2003 Fiscal Year Final Research Report Summary
Development of Anion Receptors Utilizing Hydrophobic Space Formed by Dendrimer Structures
| Project/Area Number |
14550825
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Synthetic chemistry
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| Research Institution | Osaka University |
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Principal Investigator |
TOBE Yoshito Osaka University, Graduate School of Engineering Science, Professor, 基礎工学研究科, 教授 (60127264)
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| Project Period (FY) |
2002 – 2003
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| Keywords | Dendrimers / Receptors / Anions / Ion-selective Electrodes / Hydrogen Bonds / Hydrophobic Interactions |
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| Research Abstract |
There have been strong demands from the fields of environmental and clinical analyses to analyze conveniently trace anions dissolved in aqueous media. In this respect, we designed molecules having hydrophobic space formed by the benzyl type dendrimer structure, which may capable of binding anions at the water-membrane interface, producing sufficient electrical response as ion-selective electrodes. From the same points of view, preparation of highly dense dendrimers of phenylacetylene type, which may be used as fluorescence sensors for anions, was also carried out.
The benzylic dentrimers of 1st to 4th generations having a thiourea binding site wee prepared. By the NMR dilution experiments, it was clarified that their aggregation in nonpolar solvents was not significant enough to disturb binding with anions. On the basis of the titration experiments with dihydrogenphosphate anion using UV-vis spectroscopy, the binding constants in chloroform were determined to be in the order of 10^3 M^<-1> and the values were not much dependent on the generation. Though none of the dentrimers responded toward dihydrogenphosphate anion as ion-selective electrodes using a PVC membrane containing them, they exhibited sufficient response toward hydrogensulfate anion, which is also known to be strongly hydrated.
Dense phenylacetylene type dendrimers of 2nd generation was successfully prepared by using the protocol developed in our laboratory. The fluorescence efficiency of the dendrimer was slightly reduced compared with the 1st generation hexaethynylbenzene. Since the preparation of a dendron unit was also developed, the stage is set for preparation of larger dendrimers of this type.
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