Color-tunable donor-acceptor-type B-embedded dioxygen-bridged π-conjugated molecules: Synthesis, structures, and optical properties

Three novel donor-acceptor-type B-embedded dioxygen-bridged π-conjugated molecules (BO-CZ, BO-N and BO-NO) featuring different electron donors have been synthesized by Suzuki-Miyaura C–C coupling. Single crystal structures show that both BO-CZ and BO-N exhibit obvious π-π interactions in solid state due to the good planarity of the B-embedded dioxygen-bridged π-conjugated unit. More importantly, by controlling different electron donor units, the luminescence color of these compounds can be changed from deep blue to yellow with high luminescence quantum efficiency, up to close to 100%. Notably, the deep-blue-emitting molecule BO-CZ in film exhibits an ultrahigh color purity with a very narrow full width at half maximum (FWHM = 36 nm) and CIE coordinates (0.164, 0.019). Interestingly, these donor-acceptor-type boron-containing molecules with Lewis acidity can interact with Lewis bases (pyridine and DMAP) and induce interesting optical changes.