Luminescent Radical‐Excimer: Excited‐State Dynamics of Luminescent Radicals in Doped Host Crystals

• Published in: Angewandte Chemie International Edition Vol. 58; no. 9; pp. 2606 - 2611
• Main Authors: Kato, Ken, Kimura, Shun, Kusamoto, Tetsuro, Nishihara, Hiroshi, Teki, Yoshio
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 25.02.2019
• Edition: International ed. in English
• Subjects: Crystals; Doped crystals; Electron states; Emissions; Excimers; excited-state dynamics; luminescence; Magnetic resonance; Mixed crystals; Monomers; Optically detected magnetic resonance; Pollution monitoring; Quantum mechanics; radicals; Signal generation; Spin dynamics; time-resolved spectroscopy; time-resolved spectroscopy; luminescence; radicals; excimers; excited-state dynamics
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201813479

The excited‐state dynamics of the photostable luminescent organic radical (3,5‐dichloro‐4‐pyridyl)bis(2,4,6‐trichlorophenyl)methyl (PyBTM) doped in a host crystal was investigated by using optically detected magnetic resonance (ODMR) and time‐resolved emission spectroscopies. In the radical system, the unpaired electron can be used as the probe for studying the electronic state and its dynamics. The mixed crystal with a high concentration of the radical showed excimer emission, together with the monomer emission. The ODMR signals were observed with opposite signs for monitoring the monomer and the excimer emissions. Based on their temperature and concentration dependencies, the excited‐state dynamics on the doped crystal and the mechanism of the excimer formation and the ODMR signal generation are discussed with the help of the quantum mechanical simulation of the excited‐state spin dynamics. The initial process of excimer formation has been clarified for the first time from the viewpoint of the spin‐dynamics. The excited‐state dynamics of a photostable luminescent organic radical doped in a host crystal was investigated by using optically detected magnetic resonance (ODMR) and time‐resolved emission spectroscopies. The initial process in excimer formation was clarified for the first time from the viewpoint of the spin dynamics.