| Summary: | Three new amino-<i>s</i>-triazine-based dendrons, <b>1a</b>, <b>1b</b>, and <b>1c</b>, containing an aryl-CN moiety in the dendritic skeleton were prepared in 72–81% yields (<b>1a</b>: R<sup>1</sup> = − N(<i>n</i>-C<sub>8</sub>H<sub>17</sub>)<sub>2</sub>, R<sup>2</sup> = <i>n</i>-OC<sub>8</sub>H<sub>17</sub>, <b>1b</b>: R<sup>1</sup> = R<sup>2</sup> = − N(<i>n</i>-C<sub>8</sub>H<sub>17</sub>)<sub>2</sub>, <b>1c</b>: R<sup>1</sup> = − N(<i>n</i>-C<sub>8</sub>H<sub>17</sub>)<sub>2</sub>, R<sup>2</sup> = − N(<i>n</i>-C<sub>4</sub>H<sub>9</sub>)<sub>2</sub>). Dendrons <b>1a</b> with N(<i>n</i>-C<sub>8</sub>H<sub>17</sub>)<sub>2</sub> and <i>n</i>-OC<sub>8</sub>H<sub>17</sub> peripheral substituents, surprisingly, did not show any mesogenic phase during the thermal process. However, non-mesogenic <b>1a</b> can be converted to mesogenic <b>1b</b> or <b>1c</b> by eliminating the peripheral dipole arising from the alkoxy substituent; dendron <b>1b</b> only comprising the same N(<i>n</i>-C<sub>8</sub>H<sub>17</sub>)<sub>2</sub> peripheral groups showed a ~25 °C mesogenic range on heating and ~108 °C mesogenic range on cooling. In contrast, dendron <b>1c</b> possessing different N(<i>n</i>-C<sub>m</sub>H<sub>2m+1</sub>)<sub>2</sub> (m = 8 versus m = 4) peripheral units, having similar stacking as <b>1b</b>, exhibited a columnar phase on thermal treatment, but its mesogenic range (~9 and ~66 °C on heating and cooling, respectively) was much narrower than that of <b>1b,</b> attributed to <b>1c</b>’s less flexible alkyl chains in the peripheral part of dendron. Dendron <b>1a</b> with the alkoxy substituent in the peripheral skeleton, creating additional dipole correspondingly, thus, leads to the dendritic molecules having a non-mesogenic stacking. Without the peripheral dipole for intermolecular side-by-side interaction, dendrons <b>1b</b> and <b>1c</b> exhibit a columnar phase on thermal treatment because of the vibration from the peripheral alkyl chain.
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