Liquid crystal phases share some of the properties
of both isotropic liquid and crystalline solids. While the molecules
in these phases exhibit some positional and orientational order,
they also behave as fluids. This combination of properties makes
liquid crystals useful materials for electronic devices such as
liquid crystal displays (LCDs).
An important subclass of liquid crystals are discotic liquid crystals. The disc-shaped molecules that comprise these phases are capable of stacking on top of one another to form columnar phases (shown schematically to the right). While the molecules within each column are somewhat ordered with respect to one another, there is no positional correlation between molecules in different columns.
The most extensively studied class of discotic
liquid crystals are the triphenylenes (left). Columnar phases
formed by triphenylenes are electro- and photoluminescent and
exhibit quasi-1D transport of energy and charge. These systems
have attracted attention for their potential in application such
as semiconductors, organic light emitting diodes and xerographic
materials.
Our research focuses on the synthesis and study of novel discotic liquid crystals with larger aromatic cores (below). Discotic mesogens with extended aromatic cores may have some important advantages, such as smaller HOMO-LUMO gaps, lower oxidation potentials and higher intrinsic conductivities. These systems should also give rise to more highly ordered phases.
We are also investigating related structures that are structurally similar to triphenylenes, but that differ in their electronic properties. Two such examples are shown below.
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