Abstract
<jats:p> It is important to understand how a contiguous sequence of boron and nitrogen atoms in aromatics (BN sequence) modulates sp <jats:sup>2</jats:sup> /sp <jats:sup>3</jats:sup> interconversion at a boron center upon molecular binding, particularly for metal-free catalysis. However, suitable model compounds remain scarce due to limited synthetic access. Here, we report a strategy based on the Sugasawa reaction to extend the BN sequence from boron diaminonaphthalene (Bdan) with an NBN pattern to a branched sequence along two zigzag directions, embedding a BN <jats:sub>3</jats:sub> unit as a binding site. This approach is also applicable to an NCN-patterned heterophenalene analog based on diazaphenalene (DAP), affording the same 24π-electron scaffold and enabling a direct comparison of single-atom-perturbed BN sequences in molecular binding behavior. NMR analyses revealed sequence-dependent sp <jats:sup>2</jats:sup> /sp <jats:sup>3</jats:sup> interconversion of boron, consistent with solvatochromism and thermochromism. Calculations indicated that the BN sequence modulated not only the LUMO but also the delocalization circuits. A global 22π-diatropic circuit was observed in the sp <jats:sup>2</jats:sup> state of the Bdan-derived molecule, but not in the DAP-derived molecule, supporting the distinct sp <jats:sup>2</jats:sup> /sp <jats:sup>3</jats:sup> interconversion of the boron centers. This work extended BN sequences from stable heterophenalene precursors along two zigzag directions for the first time, elucidating the impact of single-atom perturbation on BN sequences. </jats:p>