For the CPL of gelator molecules in a dilute molecular state, it is similar to most
of organic molecules. However, in the design of CPL molecules with point chirality,
the distance between the chiral center and the chromophore is very important. If
the spacer between the chiral center and the chromophore is too long, you cannot
get CPL. In the case of CPL from the gelators in assemblies, another phenomenon
called aggregation caused quench (ACQ) and aggregation-induced emission (AIE)
will frequently appear, which will greatly alter the CPL of the system. These are
very important issues which should be considered in the design of the CPL-active
gelators.
As illustrated in Fig. 11.2, there are three cases for the design of gelator molecules
in order to get the CPL, similar to the formation of the supramolecular chiral
gels [18].
The first case is that the isolated gelator shows CPL and the gel showed enhanced
or diminished CPL due to the self-assembly. The second case is that the fluorophore
does not have any chiral unit. However, when co-assembled with the chiral gelator,
Fig. 11.2 Schematics of gelation induced by self-assembly of gelator (top) and three types of
gelation-induced supramolecular chirality (bottom). Chiral gels from (a) exclusive chiral gelators,
(b) the co-assembly of chiral gelator and achiral dopants, and (c) exclusive achiral gelators
[18]. Copyright 2014, The Royal Society of Chemistry
11 Circularly Polarized Luminescence from Gelator Molecules: From Isolated. . .
251
of organic molecules. However, in the design of CPL molecules with point chirality,
the distance between the chiral center and the chromophore is very important. If
the spacer between the chiral center and the chromophore is too long, you cannot
get CPL. In the case of CPL from the gelators in assemblies, another phenomenon
called aggregation caused quench (ACQ) and aggregation-induced emission (AIE)
will frequently appear, which will greatly alter the CPL of the system. These are
very important issues which should be considered in the design of the CPL-active
gelators.
As illustrated in Fig. 11.2, there are three cases for the design of gelator molecules
in order to get the CPL, similar to the formation of the supramolecular chiral
gels [18].
The first case is that the isolated gelator shows CPL and the gel showed enhanced
or diminished CPL due to the self-assembly. The second case is that the fluorophore
does not have any chiral unit. However, when co-assembled with the chiral gelator,
Fig. 11.2 Schematics of gelation induced by self-assembly of gelator (top) and three types of
gelation-induced supramolecular chirality (bottom). Chiral gels from (a) exclusive chiral gelators,
(b) the co-assembly of chiral gelator and achiral dopants, and (c) exclusive achiral gelators
[18]. Copyright 2014, The Royal Society of Chemistry
11 Circularly Polarized Luminescence from Gelator Molecules: From Isolated. . .
251