| Liquid crystal lactic acid derivatives can exhibit various liquid crystal phases However,there are only few reports on their self-assembly behavior in solvents.The liquid crystalline and self-assembly behaviors of some bicyclic and tricyclic liquid crystals derived from lactic acid has been reported by us.Moreover,the self-assembly behavior of some lipodipeptides has been reported by us.A "C-terminal determination" rule was found.The handedness of the organic self-assembly depends on the chirality of the C-terminal amino acid residue.Herein,the liquid crystalline and self-assembly behaviors of liquid crystals containing two lactic acid residues were studied.We want to know which chiral residue plays an important role in the liquid crystalline behaviors and the handedness of the organic self-assemblies formed in organic solvents.The results are as following:Firstly,the mesomorphic properties of four compounds containing two lactic acid residues and a perfluorocarbon chain were studied.The optical activity of these liquid crystals is mainly determined by the chirality of the lactic acid residue near the liquid crystal core,and the chirality plays an important role in the arrangement of molecules in the liquid crystal phase.Secondly,dilactic acid derivatives with different fluorocarbon and alkyl chains were synthesized.Compounds with different fluorocarbon chains can self-assemble into different nanostructures in organic solvents.When the fluorocarbon chain length is shorter,it seems to be easier to assemble into a helical morphology.For the compounds with same fluorocarbon chain length,with decreasing the alkyl chain length,nanotube is feasible to be formed in organic solvents.With increasing the alkyl chain length,a twisted nanostructure is feasible to be formed.Lastly,two series of compounds with a lactic acid residue and a semi-perfluorocarbon chain were synthesized.The fluorocarbon chain and alkyl chain lengths of the compounds show different effects on the liquid crystalline behavior.With increasing the fluorocarbon chain length,the clearing point and thermostability of SmC*phase are increased.With increasing the alkyl chain length,the SmB phase is suppressed and the SmC*phase appears.Comparison of compounds with-CF3,-CHF2 and-CF2Cl groups at the terminals of the fluorocarbon chains,the clearing point and melting point sequences are also different,the compounds with semi-perfluorocarbon chains show the widest liquid crystalline temperature range. |
