Highly photostable luminescent open-shell (3,5-dihalo-4-pyridyl)bis(2,4,6-trichlorophenyl)methyl radicals: significant effects of halogen atoms on their photophysical and photochemical properties

Novel luminescent radicals, Br2PyBTM and F2PyBTM were synthesized and their structures, spectroscopic properties, photostability, and electronic structures were compared with those of Cl2PyBTM. Br2PyBTM showed the highest photostability and F2PyBTM displayed the highest photoluminescence quantum yield of the three radicals.