Origin of the Difference in Phase Transition Behavior between TwoType of All-Organic Radical Liquid Crystals
We have synthesized two types of all-organic radical liquid crystalline (LC) compounds, trans-2-alkoxyphenyl-5-[4-(4-alkoxybenzenecarbonyloxy)phenyl]-2,5-dimethylpyrrolidine-1-oxy (1) and 4-alkoxyphenyl trans-4-[5-(4-alkoxyphenyl)-2,5-dimethylpyrrolidine-1-oxy-2-yl]benzoate (2) and have fully characterized their LC properties. Although the only difference in the molecular structure between 1 and 2 is the orientation of a binding group connecting the core portion and one side-chain (-OCO- and -COO- for 1 and 2), the racemic or enantiomerically enriched 2 showed an SmA phase, or SmA* and TGBA* phases, which were not observed for 1, besides N and SmC, or N* and SmC* phases, respectively. Here we discuss the origin of these differences on the basis of their crystal structures determined by X-ray crystallographic analysis.
Pietro VINCENZINI and Giancarlo RIGHINI
Y. Uchida et al., "Origin of the Difference in Phase Transition Behavior between TwoType of All-Organic Radical Liquid Crystals", Advances in Science and Technology, Vol. 55, pp. 42-45, 2008