Tris(4-Halo-2,6-Difluorophenyl)Methyl Radicals Exhibiting Green Doublet Emission

Accessing high-energy doublet excited states while maintaining radical persistence remains a major challenge for luminescent organic radicals, with stable radicals predominantly emitting from the red to near-infrared region. Herein, we report two stable fluorinated trityl radicals, tris(4-chloro-2,6-difluorophenyl)methyl (CDFTM) and tris(4-bromo-2,6-difluorophenyl)methyl (BDFTM), based on tris(4-halo-2,6-difluorophenyl)methyl frameworks, which exhibit intrinsic green doublet emission at 527 and 529 nm, respectively. Their molecular structures and open-shell nature were unambiguously established by spectroscopic and crystallographic analyses. Compared with the benchmark trityl radical tris(2,4,6-trichlorophenyl)methyl (TTM), these fluorinated radicals adopt more planarized propeller-like conformations and exhibit pronounced blue shifts in both absorption and emission. Detailed photophysical investigations confirm that the green emission originates from the radical species themselves. Theoretical calculations further reveal an orbital-selective reorganization induced by fluorination, providing an electronic basis for the higher-energy doublet state and spectral blue shift. Stability studies further identify peroxide formation as a major degradation pathway, while preliminary electroluminescent devices demonstrate the proof-of-concept applicability of these radicals as doublet emitters. Overall, this work establishes a selective fluorination strategy for accessing high-energy intrinsic doublet emission and provides new molecular design insights for short-wavelength luminescent radicals.