Here, we report the first redox-active chiral dopant D, which electrically alters its helical twisting power (HTP) for a cholesteric liquid crystalline (LC) medium and quickly changes the reflection color.D is composed of an axially chiral binaphthyl unit in conjunction with a redox-active ferrocene unit. A cholesteric LC phase of 4'-pentyloxy-4-cyanobiphenyl, doped with D (3.0 mol %), developed a blue reflection color. When nitrosyl tetrafluoroborate, a one-electron oxidant, was added to this cholesteric LC phase,D was oxidized to decrease its original HTP value by 13%, so that a green reflection color was developed. In the presence of a supporting electrolyte, the reflection color was electrochemically modulated using a sandwich-type glass cell with indium tin oxide electrodes. In quick response to the applied voltage of +1.5 V, the reflection color changed from blue to green within 0.4 s. When 0 V was applied, the reflection color returned to its original blue color. The D-doped cholesteric LC is characterized by its fastest electrochemical response and lowest operating voltage among those reported for electrically driven cholesteric LC devices.

A S 6-symmetric triarylamine-based macrocycle (i.e., hexaaza­[16]­paracyclophane), decorated with six lateral amide functions, is synthesized by a convergent and modular strategy. This macrocycle is shown to undergo supramolecular polymerization in o-dichlorobenzene, and its nanotubular structure is elucidated by a combination of spectroscopy and microscopy techniques, together with X-ray scattering and molecular modeling. Upon sequential oxidation, a spectroelectrochemical analysis of the supramolecular polymer suggests an extended electronic delocalization of charge carriers both within the macrocycles (through bond) and between the macrocycles along the stacking direction (through space).