Metal-Free, Blue-Light-Mediated Radical Trifluoromethylation of Small Organic Molecules

The development of a gentle and regioselective trifluoromethylation process is necessary due to the rise in organofluorine compounds, notably the inclusion of a -CF₃ group in organic molecules for the pharmaceutical and materials sectors. This work presents novel examples of luminescent procarbenic purely organic photocatalysts (C1-C3) that exhibited low-negative irreversible reduction events (E_Red=-0.86 V, -0.85 V and -0.68 V vs SCE for C1, C2 & C3, respectively) and strong ligand-to-ligand charge transfer absorption in the UV region (λ_abs~280 nm). At room temperature (RT), both photocatalysts displayed deep-blue ¹LC emission in the 353-373 nm region. These photocatalysts were found to be strong photo-oxidants (E_C(II)*/C(I)=2.54 V, 2.65 V and 2.63 V vs SCE for C1, C2 and C3, respectively) and were employed as low-cost, metal and additive-free photocatalysts for the regioselective mono(trifluoromethylation) of polyaromatic hydrocarbons (PAHs) and small organic molecules in good yields (~42-82 %).