Syntheses and Physical Properties of Cationic BN-Embedded Polycyclic Aromatic Hydrocarbons.

Cationic BN-embedded polycyclic aromatic hydrocarbons (BN-PAH+ s) were synthesized from a nitrogen-containing macrocycle via pyridine-directed tandem C-H borylation. Incorporating BN into PAH+ resulted in a remarkable hypsochromic shift due to an increase in the LUMO energy and the symmetry changes of the HOMO and LUMO. Electrophilic substitution or anion exchange of BN-PAH+ possessing tetrabromoborate as a counter anion (BN+ [BBr4 - ]) afforded air-stable BN-PAH/PAH+ s. Of these, BN+ [TfO- ] allowed reversible two-electron reduction and the formation of two-dimensional brickwork-type π-electronic ion pair with 1,2,3,4,5-pentacyanocyclopentadienyl anion, demonstrating the potential application of BN-PAH+ as electronic materials.