Sulfur‐Bridged Cationic and Neutral [6]Helicenes: Chiral Trityls With Property and Stability Twists

Replacing oxygen or nitrogen bridges with sulfur in cationic [6]helicenes profoundly alters molecular shape, electronic structure, photophysics, chemical reactivity, and configurational stability. A modular strategy combining early sulfur incorporation, heteroatom‐bridge diversification, and late‐stage functionalization afforded fourteen neutral and cationic doubly bridged chiral trityl derivatives, including sulfoxide, sulfone, and sulfoximine derivatives. X‐ray diffraction showed that longer C─S bonds enforce a puckered six‐membered sulfur heterocycle, increasing helical pitch and curvature relative to O‐ and N‐bridged analogs. The sulfur‐containing carbocations are more electrophilic, displaying lower p K R+ values. Electrochemical, optical, and DFT studies show that sulfur destabilizes the HOMO while stabilizing the LUMO, narrowing the electronic gap and producing absorption up to 636 nm and emission up to 688 nm. Neutral azathia derivatives exhibit Stokes shifts up to 4823 cm −1 , consistent with substantial excited‐state relaxation. Sulfur oxidation provides orthogonal tuning, inducing blueshifts up to 66 nm in absorption and 124 nm in emission. CSP‐HPLC resolution enabled electronic circular dichroism (ECD) and circularly polarized luminescence (CPL) studies, including rare bisignate CPL consistent with dual‐state emission. Despite stronger geometric distortion, the cations racemize faster than oxygen and nitrogen analogs, supporting a nucleophile‐assisted pathway. Overall, sulfur bridging emerges as a powerful alternative for tunable red‐emissive helicenes with distinctive structural and photophysical responses.