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Updated: May 17, 2026

A Novel Technique for Generating and Observing Chemiluminescence in a Biological Setting
Published on: March 9, 2017
Highly luminescent carbazole-functionalized tris(tribromophenyl)methyl radicals with stable circularly polarized
Larissa Schöneburg1, Markus Gross1, Philipp Thielert2,3
1L. Schöneburg, M. Gross, J. Zolg, Dr. M. E. Arnold, Dr. P. A. Schuster, B. Putz, Prof. Dr. A.J.C. Kuehne OC III - Institute of Organic and Macromolecular Chemistry Ulm University Albert-Einstein-Allee 11, 89081, Ulm, Germany.
Abstract:
Brominated trityl radicals form stable enantiomers and present promising candidates for molecular qubits in spintronic and quantum technologies. However, their inherently weak photoluminescence (ϕ < 3 %) limits optical spin readout. Here, we report the synthesis of three carbazole-functionalized tris(2,4,6-tribromophenyl)methyl (TTBrM) radicals via Buchwald-Hartwig cross-coupling. These chiral open-shell emitters exhibit high photoluminescence quantum yields of up to ϕ = 72%, comparable to their chlorinated analogues, with red-shifted emission (λPL = 646-688 nm) due to enhanced charge-transfer character. Enantiomeric resolution via chiral chromatography yields stable atropisomers (Trac > 90 °C) with strong circular dichroism and circularly polarized luminescence showing dissymmetry factors (gabs, glum) of order 10⁻⁴. EPR confirms spin localization on the trityl unit (g ≈ 2.006) with phase memory times Tm of 1.5 - 1.6 µs, while donor methylation improves photostability (t1/2 up to 49 min). These bright, chiral TTBrM derivatives offer a significant advance toward stable molecular qubits.
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