Highly Luminescent Carbazole-functionalized Tris(tribromophenyl)methyl Radicals with Stable Circularly Polarized Photoluminescence

Brominated trityl radicals form stable enantiomers and are promising candidates for molecular qubits in spintronic and quantum technological applications, due to their long spin coherence times. However, their inherently weak photoluminescence (ϕ < 3 %) limits optical spin readout. Here, we report the first synthesis of three carbazolefunctionalized tris(2,4,6-tribromophenyl)methyl (TTBrM) radicals via Buchwald-Hartwig cross-coupling. These chiral open-shell emitters exhibit remarkably high photoluminescence quantum yields of up to ϕ = 72%, comparable to their chlorinated analogues, with red-shifted emission (λ PL = 646-688 nm), due to enhanced charge-transfer character. Enantiomeric resolution via chiral chromatography yields stable atropisomers (T rac > 90 °C) with strong circular dichroism (CD) and circularly polarized luminescence (CPL) showing dissymmetry factors (gabs, glum) of order 10⁻⁴, originating from the trityl propeller core. EPR confirms spin localization on the trityl unit (g ≈ 2.006), while donor methylation improves photostability (t 1/2 up to 49 min) and modestly extended phase memory times (T m = 1.49-1.68 µs). These bright, chiral TTBrM radicals represent a significant advance toward stable molecular qubits with efficient optical spin readout for quantum technologies.