Based on the above results, we conclude that in addition to the H-bonding, the
relative length of the spacer with respect to the alkyl arms in Tps also determines the
supramolecular self-assembly of the amide-linked Py(Tp) 4 supermolecules. Only
when the spacer is shorter than the alkyl chains can the alkyl chain in the Tps fill up
the empty space between adjacent Tps in a Py(Tp) 4 supermolecule. As a result, the
whole supermolecule adopts an ellipsoid (or rounded) shape, which is able to selfassemble into a columnar liquid crystalline phase (see the top panel in Fig. 17).
Otherwise (i.e., the spacer is similar to or longer than the alkyl arms in Tps), the
empty space between adjacent Tps in a Py(Tp) 4 molecule cannot be filled, and thus
the supermolecule will adopt a rectangular shape with two adjacent Tps align
together at one side and the other two at the other side of the Py core during the
H-bond-assisted self-assembly. Consequently, a lamello-columnar phase will be
resulted (e.g., sample 12 at 110
C; see the bottom panel in Fig. 17).
Self-assembly of Disk-Cube Liquid Crystalline Supermolecules
In addition to doubly discotic supermolecules, disk-cube supermolecules based on
Tp and polyhedral oligomeric silsesquioxane (POSS), POSS(Tp) 8 , are also synthesized (Miao and Zhu 2010d). The chemical structures with different spacer and tail
lengths are shown in Scheme 4. The thermal behavior of these POSS(Tp) 8
Fig. 17 Molecular packing schemes for the samples 11 into a columnar structure and samples 9,
10, and 12 into a lamellar structure (Miao and Zhu 2010c)
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L. Zhu
relative length of the spacer with respect to the alkyl arms in Tps also determines the
supramolecular self-assembly of the amide-linked Py(Tp) 4 supermolecules. Only
when the spacer is shorter than the alkyl chains can the alkyl chain in the Tps fill up
the empty space between adjacent Tps in a Py(Tp) 4 supermolecule. As a result, the
whole supermolecule adopts an ellipsoid (or rounded) shape, which is able to selfassemble into a columnar liquid crystalline phase (see the top panel in Fig. 17).
Otherwise (i.e., the spacer is similar to or longer than the alkyl arms in Tps), the
empty space between adjacent Tps in a Py(Tp) 4 molecule cannot be filled, and thus
the supermolecule will adopt a rectangular shape with two adjacent Tps align
together at one side and the other two at the other side of the Py core during the
H-bond-assisted self-assembly. Consequently, a lamello-columnar phase will be
resulted (e.g., sample 12 at 110
C; see the bottom panel in Fig. 17).
Self-assembly of Disk-Cube Liquid Crystalline Supermolecules
In addition to doubly discotic supermolecules, disk-cube supermolecules based on
Tp and polyhedral oligomeric silsesquioxane (POSS), POSS(Tp) 8 , are also synthesized (Miao and Zhu 2010d). The chemical structures with different spacer and tail
lengths are shown in Scheme 4. The thermal behavior of these POSS(Tp) 8
Fig. 17 Molecular packing schemes for the samples 11 into a columnar structure and samples 9,
10, and 12 into a lamellar structure (Miao and Zhu 2010c)
238
L. Zhu