• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.1202-1204
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• 2014

• Bulletin of the Korean Chemical Society
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• 제16권5호
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• pp.410-416
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• 1995

The proton transfer energies of gas phase glycine and alanine and those of hydrated glycine and alanine were calculated both with Hartree-Fock and $M{\Phi}ller-Plesset$ ab initio molecular orbital (MO) calculations with 6-31G** basis set. The transition states of the proton transfer of gas phase glycine was also investigated. For zwitterions, both for glycine and alanine, the water bound to -NH3+ site stabilize the complex more compared with the water bound to -CO2-. The proton transfer energy, ΔEpt, of glycine, alanine, mono-hydrated glycine, mono-hydrated alanine, di-hydrated glycine and di-hydrated alanine were obtained as 30.78 (MP2: 22.57), 31.43, 23.99 (MP2: 17.00), 24.98, 22.87, and 25.63 kcal/mol, respectively. The activation energy for proton transfer from neutral (Nt) glycine to zwitterion (Zw) glycine, Ea, was obtained as 16.13 kcal/mol and that for reverse process, Ear, was obtained as 0.85 kcal/mol. Since the transition state of the proton transfer of gas phase glycine locate near the glycine zwitterion on the potential energy surface and the shape of the potential well of the zwitterion is shallow, the zwitterion easily changed to neutral glycine through the proton transfer.

• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.798-804
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• 2014

We present calculations for diglycine - $(H_2O)_n$ (n = 0-3) to examine the effects of microsolvating water on the relative stability of the zwitterionic vs. canonical forms of the dipeptide. We calculate the structures, energies and Gibbs free energies of the conformers at wB97XD/6-311++G** and MP2/aug-cc-pvdz levels of theory level of theory. We predict that microsolvation by up to three water molecules does not give thermodynamic stability of the zwitterion relative to the canonical forms. Our calculations also suggest that zwitterionic diglycine - $(H_2O)_3$ is not stable kinetically in low temperature gas phase environment.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제4권3호
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• pp.195-200
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• 2000

The kinetics of the reaction between carbonyl sulfide and aqueous monoethanolamine were studied over a range of temperature (298-348 K) and amine concentrations using a wetted-sphere absorber. The key physicochemical properties used to interpret the data included the solubility and diffusivity of the COS in the aqueous amine solution. The experimental data were interpreted using a zwitterion mechanism, which produced an Arrhenius plot with third-order kinetic rate constants. The fit of these data was $K_3$=$1.32\times10(sup)10exp(\frac{-6136}{T}}$

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.97.2-97.2
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• 2012

This study examined the utility of two zwitterions, nitrile-functionalized zwitterions and a zwitterion without a nitrile group (MF-ZI), were used as additives along with 1 M $LiPF_6$ in ethylene carbonate (EC):diethylene carbonate (DEC) (3:7 V/V) (E-0) to form an electrolyte solution for use in lithium ion batteries comprising graphite and $LiCoO_2$ electrodes. The presence of NF-ZI (E-NF-ZI) in the electrolyte produced an ion conductivity comparable to that of E-0 and higher than that of an electrolyte containing MF-ZI (E-MF-ZI). Linear sweep voltammetry data revealed that the intensity of the E-NF-ZI reduction peak was lower than that of E-0. Furthermore, the successful formation of an SEI layer in the E-NF-ZI over graphite was confirmed by cyclic voltammetry data. These results were attributed to the adsorption of NF-ZI on the electrode surface, as verified by differential capacity measurements.

• 공업화학
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• 제3권4호
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• pp.579-587
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• 1992

