Stable Boron-Containing Blue-Photoluminescent Radicals
<div>It is highly urgent to develop synthetic strategies to make new category of stable luminescent radicals with desired emission wavelength. In this study, we have isolated two dioxoborocyclic radicals ( <b>3</b> and <b>4</b> ) by a direct sy nthetic rou te. They were charac terized by UV, EPR spectroscopy and SQUID measurements. Their structures were obtained by single crystal X ray diffraction. Both radicals produce blue photoluminescence (458 nm for <b>3</b> and 478 nm for <b>4</b> ) by radiative decay from higher excited states (D<sub>2</sub>/D<sub>3</sub>) to the ground state (D<sub>0</sub>) based on theoretical calculation, breaking Kasha rule. The work records a new kind of radical emitters and the first stable radicals with blue emission bands.</div>