At high angles, a weak reflection is observed at 17.4 nm
À1 (0.36 nm), representing
an ordered π-π stacking of the Tp in a liquid crystalline column. To solve the liquid
crystalline structure in sample 18, 2D XRD experiments are carried out on a shearoriented sample (see Fig. 20f). The low-angle reflections are exclusively observed on
the equator, and thus a 2D oblique symmetry is determined for the structure:
a = 5.75 nm, b = 4.36 nm, and γ = 98
. The ordered Tp π-π stacking reflection is
again observed on the meridian, suggesting a perpendicular orientation of the disks
with respect to the column axes. With further decreasing the temperature to À45
C,
the entire supermolecule crystallizes as induced by the C 12 alkyl chain crystallization. The low-angle peaks become less intensive and broader; however, the oblique
columnar feature remains intact in the sample.
Figure 21 summarizes the supramolecular self-assembly of POSS(Tp) 8 supermolecules with various spacer lengths and the tail length of C12. Although there
Fig. 21 Schematic representations of the supramolecular self-assembly of POSS(Tp) 8 supermolecules 16–18 with C 2 , C 6 , and C 10 spacer lengths, respectively. 2D unit cells are shown in
dotted lines (Miao and Zhu 2010d)
8 Supramolecular Self-Assembly of Discotic Liquid Crystalline LEGOs
243
À1 (0.36 nm), representing
an ordered π-π stacking of the Tp in a liquid crystalline column. To solve the liquid
crystalline structure in sample 18, 2D XRD experiments are carried out on a shearoriented sample (see Fig. 20f). The low-angle reflections are exclusively observed on
the equator, and thus a 2D oblique symmetry is determined for the structure:
a = 5.75 nm, b = 4.36 nm, and γ = 98
. The ordered Tp π-π stacking reflection is
again observed on the meridian, suggesting a perpendicular orientation of the disks
with respect to the column axes. With further decreasing the temperature to À45
C,
the entire supermolecule crystallizes as induced by the C 12 alkyl chain crystallization. The low-angle peaks become less intensive and broader; however, the oblique
columnar feature remains intact in the sample.
Figure 21 summarizes the supramolecular self-assembly of POSS(Tp) 8 supermolecules with various spacer lengths and the tail length of C12. Although there
Fig. 21 Schematic representations of the supramolecular self-assembly of POSS(Tp) 8 supermolecules 16–18 with C 2 , C 6 , and C 10 spacer lengths, respectively. 2D unit cells are shown in
dotted lines (Miao and Zhu 2010d)
8 Supramolecular Self-Assembly of Discotic Liquid Crystalline LEGOs
243