올레핀의 오존화 반응에서 보여지는 통상의 반응경로가 pyridine의 도움으로 modification될 수 있는지 여부가 검토되었다. 먼저, trans-3-hexene의 오존 산화 반응이 aprotic non-participating solvent인 n-pentane과 dichloromethane을 사용하여 시험되었다. 덧붙여, 올레핀의 오존 산화 반응에서 pyridine의 역할과 반응기구를 검토하기 위하여, monomeric과 Polymeric ozonides의 염기성 촉매 분해반응이 시험되었다. 본 연구에서 반응 과정의 고찰뿐만 아니라 생성물의 정량, 정성 분석을 위하여 현대적인 분석 기기들이 사용되었다. 본 연구의 결과로서, Pyridine 무존재하 aprotic solvent에서 올레핀과 오존의 반응으로 주로 과산화물인 monomeric이나 polymeric ozonides가 생성되었으며, pyridine 존재하에서는 과산화물의 생성없이 propionaldehyde와 Criegee zwitterion의 자리옮김 생성물인 propionic acid가 주생성물이었다. 또한, tans-3-hexene의 오존 산화 반응에서 Pyridine의 촉매작용에 의하여 trans-3-hexene의 Criegee zwitterion의 propionic acid로 이성화되는 것으로 사료된다.

• Bulletin of the Korean Chemical Society
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• 제29권9호
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• pp.1705-1710
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• 2008

Imidazolium based zwitterions, 1,2-dimethylimidazolium-3-n-propanesulfonate (DMIm-3S) and 1-Butylimidazolium-3-n-butanesulphonate (BIm-4S), were synthesized, and utilized them as additive for Li ion cell comprising of graphite anode and $LiCoO_2$ cathode. The use of 10 wt% of DMIm-3S in 1 M $LiPF_6$, EC-EMCDMC (1:1:1 (v/v)) resulted in the increased high rate charge-discharge performance. The low temperature performance of the Li ion cells at about −20 ${^{\circ}C}$ was also enhanced by these zwitterion additives. The DMIm- 3S additive resulted in the better capacity retention by the Li-ion cells even after 120 cycles with 100% depth of discharge (DOD) at 1 C rate in room temperature. Surface morphology of both graphite and $LiCoO_2$ electrode before and after 300 cycles was studied by scanning electron microscopy. An analogous study was performed using liquid electrolyte without any additive.

• 한국광과학회:학술대회논문집
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• 한국광과학회 2005년도 제12회 학술대회 논문초록
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• pp.125-125
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• 2005

• 멤브레인
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• 제32권1호
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• pp.23-32
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• 2022

세균은 분리막, 식품 포장 필름 및 바이오 의료 기기와 같은 다양한 미생물 막의 표면 위에서 자란다. 미생물 막의 성장은 엑소폴리사카라이드의 복잡한 구조 형성과 밀접한 관련이 있다. 미생물 막이 항균제의 대량 수송의 어려움으로 성장하게 될 경우 항균효과는 급격하게 감소한다. 항균 활동을 활성화하기 위해서 막의 표면은 살균 특성이 있는 기능성 물질들로 변형, 코팅 또는 고정한다. 한 가지 아이디어는 막 표면에 양전하 이온을 도입하는 것이다. 양전하 이온인 4차 암모늄 그룹의 존재는 마그네슘이나 칼슘같이 세균 세포벽에 존재하는 2가 금속이온을 대체할 수 있다. 세포막 파괴의 효능은 표면환경에서 사용 가능한 작용제들의 이동성에 달려있다. 이 리뷰에서는 4차 암모늄 그룹, 헬라민(helamine), 쌍성이온(zwitterion)과 같이 여러 살생물제를 포함하고 있는 막들을 다룬다.

• Journal of Photoscience
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• 제1권1호
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• pp.15-23
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• 1994

The absorption and fluorescence spectral properties of piroxicam (PRX) in the hydrogenbonding solvents show the most sensitive dependence on the concentration ranging from 8 x 10$^{_5}$ to 2 x10$^{_5}$ M. These are attributed to both the solvent-mediated ground-state intermolecular proton transfer (GSIerPT) leading to formation of the ground state anion and the excited-state intmmolecular proton transfer (ESIraPT). The concentration dependences of the time-resolved emission kinetics at both room temperature and 77 K have also been investigated. It is shown that in the excited state, the ESIraPT of PRX is the dominant process to form a keto tautomer at the high concentration, whereas at the low concentration the excited-state conformational change of the anion is an additional process leading to formation of a zwitterion. The ESI~PT of PRX in the hydrogenbonding solvent is coupled with the ultrafast excited-state solvent reorganization.