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arXiv · 2608.21037

Sulfur-rich Spirofluorene-Bridged N Heterotriangulene Redox-Active Polymers

Angelina Jocic·Tom Wickenhäuser·Sebastian Lindenthal·Alexander Welle·Vanessa Trouillet·Ronald Curticean·Irene Wacker·Jana Zaumseil·Rasmus R. Schröder·Rüdiger Klingeler·Milan Kivala
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Abstract

Sulfur-rich spirofluorene-bridged N-heterotriangulene (FTN) polymers featuring covalently linked oligosulfide units and a terthiophene-based analogue were synthesized via nucleophilic aromatic substitution and Stille cross-coupling polymerization. The resulting materials are amorphous, insoluble solids with high thermal stability and sulfur contents up to 25 wt%. Structural and compositional analyses by combustion analysis, ToF-SIMS, FT-IR, XPS, and solid-state NMR confirm the efficient incorporation of short oligosulfide to disulfide linkages and well-defined terthiophene units in the respective polymers. Electrochemical characterization in lithium half-cells reveals a reversible, high-voltage oxidation of the FTN unit at 3.8-4.0 V (vs. Li/Li+), accompanied by low-voltage sulfur- or terthiophene-based redox processes between 1.5-2.5 V (vs. Li/Li+). Sulfur incorporation markedly increases the theoretical and initial discharge capacities (up to 129 mA h g-1), while the sulfide conversion processes exhibit rapid fading and poor reversibility due to sulfide dissolution. In contrast, the terthiophene-linked polymer shows only transient low-voltage activity while maintaining high Coulombic efficiencies (ca. 99.7%) governed by the persistent FTN backbone redox event. Our results highlight how different redox-active linkers influence the electrochemical behavior of FTN-based polymers and provide insights into the design of functional organic cathode materials featuring multi-redox processes.

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Angelina Jocic, Tom Wickenhäuser, Sebastian Lindenthal, Alexander Welle, Vanessa Trouillet, Ronald Curticean, Irene Wacker, Jana Zaumseil, Rasmus R. Schröder, Rüdiger Klingeler, Milan Kivala. 2026-08-21. Sulfur-rich Spirofluorene-Bridged N Heterotriangulene Redox-Active Polymers. https://doi.org/10.1016/j.synthmet.2026.118233

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