A nonconjugated radical polymer with stable red luminescence in the solid state

Authors：Wang, Zhaoyu; Zou, Xinhui; Xie, Yi; Zhang, Haoke; Hu, Lianrui; Chan, Christopher C. S.; Zhang, Ruoyao; Guo, Jing; Kwok, Ryan T. K.; Lam, Jacky W. Y.; Williams, Ian D.; Zeng, Zebing; Wong, Kam Sing; Sherrill, C. David; Ye, Ruquan^*; Tang, Ben Zhong^*

Source：Materials Horizons, 2022, 9(10): 2564-2571.

DOI：10.1039/d2mh00808d

• LIGHT-EMITTING-DIODES
• CARBON FREE-RADICALS
• FLUORESCENCE
• MECHANISM
• SCAVENGER
• OXIDATION
• EMISSION
• AEQUORIN
• PROTEIN

Organic radicals are unstable and stable radicals usually display non-luminescent properties. Luminescent radicals possess the all-in-one properties of optoelectronics, electronics, and magnetics. To date, the reported structures of luminescent radicals are limited to triphenylmethyl radical derivatives and their analogues, which are stabilized with extended pi-conjugation. Here, we demonstrate the first example of a nonconjugated luminescent radical. In spite of the lack of delocalized pi-stabilization, the radical polymer readily emits red luminescence in the solid state. A traditional luminescent quencher, 2,2,6,6-tetramethylpiperidin-1-yl turned into a red chromophore when grafted onto a polymer backbone. Experimental data confirm that the emission is associated with the nitroxide radicals and is also affected by the packing of the polymer. This work discloses a novel class of luminescent radicals and a distinctive pathway for luminescence from open-shell materials.