• Bulletin of the Korean Chemical Society
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• v.16 no.11
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• pp.1015-1019
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• 1995

The electronic structures and properties of the neutral and multiply charged C60n ions (n=2+ to 6-) with spin states have been investigated by semi-empirical MNDO calculations. In the ground state, C601- has the lowest total energy and the highest binding energy. The neutral C60 ion is supposed to have a high ionization potential and a high electron affinity. The HOMO and LUMO positions are lower in the cationic C60 than in the anionic C60. The LUMO energy becomes increasingly positive from C601- to C606- and the HOMO energy becomes increasingly negative from C602+ to C60. The HOMO-LUMO gap of the neutral C60 ion is higher than that of the multiply charged C60 ions. From the HOMO-LUMO gap, it seems reasonable to expect that electrons of the multiply charged C60 ions will be more polarizable than those of the neutral C60 ion. The HOMO and LUMO energies increase as the negative charge increases.

• Analytical Science and Technology
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• v.20 no.1
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• pp.61-69
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• 2007

The geometrical parameters, total and relative energies, vibrational frequencies, the HOMO-LUMO energy gap, and reorganization energies for the neutral molecule, anion, and cation of $C_{16}H_{16}O_3$ have been determined using density functional method (DFT). The highest level of theory employed in this study is $B3LYP/6-311G^{**}$. Harmonic vibrational frequencies were determined at the $B3LYP/6-311G^{**}$ level of theory. All positive vibrational frequencies were obtained to confirm minimum structures. The HOMO-LUMO energy gap and reorganization energies were calculated to predict the charge transport property of liquid-crystal.

• Textile Coloration and Finishing
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• v.25 no.1
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• pp.7-12
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• 2013

The energy levels are very important to investigate properties of organic dye materials. These values of energy levels can be calculated and compared with absorption spectra, cyclic voltammetric measurement and computer simulative calculation. In this study, absorption and emission changes were observed by complexation between rhodamine 6G based dye and mercury. This is related to spirolactam ring system of rhodamine 6G based dye. According to structural change of this dye, HOMO and LUMO energy levels were investigated and determined by their values with different approaches.

• Textile Coloration and Finishing
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• v.25 no.1
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• pp.1-6
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• 2013

Nowdays, the computational simulation of molecular energy potentials and the empirical evidence using electrochemical reduction/oxidation values are very significant factors to predict of molecule's energy potentials. The prepared chemosensor herein consists of spirolactam ring system in the structure, providing intra-structural change with metal cation binding. In this study, rhodamine 6G-Naphthaldehyde chemosensor was determined and compared with HOMO/LUMO energy levels by computational calculation and cyclic voltammogram method.

• Journal of the Korean Chemical Society
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• v.68 no.4
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• pp.185-190
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• 2024

Recently, it was reported that the benzobisoxazole (BBO) molecule can be used for independent modulation of the HOMO and LUMO energy levels. In this study, we utilized this interesting property of BBO to quantitatively investigate the substituent effects according the substituents. We designed and proposed four BBO model systems (1BBO, 2BBO, 3BBO and 4BBO) by extending the π-conjugation lengths based on a BBO molecule. Two directions of substitution (x-axis and y-axis) and 15 various substituents were considered. From strong correlation between the LUMO energy levels of x-axis substitution and HOMO energy levels of y-axis substitution calculated from DFT method, it is found that the standardization of substitution effects can be established from BBO model systems. In addition, we demonstrated that the HOMO values of y-axis substituted 3BBO show the best performance to define the order of substituent effects. Our proposed way can be used to expect the substituent effect of any arbitrary substituents and develop the organic sensors and organic light emitting diodes.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.284-290
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• 2010

In this study, as one of the carbon dioxide ($CO_2$) adsorbents the aqueous potassium carbonate ($K_2CO_3$)/promoter mixtures were investigated. Equilibrium partial pressure ($P_{CO_2}^*$) and pressure change were measured by using VLE (Vapor-liquid equilibrium) equipment in the mixture solution at 60 and $80^{\circ}C$, respectively. Absorption capacity was estimated in the semi-batch absorption apparatus at 40, 60 and $80^{\circ}C$. We proposed to use homopiperazine (homoPZ), cyclic diamine compound as a promoter of $K_2CO_3$ solution, to prevent crystalline formation and increase absorption capacity of aqueous $K_2CO_3$ solution. The absorption capacity of $K_2CO_3$/homoPZ was compared with MEA, $K_2CO_3$ and $K_2CO_3$/piperazine (PZ). Based on the results, we found that the mixture solution containing homoPZ had lower equilibrium partial pressure than that of $K_2CO_3$ solution and the absorption rate was approximately 0.375-times faster at $60^{\circ}C$, 0.343-times faster at $80^{\circ}C$ than that of aqueous $K_2CO_3$ solution without homoPZ. $K_2CO_3$/homoPZ solution showed excellent CO2 loading capacity compared with MEA solution at $60^{\circ}C$.

• Rapid Communication in Photoscience
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• v.3 no.3
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• pp.59-60
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• 2014

The trans-$A_2B_2$ porphyrin and Ni-porphyrin derivatives were synthesized by Suzuki coupling of bromoporphyrin with arylborate as a key step. The band gaps of those complexes were measured from their absorption, emission and cyclic voltammetric data. All the LUMO energy level of porphyrin derivatives is lower than that of P3HT, and the HOMO energy level is evaluated higher than the HOMO of PCBM.

• Journal of the Korean Chemical Society
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• v.30 no.2
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• pp.172-180
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• 1986

The Hammett's substituent constants were analyzed for the substituted-benzoic acid, -benzene and -naphthalene by LCAO MO method. Hammett's ${\sigma}$-values have been theoretically proved to treat as the sum of independent contribution of inductive effect and resonance effect. That is, Is (static inductive effect) and Id (dynamic inductive effect) corresponding to inductive effect are chosen as net charge and approximate self atom polarizability indices respectively, and ${\Delta}E^{HOMO}$ which is the difference in HOMO energy level between substituted molecule and unsubstituted molecule as resonance effect. In conclusion, it has been found that the observed ${\sigma}$-values depend on the sum of Id, Is and ${\Delta}E^{HOMO}$.

• Textile Coloration and Finishing
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• v.25 no.2
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• pp.83-88
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• 2013

Rhodamine dyes have been studied in various scientific areas due to their excellent photophysical properties. In particular, these rhodamine dyes are one of the most famous fluorophores as signal unit in chemosensor study. This is related to spirolactam ring system in rhodamine dyes. When the spirolactam ring is closed, there is nonfluorescence and colorless. Whereas, ring-opening of the corresponding spirolactam induces strong fluorescence and color. These absorption and emission changes are related to structural changes as well as electron energy potential levels such as HOMO and LUMO values. In this study, two different structures of rhodamine 6G hydrazide depending on the spirolactam ring system were investigated using absorption measurement, electrochemical measurement and computational calculations.

• Bulletin of the Korean Chemical Society
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• v.28 no.2
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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.