properties of the 1H-indene and mono-sila-1H-indene series have been investigated using basis set of 6-31G(d, p) and hybrid density functional theory. Basic measures of aromatic character derived from structure, molecular orbitals, a variety of magnetic criteria (magnetic isotropic and anisotropic susceptibilities) are considered. Energetic criteria suggest that In(Si7) enjoy conspicuous stabilization. However, by magnetic susceptibility isotropic this system are among the least aromatic of the family: Within their isomer series, In(Si4) is the most aromatic using this criteria. Natural bond orbital (NBO) analysis method was performed for the investigation of the relative stability and the nature of the 8-9 bonds in 1H-indene and mono-sila-1H-indene compounds. The results explained that how the p character of natural atomic hybrid orbital on X8 and X9 (central bond) is increased by the substitution of the C8 and C9 by Si. Actually, the results suggested that in these compounds, the X8-X9 bond lengths are closely controlled by the p character of these hybrid orbitals and also by the nature of C-Si bonds. The magnitude of the molecular stabilization energy associated to delocalization from X8-X9 and to * X8-X9 bond orbital were also quantitatively determined. Molecular orbital (MO) analysis further reveal that all structure has three delocalized MOs and two delocalized MOs and therefore exhibit the aromaticity.