Tuning the Electro-Optical Properties of Mixed-Halide Trityl Radicals Bearing para-Brominated Positions through Halogen Substitution

In this work, the synthesis and characterization of two new trityl radicals bearing two p-brominated positions, i. e. the 2,2′-((perchlorophenyl)methylene)bis(1,3,5-tribromobenzene) radical and the 6,6′-((perchlorophenyl)methylene)bis(3-bromo-1,2,4,5-tetrafluorobenzene) radical, are presented. Slightly modifying the strategy typically used for the synthesis of non-symmetric mixed-halide trityl radicals, we were able to considerably increase the reaction yield for the radical precursors. In addition, for the first time the electro-optical properties of a highly fluorinated trityl radical were studied, achieving the most blue-shifted emission for a trityl radical reported up to now. Quantum-chemical calculations carried out to supplement the experimental investigation support the electrochemical and spectroscopic data as well as rationalize the observed blue shift of the highly fluorinated species.