Competing Charge Transport Pathways: A Spirobifluorene‐Based Molecular Loop

Abstract

Abstract

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.