were detected (Fig. 11.11b). The CPL spectra detected from the four different angles
showed a same sign with similar shape in a series of evaluation, indicating that the
chirality of Rhodamine B was induced by stir on a macroscopic level. Nevertheless,
it should be noted that such CPL only can be observed during the stirring process.
Once the stirring stopped, the sample became CPL silent.
In the supramolecular gel systems, an achiral C 3 -symmetric gelator was also
found to display fascinating CPL performance (Fig. 11.12) [34]. It was found
that when the achiral gelators formed the organogels, it showed strong emission
as well as the CPL. The handedness of the CPL appeared randomly, suggesting
Fig. 11.10 Chemical structure of 10 and (a) CPL spectra for 10 before (filled circle) and after (open
circle) UV irradiation. (b) Schematics of supramolecular helical assembly of 10’s reversible helicity
inversion via a disassembly/reassembly process accompanying with E/Z photoisomerization of
azobenzene moieties. Δ ¼ heating; Ã ¼ cooling. Reproduced with permission [31]. Copyright 2012,
Wiley-VCH
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