Liquid Crystals Composed of N-Acylamino Acids

Optical active N-acyl-L-glutamic acid (L-AGA) exists in two forms distinguishable by differential thermal analysis, infra-red spectroscopy, and X-ray diffraction. The X-ray diffraction patterns suggest that one form is more ordered than the other. As both forms have the same chemical structure and are interchangeable, implying that these are the polymorphic L-AGA, we denote the disordered form L-AGA-A (A: amorphous) and the other more ordered form L-AGA-C (C: crystalline). Data obtained by several methods imply that L-AGA-A is likely to have a parallel order along the long molecular axis with random spaces between the layers. On the other hand, L-AGA-C has a rigid crystalline structure. A new type of cholesteric liquid crystal was obtained by suspending L-LGA-A in specific organic solvents. L-AGA-C did not form any liquid crystalline phases when suspended in the same organic solvents which resulted in liquid crystals from L-AGA-A. The results strongly imply that the particular crystalline structural features are needed to form suspended cholesteric liquid crystalline phases in organic solvents.