Molecular orientation of hydrogen-bonded liquid crystal (6BA)2-(BPy) x as Studied by 2H NMR

Abstract

The thermal properties of hydrogen-bonded liquid crystal (6BA) 2 -(BPy) x (6BA: 4-n-hexylbenzoicacid, BPy: 4,4'-bipyridine) were investigated by DSC. Two liquid crystal phases (LC I , LC II ) were found for (6BA) 2 -(BPy) 0.5 . In LC II , the distribution of the orientation of molecules was larger than in LC I . The order parameter S of molecular orientation in the liquid crystal phase was estimated from a 2 H NMR spectrum. S decreased rapidly around the LC I -LC II phase transition. The increase in orientational fluctuation of the 6BA dimer with an open dimer structure is predicted to cause the rapid decrease of S.