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함승욱,조종인 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.5
The molecular structures of three conformers (cone [CONE], partial cone [PACO], and 1,2-alternate [12A]) of 1,2-bridged calix[4]aryl picrate 1 and their alkali-metal-ion complexes were optimized using a mPW1PW91/6-31G(d,p) (hybrid HF–DF) calculation method. The total electronic and relative binding energies and the gaps of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) frontier orbitals of the complexes of each conformer with sodium and potassium ions were analyzed. The HOMOs are mainly concentrated in the phenyl rings in calix skeleton as bonding orbitals, while the LUMOs are located in the picrate moieties as anti-bonding orbitals. The monotopic binding efficiency of the 1(CONE)·Na+(exo) complex (−98.0 kcal/mol) was the strongest among the six kinds of the Na+ complexes and much better than that of the 1(12A)·K+(exo) complex (−77.8 kcal/mol). The IR spectra of the conformers of 1 and their complexes with the alkali metal ions were calculated by mPW1PW91 and analyzed.
함승욱,조종인 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.1
The molecular structures of four conformers [cone (CONE), partial cone (PACO), 1,2-alternate (12A), and 1,3-alternate (13A)] of benzoylmethoxythiacalix[4]arene 1 and the corresponding alkali metal ion complexes were optimized by using a mPW1PW91/6-31G(d,p) (hybrid Hartree–Fock density functional) calculation method. The 13A conformer was the most stable among the various conformers of 1 because of less steric hindrance. The total electronic and Gibbs free energies, complexation energies, and the gap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) frontier orbitals of the complexes of 1 with the sodium and potassium ions were analyzed. Among the ditopic complexes, the 13A-type 1•2Na+ complex exhibited the strongest binding efficiency. The binding efficiency of the CONEtype 1•Na+ complex was much stronger than that of the 12A-type 1•Na+ complex. However, the 1•K+ complexes were relatively insensitive to the conformation of host 1. The calculated binding preference of the various conformers is consistent with the empirical solution data. The infrared spectra of the conformers of 1 and their exo complexes with the alkali metal ions were calculated by mPW1PW91 and analyzed.
Solid Phase Synthesis for Unnatural Oligomeric Libraries
송정환,유지상,함승욱 中央大學校 基礎科學硏究所 1999 基礎科學硏究所 論文集 Vol.13 No.-
Oligopeptides는 생체내에서 중요한 역할을 하지만 그 자체를 치료제로 사용하기에는 다음과 같은 문제점으로 인해 불가능하다. 생체내에서 이들은 여러 가지 단백질 분해 효소에 의하여 절단되고, 또한 생체막을 투과하기에는 친수성이 강하기 때문이다. 그래서, 조합화학자들에게 nonpeptide oligomeric library의 개발은 새로운 도전으로 다가오고 있다. 본 연구에서는 교대로 methylene sulfide로 변형된 peptide의 합성법을 제시하였다. 이 방법의 강점은 고체지지체에 붙어있는 생성물의 확인할 수 있다는 것과 격렬하지 않은 축합반응조건을 가지면서도 높은 수율을 보장한다는 것이다. 이 방법을 이용하여 얻게 될 최종 생성물은 교대로 변형된 골격구조와 D-form 입체 구조로 인하여 생물학적 안정성을 갖게 될 것이며, methylene sulfide가 갖는 소수성으로 생체막 투과성이 향상될 것으로 기대된다.
PTPase의 작용에 menadione이 미치는 활성 기작
함승욱,박희중,임두현 中央大學校 基礎科學硏究所 1995 基礎科學硏究所 論文集 Vol.9 No.-
Vitamin K₃(menadione) has been shown to exhibit a broad range of antitumor activity in human cells as well as a phosphatase cofactor. It also imposed lower level of toxicity than other cancer chemotherapeutic drugs of quinone structure. Juan and Wu have recently demonstrated that the action of menadione is dose-dependent and cell cycle-specific. In this study, we have examined the effect of menadione in the action of cdc25 PTPase which is important of the control of cell cycle progression by the signal transduction pathway. Our mechanistic analysis with the model reaction has led to a new interpretation of the role of menadione. We also investigated that thiolate addition of cdc25 PTPase to menadione leads to directly to irreversible inhibition by covalent modification.
Vitamin K 유도체를 이용한 산화 메카니즘의 연구
Lee, Kyo Chul,Ham, Seung Wook 中央大學校 基礎科學硏究所 1993 基礎科學硏究所 論文集 Vol.7 No.-
Vitamin K in its hydroquinone form, vitamin KH₂, is required as a cofactor a microsomal enzyme that converts N-terminal glutamate in proteins of the blotting clotting cascade to Υ-carboxyglutamate. In enzymic studies, it was suggested that the novel base strength enhancement by molecular oxygen was the key to understanding how vitamin K functions. In this work, the nonenzymic oxidation pathways of 2,3-dimethyl-and 2-methyl-1,4-naphthohydroquinone are examined. These data provide the chemical evidence suggesting the mechanism of action of vitamin K as well as the base amplication in the course of oxidation.
엄민식,함승욱,조종인 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.2
In this study, we describe the optimization of the three conformers (cone, partial cone, and 1,3-alternate) of 1,3-bridged p-tert-butylcalix[4]crown-7-ether ester (1) using the density functional theory (DFT) B3LYP/6-31G(d,p) method. 1(CONE) was calculated to be the most stable of the three conformations of 1. The structures, energies, and frontier orbitals (HOMO and LUMO) of the exo-complexes of 1(CONE) with alkylammonium ions were calculated using the DFT method. It was found that small alkylammonium cations exhibit a higher complexation efficiency with 1 than with larger alkylammonium ions. However, the branched alkylammonium ions exhibited stronger binding properties with 1 than the linear n-propyl and n-butyl ammonium ions. The DFT-calculated energies of 1 complexed with bulky alkylammonium ions exhibited stronger binding efficiencies than the calix[5]crown-6-ether (2). Hydrogen bonding and steric hindrance of the alkylammonium cations were found to be the primary factors governing the complexation efficiency of 1 with various cations. The DFT B3LYP/6-31G(d,p)-calculated IR spectra of the conformers of 1 and its cone-type exo-complexes with various alkylammonium ions were subsequently analyzed. The hydrogen-bonded NH and OH stretching vibrational frequencies were compared to the unrestricted vibrational frequencies in detail, and the unusually low NH stretching frequency (3054 cm−1) of the 1∙iso-Bu+ complex and the unusually low OH stretching frequency (3387 cm−1) of the 1∙n-Bu+ complex were determined to be caused by strong hydrogen bonding.