Pitch measurements in chiral lyotropic chromonic liquid crystals

The recent interest in lyotropic chromonic liquid crystals (LCLCs) has resulted in significant understanding of the assembly behaviour and liquid crystal properties of these water-based systems. On the other hand, there has been much less investigation into chiral LCLCs, which result if the chromonic molecule is chiral or if a chiral dopant is added to the solution. Measurements of the pitch of the LCLC disodium cromoglycate (DSCG) with several chiral dopants using both the Cano wedge and fingerprint texture methods are reported. The results include quantitative measurements of both the pitch and the helical twisting power. The ability of dopants to induce twist in DSCG varies widely, with some having almost no effect, with others producing a pitch approaching 3 mu m and with most displaying an inverse pitch-dopant concentration dependence that is nonlinear at high concentrations. [GRAPHICS] .