2001 Fiscal Year Final Research Report Summary
Development of analytical methods based on specificity of interfaces and their structural and kinetic stulies
| Project/Area Number |
11304054
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
分離・精製・検出法
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
TERAMAE Norio Tohoku University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (70114569)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIZAWA Seiichi Tohoku University, Graduate School of Science, Assistant, 大学院・理学研究科, 助手 (40281969)
UCHIDA Tatsuya Tohoku University, Graduate School of Science, Assistant, 大学院・理学研究科, 助手 (30261548)
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| Project Period (FY) |
1999 – 2001
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| Keywords | Interface / Molecular recognition / Artificial receptors / Fluorescence / Second Harmonic Generation / Time-resolved measurements / nano-particles / meso-porous materials |
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| Research Abstract |
As to analytical reaction fields, solid-liquid interface, liquid-liquid interface, meso-porous channels of silcate material, gold and semiconductor nano particles are investigated to obtain highly selective and/or specific recognition of molecules and ions using hydrogen bonding artificail receptors. Gold nano-particles modified with thiolated compounds which have molecule or ion recognition sites. The chemically modified gold particles show dramatic color change from red to blue by addition of target molecules or ions in water. Nano-sized semiconductor particles were also modified by thiolated carboxylic compounds, and sensing lead ions was succesfully attained based on photo-induced electron transfer mechanism. Highly selective sensing of very hydrophilic anions was succeeded using liquid-liquid interfaces as recognition fields. Ion-pair complexation behaviors of a thiourea-based bifunctional receptor with alkali metal ions and anions are examined at the 1,2-dichloroethane-water inte
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rface by dynamic interfacial tensiometry. A decrease in the interfacial tension, caused by the interfacial adsorption of the receptor in the organic phase, is promoted when alkali metal salts are added in the aqueous phase. The adsorption constants of the receptor depend on alkali metal salts. The results indicate that hydrogen bonding formation between the receptor and anions is actually effective at the liquid-liquid interface despite the significant interference from anion hydration. A more important property of the receptor at the liquid-liquid interface is the preferential binding of dihydrogen phosephate over chloride. This kind of selectivity has merely observed in ionophore-based chemical sensors such as ion-selective electrodes, where the selectivity is governed predominantly by the order of the free energy of hydration of the analyte anions. Anion transfer from aqueous phase to water phase was also investigated by liquid droplet polarography, A hydrogen bond-forming bis-thiourea was able to effectively facilitate the transfer of various hydrophilic anions across the nitrobenzene-water interface, suggesting possible use of the receptor for multianalyte detection with an amperometric sensing mode. In addition, chloride transfer across the nitrobenzene-water interface facilitated by the ionophore was studied, and a well-defined wave could be observed, indicating that the chloride transfer across the interface was facilitated by the ionophore via formation of hydrogen bonds. The analysis of ion transfer polarograms showed that the chloride transfer was assisted by 1 : 1 complexation between 2 and chloride, and the transfer process was reversible and controlled by diffusion of the ionophore from the bulk organic phase to the interface. Despite its simple binding mode based on two point interactions, mono-thiourea showed a strong ability to facilitate chloride transfer compared with a ionophore in which four hydrogen bonds were involved in the chloride binding. Dyanamical studies were also carried out by laser spectroscopies. Less
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