Thiophene-Derived Boron-Containing Dioxoborocyclic Blue-Luminescent Radicals

Luminescent radicals have attracted extensive attention due to the unique emission properties from the doublet spin state.However, luminescent radicals are predominantly chloroarylmethyl radicals that emit light in the red and near-infrared spectral regions, and the blue emitting radicals remain scarcely reported.Herein, two novel boron-containing dioxoborocyclic blue-luminescent radicals were designed and synthesized by combining dioxoborocyclic radicals with thiophene units.They were characterized by single-crystal X-ray diffraction, UV-Vis spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, and fluorescence spectroscopy in conjunction with theoretical calculations.Theoretical calculations demonstrate that both radicals 3a and 3b emit blue light from the anti-Kasha emission attributed to the effective suppression of IC pathways.Our work offers definitive proof that the boron-containing radical system functions as a highly efficient platform for expanding the diversity of short-wavelength emissive radicals.