One-shot synthesis of BN-embedded hexabenzocoronene via a dearomative triple borylation

Abstract

The missing BN isostere of coronene, 2a¹,6a¹,10b¹-triaza-2b,6b,10b-triborahexabenzo[a,d,g,j,m,p]coronene, was synthesized in a one-shot procedure from 2,4,6-tribenzhydryl-1,3,5-triazine via a dearomative triple borylation. In the crystalline state, the resulting nearly D₃-symmetric molecule forms an efficient 3D π-stacking network, with disorder observed in the B–N and C=C bonds. Density functional theory (DFT) calculations of electronic couplings predict a promising potential for applications in organic semiconducting materials. The introduction of six additional methyl groups suppressed this disorder, enabling precise bond-length alternation analysis. Notably, the incorporation of three BN units into the spoke positions of the coronene core induced a paratropic ring current in the N₃C₃ central ring, a hypsochromic shift in absorption and emission maxima, and an enhanced photoluminescence quantum yield. Furthermore, selective single and double borylations of 2,4,6-tribenzhydryl-1,3,5-triazine were demonstrated, alongside a dearomative triple borylation of its benzothiophene analog. These findings may accelerate advances in both fundamental and applied chemistry based on BN/CC isosterism.