2.7 Columnar-diskotic liquid-crystalline structures
| Figure 9: | Hexagonal
superstructure
of poly l-lysine α-helices
in a hexagonal packing of
hexabenzocoronene
columns [48]. |
Columnar-diskotic systems, especially those based on hexabenzocoronene mesogenic units, pose
some interesting problems of structure determination from scattering data [48, 57]. Figure 9 shows
the unique superstructure of poly l-lysine α-helices hexagonally surrounded by columns of
hexabenzocoronene disks grafted to the polylysine chains. The α-helices do not distort the 2d
hexagonal lattice of the columns. They form a hexagonal superstructure with a lattice constant of
71∕2 times the one of the column packing. The positions of the hk reflections depend on one single
free parameter [48].