BN Tetracene: Extending the Reach of BN/CC Isosterism in Acenes

The first synthesis of a tetracene
BN isostere is reported. Comparison
with its direct, all-carbon analogue reveals that the BN tetracene
isostere exhibits a lower-lying HOMO and a slightly larger optical
HOMO–LUMO gap. While all-carbon tetracenes are prone to photodecomposition,
the BN tetracene scaffold is less light sensitive, owing in part to
its much higher photoluminescence quantum yield. In the context of
this larger BN tetracene family, we introduce simple guiding principles
for predicting frontier orbital energies as a function of the position
of the BN unit within the tetracene scaffold.