Design, Synthesis and Hydrogen Bonding of B 3 N 6 ‐[4]Triangulene

Abstract Replacement of the allylic C=C−C unit with a N−B−N unit at each of the three zigzag edges of [4]triangulene gives rise to B 3 N 6 ‐[4]triangulene, which is envisioned to represent a key structural unit of a new hypothetical boron carbon nitride (BC 4 N). A tert ‐butylated B 3 N 6 ‐[4]triangulene has been successfully synthesized by three‐fold nitrogen‐directed borylation, and the X‐ray crystallographic analysis indicates that its slightly bent triangular polycyclic framework can be viewed as a 1,3,5‐triphenylbenzene connected by three 4π‐electron N−B−N units. The HN−B−NH moiety provides a dual hydrogen‐bond donor, which forms H‐bonds with halide or carboxylate anions in solution, and form DD‐AA hydrogen‐bond arrays with 2,7‐di( tert ‐butyl)‐pyrene‐4,5,9,10‐tetraone in the co‐crystal. Moreover, the blue fluorescence of B 3 N 6 ‐[4]triangulene in solution is responsive to binding p ‐nitrobenzoate anion through hydrogen bonds.