Luminescence, Stability, and Proton Response of an Open-Shell (3,5-Dichloro-4-pyridyl)bis(2,4,6-trichlorophenyl)methyl Radical

• Published in: Angewandte Chemie International Edition Vol. 53; no. 44; pp. 11845 - 11848
• Main Authors: Hattori, Yohei, Kusamoto, Tetsuro, Nishihara, Hiroshi
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 27-10-2014; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Corrosion resistance; density functional calculations; Electronics; Emittance; Fluorescence; Luminescence; Optical properties; Photoluminescence; photostability; Polymethyl methacrylates; protonation; Radicals; density functional calculations; protonation; luminescence; radicals; photostability
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201407362

A luminescent open‐shell organic radical with high chemical stability was synthesized. (3,5‐Dichloro‐4‐pyridyl)bis(2,4,6‐trichlorophenyl)methyl radical (PyBTM) was photoluminescent under various conditions. Fluorescence quantum yields of 0.03, 0.26, and 0.81 (the highest value reported for a stable organic radical) were obtained in chloroform, in poly(methyl methacrylate) film at room temperature, and in an EPA matrix (diethyl ether:isopentane:ethanol) at 77 K, respectively. The photostability of PyBTM is up to 115 times higher than that of the tris(2,4,6‐trichlorophenyl)methyl radical, a previously reported luminescent radical. The pyridine moiety of PyBTM acts as a proton coordination site, thereby allowing for control of the electronic and optical properties of the radical by protonation and deprotonation.
Enhanced photostability: A luminescent open‐shell organic radical with high chemical stability was synthesized. The (3,5‐dichloro‐4‐pyridyl)bis(2,4,6‐trichlorophenyl)methyl (PyBTM) radical emits fluorescent light from the lowest doublet excited state and is up to 115 times more photostable than the previously reported luminescent tris(2,4,6‐trichlorophenyl)methyl (TTM) radical.