Synthesis of a Highly Fluorescent Bis(1,4-oxaborine)pentacene.

1,4-Oxaborines represent an expansion of the current array of heteroborines. Herein, we report a new ladder-type bis(1,4-oxaborine)pentacene (BO-Pen), the backbone of which can be regarded as an isoelectronic structure of pentacene. The synthesis begins with a two-fold nucleophilic aromatic substitution followed by a ring-closing reaction. The structure was confirmed by X-ray crystallographic analysis. Compound BO-Pen is stable (even after 160 h) under ambient condition and exhibits very different electronic properties as compared to its all-carbon pentacene analogue (Pen-M). Particularly, it shows bright photoluminescence (73 % relative quantum yield) in both solution and in solid state.