2006 Fiscal Year Final Research Report Summary
Cationic self-assembled monolayers composed of gemini-structured sulfur compounds on gold : A new approach to control ionic functions on surfaces and chiral detection.
| Project/Area Number |
15310098
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nanomaterials/Nanobioscience
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| Research Institution | Tokyo Institute of Technology (2005-2006)
National Institute of Advanced Industrial Science and Technology (2003-2004) |
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Principal Investigator |
TAMADA Kaoru Tokyo Institute of Technology, Department of Electronic Chemistry, Associate Professor, 大学院総合理工学研究科, 助教授 (80357483)
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| Co-Investigator(Kenkyū-buntansha) |
ISHII Noriyuki Biological Information Research Center, Senior Scientist, 生物情報解析研究センター, 主任研究員 (10261174)
MIYAZAKI Kentaro Institute for Biological Resources and Functions, AIST, Group leader, 生物機能工学研究部門, グループ長 (60344123)
HARA Masahiko Tokyo Institute of Technology, Department of Electronic Chemistry, Professor, 大学院総合理工学研究科, 教授 (50181003)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Gemini molecules / Chiral recognition / Optical resolution / Surface plasmon / Self-assembled monolayers / Thiol derivatives / Tartaric acid / Quaternary ammonium |
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| Research Abstract |
Cationic self-assembled monolayers (SAMs) composed of quaternary ammonium (QA) sulfur derivatives have been synthesized to control the distance between charged head groups on gold substrates. Two molecules bearing resembling molecular structures, "gemini"-structured didodecyl dithiol (HS-gQA-SH) and didodecyl disulfide (QA-SS-QA) or dodecyl thiol (QA-SH), were utilized in this study, and the formation and structure of the SAMs were characterized by surface plasmon resonance spectroscopy (SPR), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared-reflection adsorption spectroscopy (FTIR-RAS) and Kelvin Probe method. In the HS-gQA-SH SAM, the orientation and distance between QA groups are specified by the covalent bonding with ethylene spacer, while those of the QA-SS-QA SAM and QA-SH are determined by the electric repulsion between charged head groups, that is, QA groups in the QA-SS-QA SAM and QA-SH are more randomly located, being more distant than with those in the HS-gQA-SH SAM. Contact potential difference data obtained by KP suggested the existence of much larger dipoles on HS-gQA-SH SAM compared with on QA-SH SAM as a result of higher density of the functional group.
We found that L-tartaric acid (TA), a probe molecule with two carboxyl groups having the distance of an ethylene unit, exhibits a strong affinity on the HS-gQA-SH SAM. In contrast, a specific binding was little observed on the QA-SS-QA SAM and QA-SH SAM. We demonstrate the crystal growth of L-TA on TA enantiomers (L or D-TA) immobilized QA-SH SAM, and found selective crystal growth on the same chiral surfaces (L-TA on L-TA). We have also tried one-step synthesis of gold nanoparticles capped by the QA-SS-QA SAM in this study.
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