Boron‐Doped Polycyclic Aromatic Hydrocarbons (B‐PAHs): Synthesis, Properties, and Applications

Abstract

Inspired by the doping approach used in silicon technology to building inorganic semiconductors, in this chapter we tackle the emerging approach in organic synthesis of exploiting the replacement of carbon atoms with isolobal heteroatoms. Capitalizing on the idea for which the insertion of heteroatoms of graphitic nanostructure preserves the planar geometry of the π‐scaffold, one could envisage to tune the optoelectronic properties of π‐conjugated molecular materials by the only insertion of heteroatoms. Herein, we discuss all B‐containing rings that can be envisaged to construct doped π‐conjugated structures integrating a graphenoid framework. In the first section, we guide the reader through the synthesis, properties, and applications of the most relevant examples of B‐doped PAHs, in which one or more sp 2 ‐hybridized carbon atoms have been replaced by B atoms through the formation of the CB bond. Past and recent synthetic developments of aromatic and nonaromatic B‐doped ring, i.e., boracycle, are discussed. B‐PAHs are amenable to be classified by ring size of the boracycle, that is, three‐, four‐, five‐, six‐, or seven‐membered rings. In a second avenue, we focused the attention on the use of the boron–nitrogen (BN) pair site as isoelectronic and isostructural doping units replacing CC bonds in PAHs. While three‐ and four‐membered rings containing BN couples are known but not extensively explored, five‐ and six‐membered rings are certainly the most studied structural π‐conjugated motifs. In the last section, the heart of the discussion is centered on B‐PAHs containing BO bonds, mainly in five‐ and six‐membered rings.

Aromaticity transfer in an annulated 1,4,2-diazaborole: facile access to Cs symmetric 1,4,2,5-diazadiborinines

“…Boron-containing heterocyclic compounds have received rapidly increasing attention in recent years due to their ability to activate inert bonds, 1–9 and their tuneable photophysical properties have led to applications in optoelectronic devices. 10–19 In particular, diazadiborinines, – six-membered aromatic rings featuring two C, two B, and two N atoms – have demonstrated themselves to be a privileged subclass of B-heterocycles (Scheme 1a). They have demonstrated a diverse array of challenging bond activations including H–H, C–H, C–F, and C–C bonds, 20–29 and have been very recently applied as organocatalysts in hydroboration and N -formylation reactions.…”