Boron has an empty p orbital, which can accept electrons and participate in π–p conjugation when boron is incorporated into a cyclic skeleton. Such structures play an increasingly important role in the emerging field of optoelectronics.

Shigehiro Yamaguchi, Nagoya University, Japan, and co-workers have investigated the π conjugation properties of a series of diarene-fused boron heterocycles containing B–B bonds. Their approach utilized experimental methods such as absorption spectroscopy and cyclic voltammetry as well as theoretical quantum chemical methods. The two-electron-reduced dianions are aromatic 6 π electron species that exhibit countercation-dependent absorption spectra.

The results suggest that the electronic properties of these systems can be tuned and provide deep insight into the fundamental nature of boron-containing π-conjugated systems.

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• Elucidation of π-Conjugation Modes in Diarene-Fused 1,2-Dihydro-1,2-diborin Dianions,
  T. Araki, A. Wakamiya, K. Mori, S. Yamaguchi,
  Chem. Asian J. 2012.
  DOI: 10.1002/asia.201200055