Chemistry Reference
In-Depth Information
FIGURE 9.6
Chemical structures of (a) polyphenylene dendrimer with an anthracene
core [39]. (b) Polytriphenylene dendrimer [41].
inactive materials (PP backbone) was greatly enhanced. The highly congested
backbone results in large torsional angle and thus electronic decoupling among
triphenylene units. Therefore, the PLof thin filmof the dendrimer showed only a small
red-shift, and retained a high LQY. However, DLED device made from this series of
dendrimers only showed moderate performance, which was partly explained by the
mismatch of HOMO energy level at the interface of the electrode and the active
material.
9.2.2.4 Other Dendrimers Yamamoto and coworkers have reported DLED de-
vices based on their phenylazomethine dendrimers [42]. Both symmetric and
asymmetric dendrimers were tested, and the influence of incorporation of metal ions
was discussed. Other examples include phenothiazine dendrimers [43] and oligo-
fluorene dendrimers [44].
9.2.2.5 Truxene-Based Dendrimers A common challenge in synthesizing shape-
persistent conjugated dendrimers is their low solubility, which may cause incomplete
transformation in coupling reactions and difficulty in purification. For divergent
synthetic strategy, high-generation dendrimers are especially hard to obtain due to the
complexity in purification. For convergent synthetic strategy, solubilizing groups
have to be incorporated at the periphery of the dendron, but they do so at the expense of
blocking the position for further functionalization.
