Helicene‐Grafted Silica Nanoparticles Capture Hetero‐Double‐Helix Intermediates during Self‐Assembly Gelation |
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Authors: | Masamichi Miyagawa Prof?Dr Masahiko Yamaguchi |
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Institution: | Department of Organic Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, 6‐3 Aoba, Sendai 980‐8578 (Japan), Fax: (+81)?22‐795‐6811 |
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Abstract: | A mixture of a pseudoenantiomeric ethynylhelicene (M)‐tetramer and a (P)‐pentamer forms a hetero‐double‐helix in a solution, which self‐assembles and gelates solvents. When gelation was conducted in the presence of chiral silica (P)‐nanoparticles grafted with (P)‐helicene, the resulting hetero‐double‐helix intermediate was adsorbed on the (P)‐nanoparticles, and was removed from the solution by aggregation and precipitation. The resulting precipitates contained only the hetero‐double‐helix, not random coil or clusters of the hetero‐double‐helix. (P)‐Nanoparticles did not extract the hetero‐double‐helix from the self‐assembly gels. The hetero‐double‐helix was then isolated by liberating it from the precipitates in 2‐bromopropionic acid, and was crystallized from the solution. The crystalline hetero‐double‐helices were isolated for several other combinations of pseudoenantiomeric ethynylhelicene oligomers. |
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Keywords: | gels nanoparticles precipitation reactive intermediate reaction mechanisms self‐assembly |
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