Thermotropic Liquid-Crystalline Behavior of Some Single- and Double-Chained Pyridinium Amphiphiles

Article abstract of DOI:10.1021/j100207a035

The present study describes the thermotropic phase transitions in several structurally related amphiphiles containing pyridinium head groups.From the combined results of differential scanning calorimetry (DSC), optical polarization microscopy, and X-ray diffraction, the thermotropic liquid-crystalline phases in present 1-3 and 10 have been charactarized.For amphiphiles 1 and 10 a smectic-A phase was observed.The thermotropic liquid-crystalline state of 2 could be identified as a smectic-C phase.The tilt angle of the director was calculated to be ca. 58 deg.The X-ray diffraction pattern of the mesophase of 3 could be best rationalized terms of a smectic-H phase.The cell constants of the monoclinic lattice are a=8.63 Angstroem, b=4.79 Angstroem, c=51.8 Angstroem, and β=132.6 deg, with two molecules per unit cell.The results are discussed in relation to the calculated molecular dimensions obtained from space-filling molecular models.Probable arrangements of the organized amphiphiles in the particular smectic phase are proposed.