Chemistry Reference
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Fig. 7
Comparison of laterally appended bimesogens and dimesogens with the parent
monomers
BB bimesogens,
9
and
10
were found to exhibit higher clearing points than
the parent monomers, and the AB dimesogen,
11
,wasfoundtoformaglass
at low temperature rather than recrystallize. This is a very interesting result
as it demonstrates that by introducing dissymmetry into molecular architec-
ture a material can be effectively prevented from recrystallizing. In addition,
in all cases laterally appending the mesogens to the linking group results in
the formation of nematic phases in preference to any other mesophase. This
result holds true for many other systems, including dendritic liquid crystals
and side-chain liquid crystal polymers (SCLCPs).
With trimeric supermolecular materials the situation becomes more com-
plicated because not only are there linearly and laterally linked possible struc-
tures, but also there are structures where the mesogenic units could be linked
to a central point, creating a “molecular knot”. In a similar way, tetra-, penta-,
etc., substituted supermolecules can be created.
Typically tri-, tetra-, penta-, etc., substituted supermolecules are used as
dendrons in the formation of dendritic liquid crystals. Figure 8 shows an
example of a dendron that was created to attach to a scaffold in order to
prepare a dendromesogen [25]. In this case, three cyanobiphenyl mesogens
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