length of C12 in the Tp arms, Py and Tp are strongly coupled together, and thus Py
disks do not tilt along the a-axis in order to form regular π-π stacks (see Fig. 9b).
Assuming the C12Tp diameter is 2.5 nm, the tilt angle for the Tp is calculated to be
ca. 53
. The measured density was 0.904 g/cm
3 , suggesting only one supermolecule
per unit cell. The theoretical density was calculated to be 0.92 g/cm
3 , which is close
to the observed one.
While the above Py(Tp) 2 supermolecules only show crystalline structures, it is
possible to induce liquid crystalline structures for Py(Tp) 4 supermolecules, as shown
in Scheme 3. Two series are synthesized (Miao and Zhu 2010c): an amide series
9–12 and an ester series 13–16. The thermal properties are studied by DSC and
results are shown in Fig. 10. Detailed phase transitions are summarized in Table 3.
The amide series 9–12 are capable to exhibit liquid crystalline phases, whereas the
ester series 13–16 only show either glass phase or crystalline structure. This result
Fig. 8 2D XRD patterns on shear-oriented Py(Tp) 2 : (a) sample 5, (b) sample 6, (c) sample 7, and
(d) sample 8 (Miao and Zhu 2010b)
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L. Zhu