2021 Fiscal Year Research-status Report
Development of Poly(diphenylacetylene) Based Novel 2D Chiral Materials with Controlled Nano-pattern
| Project/Area Number |
21K14671
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| Research Institution | Kanazawa University |
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Principal Investigator |
DAS SANDIP 金沢大学, ナノ生命科学研究所, 特任助教 (00873407)
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| Project Period (FY) |
2021-04-01 – 2023-03-31
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| Keywords | helical polymer / Atomic force microscopy |
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| Outline of Annual Research Achievements |
For the fabrication of ordered two dimensional (2D) crystal structure of chiral macromolecules on solid substrates through structural characterization of helical polymers are essential. To address the above issues, the helical structures of poly(diphenylacetylene)s (PDPAs) bearing optically active substituents linked through amide bonds and with a helicity memory have been visualised directly using high resolution atomic force microscopy (AFM). The PDPAs self-assembled into a short-range, ordered 2D monolayer on highly oriented pyrolytic graphite (HOPG) substrates upon exposure to solvent vapour, whose helical pitch and handedness (right- and left-handed) has been revealed for the first time with molecular resolution.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The structural differences between the diastereomeric PDPAs with different colours (red: P-h-poly-1-S2; yellow: P-h-poly-1-R2) and their enantiomeric counterparts (red: M-h-poly-1-R2; yellow: M-h-poly-1-S2) have been confirmed by AFM. In particular, the key structural details like helical pitch, chain to chain (C-C) distance and handedness (right or left) of the red-coloured contracted cis-cisoidal PDPAs stabilised by intramolecular H-bonding between the amide pendants have been identified precisely. The C-C and helical pitch distances of yellow polymers have also been measured accurately but the identification of helical sense is still not clear probably because the orientation of the pendant groups is not fixed by intramolecular H-bonding in the case of the stretched cis-transoidal helix. I published one paper about it
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| Strategy for Future Research Activity |
Initially, my prime target was to make 2D chiral materials of helical PDPAs with a controlled “nano-pattern” for sophisticated applications and to identify the key helical parameters. Therefore, I have tried to make close packed 2D monolayer of PDPAs on HOPG. However, the formed islands were short ranged and not atomically flat. It is my expectation that the aforementioned problems can be solved only by using long polymers. Recently, I have synthesized new PDPAs with very high molecular weight and different pendant functional groups. In future, I will try to make long ranged, ordered 2D crystal with special gap (2-5 nm) between the polymer chains using long PDPAs. Then the applications of the proposed 2D chiral materials will be explored from chiral recognition to asymmetric catalysis.
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