2000 Fiscal Year Final Research Report Summary
Design and synthesis of nanosized conjugated π-electron molecules with specific functionarity
| Project/Area Number |
10440189
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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 |
Organic chemistry
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| Research Institution | Hiroshima University |
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Principal Investigator |
OTSUBO Tetsuo Fac of Eng, Hiroshima University, Prof., 工学部, 教授 (80029884)
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| Co-Investigator(Kenkyū-buntansha) |
TAKIMIYA Kazuo Fac of Eng, Hiroshima University, Res.Ass., 工学部, 助手 (40263735)
ASO Yoshio Fac of Eng, Hiroshima University, Assoc.Prof., 工学部, 助教授 (60151065)
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| Project Period (FY) |
1998 – 2000
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| Keywords | Nanoscale molecule / Oligomer / Thiophene / Molecular wire / Molecular device / Organic functional material |
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| Research Abstract |
As one of the most promising approaches for the development of functional organic materials, nanosized conjugated oligomers are of current attention. However, only few number of well-defined nanomolecules with over 10 nm length readily manipulated by modern STM techniques have not been known. In this regard, this project has aimed at the development of extraordinarily long oligothiophenes, which correspond to monodisperse polymers. A series of oligothiophenes up to the 72-mer has been synthesized. The spectroscopic studies of the homologous series of the long oligothiophenes served to clarify the concept of an effective conjugation length of α-conjugated thiophene systems, which extends to 20-30 thiophene units. The doped-conductivity studies of these oligomers were also very helpful in elucidating the conduction mechanism of conductive polythiophenes : it turned out that the conductivities are also dependent on the conjugation length, and the effective conjugation length play a critical role in determining the charge transport of polythiophenes. In addition, the spectroscopic studies of the oxidized species led to an important conclusion that the active charge carrier species are both π-dimers and bipolarons. In an extension study, long oligothiophenes were used as a molecular wire allowing photoinduced electron- and/or energy-transfer from the donating porphyrin part to the accepting fullerene part. Furthermore, the molecular-wire behavior of sophisticated oligothiophenes was successfully applied to the oligothiophene-based photovoltaic devices.
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