Multi‐Input/Multi‐Output Molecular Response System Based on the Dynamic Redox Behavior of 3,3,4,4‐Tetraaryldihydro[5]helicene Derivatives: Reversible Formation/Destruction of Chiral Fluorophore and Modulation of Chiroptical Properties by Solvent Polarity

3,3,4,4‐Tetaaryldihydro5]helicenes ( 1 ) and 1,1′‐binaphthyl‐2,2′‐diylbis(diarylcarbenium)s ( 2 ²⁺) can be reversibly interconverted upon electron transfer, which is accompanied by a vivid color change (electrochromism) as well as by the formation/cleavage of a C? C bond (“dynamic redox behavior”). Because only the neutral donor 1 exhibits strong fluorescence, electrochemical input can further modify the fluorescent properties of the pair. Due to the configurational stability of the helicity in 1 and axial chirality in 2 ²⁺, the redox reaction of optically pure material proceeds stereospecifically, which induces a chiroptical change such as circular dichroism (CD) as an additional output. The CD spectra of dications 2 ²⁺ exhibit solvent dependency (chiro‐solvatochromism), which is accompanied by solvatochromic behavior based on the π–π interaction of the two cationic chromophores as well as coordinative interaction of the Lewis basic solvent to the Lewis acidic triarylcarbenium moieties. Thus, the present system is endowed with multi‐input functionality for modifying multiple output signals.