Extended Tetrathiafulvalenes: Intramolecular Interactions Within 2,2′‐Biphenyl‐Bridged Fluorene‐Dithiafulvenes

Tetrathiafulvalene (TTF) is a well‐known redox‐active molecule that undergoes two reversible one‐electron oxidations to afford stable cationic species. Its redox and optical properties, as well as molecular geometry and self‐association behavior, can be systematically tuned through incorporation of a π‐conjugated framework between the two dithiole rings. Herein, we report the synthesis of novel extended TTF scaffolds in which two fluorene‐dithiafulvene units are rigidly connected via a 2,2′‐biphenyl spacer. Crystallographic, computational, and 1 H nuclear magnetic resonance (NMR) spectroscopic studies show that the neutral scaffolds take a conformation allowing for intramolecular associations between the two fluorene‐dithiafulvene units. Electrochemical studies further reveal intramolecular stabilization of radical cations owing to mixed valence dimer formation, supported by a strong near‐infrared absorption.