Redox-Driven Molecular Switches Consisting of Bis(benzodithiolyl)bithienyl Scaffold and Mesogenic Moieties: Synthesis and Complexes with Liquid Crystalline Polymer

Molecular switches composed of a
benzodithiolylbithienyl scaffold
and biphenyl or terphenyl mesogenic substituents were designed and
synthesized. The molecular switches could undergo redox-triggered
interconversion between the cationic form and cyclized neutral form,
and this was confirmed using cyclic voltammetry and UV–vis
spectroscopy. Binary complexes consisting of the molecular switches
and a liquid crystalline polymer (LCP) were prepared to investigate
the function of these redox-active molecular switches as actuating
dopants. X-ray diffraction measurements were performed to determine
the differences between the layer spacings of the complexes in the
liquid crystalline phase with the oxidized and reduced states of the
molecular switches. The LCP that was doped with the oxidized cationic
form of the molecular switch had layer spacings that were up to 4%
larger than the layer spacings in the polymer that was doped with
the reduced cyclized molecular switch. Our approach will allow stimulus-responsive
deformable materials to be constructed and give an impetus for fabricating
redox-driven soft actuators.