Helical polyacetylene synthesized under chiral nematic liquid crystals

Abstract

We synthesized helical polyacetylene films under asymmetric and anisotropic reaction field consisting of chiral nematic (N *) liquid crystals. A series of axially chiral binaphthols and chiral phenylcyclohexyl derivatives were used as chiral dopants to induce N * liquid crystals. Acetylene polymerizations were carried out with Ti(O- n-Bu) 4-Et 3Al under N * reaction field. Measurements of SEM and CD spectra showed that the polyacetylene films are composed of clockwise or counter-clockwise helical structures not only in fibril but also in each polyene chain. By virtue of its high electrical conductivity of 1.51.8 x 103 S/cm after iodine doping, the helical polyacetylene might serve as a molecular solenoid based on conducting polymer. The helicity of the present film also suggests a feasibility of second-order nonlinear optical material.