Electronic and Photophysical Properties of 9,10-Anthrylene-Bridged B-π-N Donor-Acceptor Molecules with Solid-State Emission in the Yellow to Red Region.

9,10-Anthrylene-bridged triarylborane-triarylamine donor-acceptor compounds were prepared to examine the influence of the bulky π-bridge on the electronic and photophysical properties of the compounds, with the aim of realizing their solid-state emission. The intramolecular charge-transfer (ICT) absorption and emission between the vacant p orbital on the boron center, p(B), and occupied p orbital on the nitrogen center, p(N), through the π orbital of the anthrylene, π(anthrylene), were observed, and it was demonstrated that the HOMO-LUMO gap decreased with increasing number of introduced anthrylene units because of the effective lowering of LUMO originating from the p(B)-π(anthrylene) orbital interaction. The compounds exhibited solid-state emission with emission maxima at 560 nm and 643 nm, respectively, in the yellow to red region, with the corresponding absolute solid-state quantum yield of 18 % and 31 %, as a result of the combination of the highly congested structure originating from the anthrylene π-bridge and the introduction of bulky tert-butyl protecting groups.