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Cu(Ⅱ)이온과 Poly(vinyl alcohol)간에 생성되는 고분자-금속 착물의 열역학적 거동에 관한 연구
전은덕, 한정호, 조태섭 영남대학교 기초과학연구소 2000 基礎科學硏究 Vol.20 No.-
The dissociation constants for poly(vinyl alcohol) (PVA) at a constant ionic strength of μ=0.1(KCl) were measured by potentiometric titration at various temperatures. The formation constants for the Cu(II)-PVA complex at the same condition were also measured in this study. From the temperature dependence of those dissociation and formation constants, various thermodynamic parameters such as ΔG, ΔH, ΔS were determined. From the thermodynamic parameters, it was concluded that the dissociation of a proton from PVA is unfavorable with a negative entropy and positive enthalpy. In contrast, the complex formation was a spontaneous and exothermic process with favorable entropy.
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Pd(Ⅱ)이온과 Linear Poly(ethyleneimine)간에 생성되는 고분자-금속 착물의 구조와 성질에 관한 연구
한정호, 전은덕, 조태섭 영남대학교 기초과학연구소 2000 基礎科學硏究 Vol.20 No.-
Pd(II) metal ion has attracted interest of many researchers because of its potential applications and of its similarity and difference in chemical properties. In this study, complex formation of Pd(II) metal ion with polymeric amine ligand namely, linear poly(ethyleneimine)(LPEI), was investigated utilizing spectroscopic and potentiometric methods as well as elementary analysis. From UV/VIS spectroscopic study, complexation of LEPI to Pd(II) ion exhibit an absorption band at 347nm at the low mole ratio (below 2.0). This species can be understood either as the binuclear complex bridged by chloride ions or a complex of Pd(II) ion with three chloride ions and an amine group. At the high mixing ratio, absorption spectrum centered at 300nm was apparent, which is due to the complexation of LPEI to the Pd(II) ion. Mole ratio analysis for the LPEI-Pd(II) system revealed that complex formation was most stable at the LPEI ratio of 4.0 relative to metal ion. This result was confirmed by elementary analysis. From the potentiometric titration, successive and overall stability constants were measured and the results were analyzed by a modified Bjerrum method.
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Protonation State of Norfloxacin and Their Interaction with DNA
여정아,손관수,김종문,문형랑,전은덕,조태섭,Yeo, Jeong-Ah,Son, Gwan-Su,Kim, Jong-Moon,Moon, Hyung-Rang,Jun, Eun-Duk,Cho, Tae-Sub Korean Chemical Society 2000 대한화학회지 Vol.44 No.1
We investigated the self-association and protonation state of norfloxacin, a member of quinokme antibiotics, using electric absorption and potentiom,etric titration. Both nitrogen at the piperazine ring and carboxylic acid were protonated at a low pH (cationic norfloxacin), and deprotonated at a high pH (anionic norfloxacin). In the intermediate pH range, a neutral species was dominant with the possibility of forming a zwitter ion. We also observed that nortloxacin molecules can be sracked to form a dimer at an intermediate pH, The equilibrium constant of the norfloxacin-DNA complex formation, which was measured by Stem-Volmermethod, increases as the pH of the system is lowered. This observation indicates that it is the cationic nortloxacin that forms a complex with DNA among various norfloxacin species in aqueous solution. 여러 가지의 분광법과 전위차 적정법을 이용하여, 퀴놀론의 유도체인 norfloxacin의 자체 회합과 pH에 따른 형태에 대하여 연구하였다. norfloxacin의 작용기 중에서 피페라진 고리와 카르복실기의 두 질소원자는 낮은 pH 용액에서는 수소화(양이온 형태)되고, 높은 pH 용액에서는 두 수소가 모두 이탈하며(음이온 형태), 중간 pH 범위의 용액에서는 zwitter 이온이 두드러지게 형성되었다. 또한, 이 중간 pH용액에서는 norfloxacin 두 분자가 자체 회합을 이루었다. Stern-Volmer 측정법에 의하여 norfloxacin-DNA 결합체의 결합 상수를 조사하였는데, 용액의 pH가 낮을수록 그 결합 상수는 증가하였다. 이것은 용액 상태에서 DNA에 결합하는 norfloxacin의 분자종이 여러 분자종 중에서 그 형태가 양이온임을 나타내는 것이다.
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