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arXiv · 2103.12713

Synthesis and Thin Films of Thermally Robust Quartet (S = 3/2) Ground State Triradical

Chan Shu·Maren Pink·Tobias Junghoefer·Elke Nadler·Suchada Rajca·Maria Benedetta Casu·Andrzej Rajca
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Abstract

High spin (S=3/2) organic triradicals may offer enhanced properties with respect to several emerging technologies, but those synthesized to date typically exhibit small doublet quartet energy gaps and/or possess limited thermal stability and processability. We report a quartet ground state triradical 3, synthesized by a Pd(0)-catalyzed radical-radical cross-coupling reaction, which possesses two doublet-quartet energy gaps, DeltaEDQ ~ 0.2-0.3 kcal mol-1 and DealtaEDQ2 ~ 1.2-1.8 kcal mol-1. The triradical has a 70+% population of the quartet ground state at room temperature, and good thermal stability with onset of decomposition at > 160 {\deg}C under inert atmosphere. Magnetic properties of 3 are characterized by SQUID magnetometry in polystyrene glass and by quantitative EPR spectroscopy. Triradical 3 is evaporated under ultra-high vacuum to form thin films of intact triradicals on silicon substrate, as confirmed by high resolution X-ray photoelectron spectroscopy. AFM and SEM images of the around 1 nm thick films indicate that the triradical molecules form islands on the substrate. The films are stable under ultra-high vacuum for at least 17 h but show onset of decomposition after 4 h at ambient conditions. The drop-cast films are less prone to degradation in air and have longer lifetime.

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Chan Shu, Maren Pink, Tobias Junghoefer, Elke Nadler, Suchada Rajca, Maria Benedetta Casu, Andrzej Rajca. 2021-03-23. Synthesis and Thin Films of Thermally Robust Quartet (S = 3/2) Ground State Triradical. https://arxiv.org/abs/2103.12713

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