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Steric Control of Luminescence in Phenyl-Substituted Trityl Radicals.

Petri MurtoBiwen LiYao FuLucy E WalkerLaura BrownAndrew D BondWeixuan ZengRituparno ChowdhuryHwan-Hee ChoCraig P YuClare P GreyRichard Henry FriendHugo Bronstein
Published in: Journal of the American Chemical Society (2024)
Triphenylmethyl (trityl) radicals have shown potential for use in organic optoelectronic applications, but the design of practical trityl structures has been limited to donor/radical charge-transfer systems due to the poor luminescence of alternant symmetry hydrocarbons. Here, we circumvent the symmetry-forbidden transition of alternant hydrocarbons via excited-state symmetry breaking in a series of phenyl-substituted tris(2,4,6-trichlorophenyl)methyl (TTM) radicals. We show that 3-fold phenyl substitution enhances the emission of the TTM radical and that steric control modulates the optical properties in these systems. Simple ortho -methylphenyl substitution boosts the photoluminescence quantum efficiency from 1% (for TTM) to 65% at a peak wavelength of 612 nm (for 2-T 3 TTM) in solution. In the crystalline solid state, the neat 2-T 3 TTM radical shows a remarkably high photoluminescence quantum efficiency of 25% for emission peaking at 706 nm. This has implications in the design of aryl-substituted radical structures where the electronic coupling of the substituents influences variables such as emission, charge transfer, and spin interaction.
Keyphrases
  • solid state
  • energy transfer
  • quantum dots
  • light emitting
  • molecular docking
  • room temperature
  • molecular dynamics
  • high resolution
  • photodynamic therapy
  • climate change
  • single molecule
  • transition metal