enantiopure CF7 and racemic CF8 are good gelators, while racemic
CF7 and enantiopure CF8 are too crystalline. According to the
model derived from the VCD results, the cyclohexyl rings of
gelators were stacked as a central core with all trans-perfluorinated
chains ejecting outwards. Thus the observed reversal of chirality
effects might be rationalized in terms of the terminal effects of
perfluorinated chains on the inter-aggregate interactions. The main
influence of the elongation of one –CF2– unit was the decrease in
cohesion energy among the racemic aggregates, leading to the
increase in gelation ability of racemic CF8. Similar effects of the
end group of an alkyl chain on cohesion energy were reported
previously.12
Notes and references
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Another notable feature in CF8 was the formation of
helically coiled fibrils at ee = 0.2 (see ESIw)–0.4 (Fig. 2(c)
and (d)). Helicity with a pitch less than 300 nm was related to
the absolute configuration of the major enantiomeric components.
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homochiral aggregates maintained their intensity throughout the
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disappeared. In other words, the generation of helically coiled
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In the present case, it is noted that no helical fibril was formed
at ee larger than 0.8.
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c
3862 Chem. Commun., 2012, 48, 3860–3862
This journal is The Royal Society of Chemistry 2012