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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 37, Number 5
JKCSEZ 37(5)
October 20, 1993 

 
Title
Studies on the Spectrophotometric Determination, Electrochemical Behavior of Heavy Lanthanide ions in Nonaqueous System and Heavy Chelates Complexes with Bidendate Ligands (Ⅱ) Electrochemical Behavior of Heavy Lanthanide Ions in Acetonitrile

무거운 란탄이온의 분광학적 정량, 비수용액에서의 전기화학적 거동 및 중금속이온과 두자리 리간드 착물에 관한 연구 (제 2 보)
Author
Sam-Woo Kang, Chong-Min Pak, Il-Kwang Kim, Lee-Mi Do, Jong-Min Lee

강삼우, 박종민, 김일광, 도이미, 이종민
Keywords
Abstract
무거운 란탄족 금속이온의 전기화학적 거동을 acetonitrile 용액에서 직류 및 펄스차이 폴라로그래피 및 순환전압전류법으로 연구하였다. Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+ 및 Lu3+ 은 0.1M TEAP 지지전해질에서 3전자 전비가역반응이었으며, Yb3+는 단계적인 환원반응으로 나타났다. 순환전압전류법에서 Yb3+의 첫번째 환원반응은(Yb3+ + e- → Yb2+) 유사가역적 거동을 나타냈으며, 두번째 환원반응은 전비가역적 거동을 나타냈다. 환원봉우리전류는 짙은 농도범위에서 주사속도가 저속일수록 흡착특성을 나타냈다. 물-acetonitrile 혼합용매에서 무거운 란탄이온은 물의 부피비가 증가할수록 음전위 이동하였으며 환원전류는 감소하였다. 이같은 현상은 acetonitrile보다 주개수가 큰 물의 용매화 능력이 증가하는 것으로 생각된다. 또한 Yb(Ⅲ)의 첫번째 환원과는 몰 부피비가 증가함에 따라 유사가역적 거동에서 벗어나는 현상이었다.

Voltammetric behavior of heavy lanthanide ions has been investigated by the DC, DPP and CV in acetonitrile solution. The reduction of Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+ and Lu3+ proceed by three-electron change to the metallic state with totally irreversibility in 0.1M tetraethylammonium perchlorate. However, the reduction of Yb(Ⅲ) proceeds in two steps (Yb3+ + e- → Yb2+ and Yb2+ + 2e- → Yb0). The first reduction of Yb(Ⅲ) showed quasi reversible behavior, but the second reduction was irreversible in cyclic voltammetry. The cathodic peak current showed adsorptive properties in high concentration with lower sweep rate. The electroreduction of heavy lanthanides in water-acetonitrile mixture has been studied. In water-acetonitrile mixture, the negative shift of the peak potential and the decrease peak current were observed increasing water concentration. Also the Yb(Ⅲ) reduction to Yb(Ⅲ) has been deviated from quasi-reversible character with increase water amount. These results drive from the high solvation abilities of water which has high donor number.

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483 - 490
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