Stable Diphenylamine-Substituted Tris(2,4,6-trichlorophenyl)methyl Radical Oligomers: Synthesis, Optical Properties, and Redox Chemistry

Abstract

Tris(2,4,6-trichlorophenyl)methyl (TTM) radical oligomers with different number of spin centers are designed and successfully synthesized through C–N/C–C coupling reaction using the diphenylamine group as building block. The strong intramolecular charge transfer (ICT) interactions endow radical oligomers with obvious absorption and emission bands in near-infrared regions. Impressively, the strong electron-deficient property of TTM core and single bond linking mode between the adjacent diphenylamine spacers greatly contribute to the formation of intramolecular isolated redox centers. Accordingly, after the treatment of chemical equivalent NO•SbF₆ oxidant, polyradicals are converted directly to the corresponding highest oxidation state along with the formation of quinoidal structure cation, which can be verified by UV spectra and single crystal analysis. This study develops a facile design rule for the construction of TTM-based polyradicals and provides the reference for oxidation process and mechanism of polyradical open shell molecules with the weak electron coupling systems.

Keywords

Tris(2,4,6-trichlorophenyl)methyl / Diphenylamine derivatives / Radical oligomers / Near-infrared emission / Redox chemistry / Radicals / Donor-acceptor systems / Dyes/pigments

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