Luminescent Donor‐Acceptor Radical With Propeller Chirality: Bright and Photostable Red Circularly Polarized Luminescence and Whispering Gallery Mode Resonance
Abstract
ABSTRACT Luminescent radicals are an emerging class of materials for organic electronics, bioimaging, and quantum applications. Circularly polarized luminescence (CPL) from luminescent radicals with propeller‐type chirality remains challenging because it is difficult to simultaneously achieve high photoluminescence quantum yield (PLQY), high stability, and high racemization barriers. A series of brominated chiral luminescent radicals, CzTTBrM, 2CzTTBrM, and 3CzTTBrM, was obtained by attaching carbazole donors to TTBrM. The donor‐acceptor‐type design induces red to near‐infrared (NIR) emission via charge transfer (CT) excited states with remarkably high PLQY (up to 76%) and high photostability. The new radicals possess high racemization barriers (Δ G ‡ (353K) = 27.9–29.1 kcal/mol), allowing the isolation of enantiopure compounds at room temperature. The enantiopure radicals exhibit CPL with broad emission across the red to NIR range (650–800 nm) and display B CPL values (0.76–1.1), nearly one order of magnitude higher than that of TTBrM (B CPL = 0.16). Moreover, doping these radicals into polystyrene microspheres produces whispering gallery mode (WGM) resonances, marking the first observation of WGM emission from luminescent radicals. This strategy establishes a versatile platform for integrating spin, chirality, and luminescence, offering new opportunities for applications in electroluminescence, bioimaging, and quantum photonics.
Article Details
Authors (15)
Kazuhiro Nakamura
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University 1 , 6-1 Kasuga-Koen, Kasuga-shi, Fukuoka 816-8580,
Kenshiro Matsuda
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University 1 , 6-1 Kasuga-Koen, Kasuga-shi, Fukuoka 816-8580,
Kosuke Anraku
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University 1 , 6-1 Kasuga-Koen, Kasuga-shi, Fukuoka 816-8580,
Keiko Yamaoka
Institute for Materials Chemistry and Engineering, Kyushu University 4 , 6-1 Kasuga-Koen, Kasuga-shi, Fukuoka 816-8580,
Taisuke Matsumoto
Institute for Materials Chemistry and Engineering Kyushu University Kasuga Japan
Fumitaka Ishiwari
Takeaki Zaima
Fukui Institute for Fundamental Chemistry, Kyoto University 1 , Takano Nishibiraki-cho 34-4, Sakyo-ku, Kyoto 606-8103,
Wataru Ota
MOLFEX, Inc., 34-4 Takano Nishibiraki-cho, Sakyo-ku, Kyoto 606-8103, Japan
Emiko Fujiwara
Fukui Institute for Fundamental Chemistry, Kyoto University 2 , Takano Nishibiraki-cho 34-4, Sakyo-ku, Kyoto 606-8103,
Tohru Sato
Fukui Institute for Fundamental Chemistry
Yoshitaka Inoue
Institute of Pure and Applied Sciences University of Tsukuba Tsukuba Japan
Soh Kushida
Department of Materials Science, Institute of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan
Yohei Yamamoto
Department of Materials Science, Institute of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan
Takuya Hosokai
National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST) 5 , Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565,
Ken Albrecht
Institute for Materials Chemistry and Engineering, Kyushu University 4 , 6-1 Kasuga-Koen, Kasuga-shi, Fukuoka 816-8580,