Competing Charge Transport Pathways: A Spirobifluorene‐Based Molecular Loop

Understanding the relationship between molecular structure and charge transport remains a crucial aspect towards integrating single molecules into electronic devices, especially in systems which feature multiple conducting pathways. Here we report the synthesis of a molecular loop that incorporates a rigid 9,9′-spirobifluorene (SBF) core as a central mounting point for thiol anchoring groups and a cycloparaphenylene (CPP) backbone. The model compound is synthesized by a Suzuki–Miyaura coupling between a CPP precursor and a functionalized SBF derivative, followed by reductive aromatization of the macrocycle. The resulting macrocycles are fully characterized and enantiomerically resolved by chiral high-performance liquid chromatography (HPLC), and their chiroptical properties are investigated. Conductance measurements in a mechanically controlled break-junction (MCBJ) setup demonstrate reproducible single-molecule junction formation with two dominant conductance plateaus near 2 × 10$^{−4}$ G$_0$ and 4 × 10$^{−5}$ G$_0$, observed across different samples and applied voltages. The observed conductance features are consistent with multiple reproducible junction configurations, highlighting the molecular loop as a promising platform for studying charge transport through multiple intramolecular pathways.