1994 Fiscal Year Final Research Report Summary
ANALYSIS OF MICRO REACTION-FIELD IN REVERSED MICELLES AS AN EXTRACTION・SEPARATION SYSTEM FOR METAL COMPLEXES
| Project/Area Number |
05453069
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
分離・精製・検出法
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| Research Institution | HIROSHIMA WOMEN' S UNIVERSITY (1994)
Hiroshima University (1993) |
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Principal Investigator |
IWAMOTO Etsuro HIROSHIMA WOMEN' S UNIV.HUMAN LIVE,PROFESSOR, 家政学部, 教授 (80033918)
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| Co-Investigator(Kenkyū-buntansha) |
KUMAMARU Takahiro HIROSHIMA UNIV.SCIENCE,PROFESSOR, 理学部, 教授 (50033816)
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| Project Period (FY) |
1993 – 1994
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| Keywords | PLANAR NI (II) COMPLEX / SOLVATOCROMISM / REVERSED MECELLE / HYDROGEN BONDING / COOPERATIVE INTERACTION / ION-SOLVENT INTERACTION / AOT / CETYLTRIMETHYLAMMONIUM CHLORIDE |
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| Research Abstract |
Surfactants such as sodium bis (2-ethyl-1-hexyl) sulfosuccinate (AOT) and cetyltrimethylammonium chloride (CTAC) aggregate in non-polar solvents and exhibit the remark able property of solubilizing large quantities of wate to form a spherical pool in the center of a mecelle (revered mecelles). The water pool fomed in reversed micelles has beem extensively used as a medium for chemical and biological reactions. The water properties in reversed micelles graduyally change as a function of the molar ratio (R=[H_2O]/[surfactant]) and also depend on the distance from the polar head.
The change in the polarization of water in AOT reversed micelles has benn investigated spectrtophotometrically using 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecanenickel (II) cation, [Ni(tmc)]^<2+>, as a probe of electron-pair acceptance. Although for R>10 the spectrum of the complex is very similar to that in bulk water, below R=10 the peaks of the five-coordinated complex shift to longer wavelengths and
… More
at R=1 the spectrum is very similar to that of the hydroxide ion-coordinated complex. This shows that a decrease in the R value obviously leads to a gradual increase in the polarization of water coordinated to [Ni(tmc)]^<2+> owing to the cooperative influence of the sulfo ion of AOT and [[Ni(tmc)]^<2+> through hydrogen bonding at the water/surfactant interface.
The counter chloride ion in the cationic CTAC reversed micelle is easily coordinated to [Ni(tmc)]^<2+> to fom the 100 % 5-coordinated complex [Ni(tmc)]^<2+> at a concentration of ca. 20 mol/1 for the chloride ion. On the contrary, the 100 % formation of 5-coordinated complex is impossible in the bulk aqueous solutions. In sodium chloride solution, for example, the coordinating ability of the chloride ion is decreased with increasing the concentration of sodium chloride because the cooperative interaction through hydrogen bonding among Na^+---OH-H--C1 decreases the electron density on the chloride ion. In the CTAC reversed micelle, such hydration does not occur because of low concentration of water.
A new method, based on the direct combination of solvent extraction with luminol chemilluminescence (CL) in a reversed micellar system of CTAC-water (buffered with sodium carbonate) -6.5 (v/v) chloroform-cyclohexane, is established for the detemination of gold in aqueous solutions. Separation of analyte from interferents by extraction with tri-n-octylphosphinenoxide in chloroform resulted in reduced or no interference. The method was applied to the determination of gold in industrial samples of silver-based alloy. Less
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[Publications] J.Nishimoto, A.Hironaka, E.Iwamoto and T.Kumamaru: "Coordination of water hydrogen-bonded to pyridine derivatives to the (1R,4S,8R,11S-1,4,8,11-tetramethyl-1,4,8,11-tetraaza-cyclotetradecanenickel (II) cation in nitrobenzene" Bull.Chem.Soc.Jpn. 66. 1669-1674 (1993)
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