Abstract:
We report on the synthesis and characterization of
multifunctional ionic liquid crystals (melting points below 100
°C) which possess chirality and fluorescent behavior as well as
mesomorphic and magnetic properties. In this regard, (1R,2S)-
(−)-N-methylephedrine ((−)MeEph), containing a chiral center,
is linked with variable alkyl chain lengths (e.g., 14, 16, and 18
carbons) to yield liquid crystalline properties in the cations of
these compounds. A complex counteranion consisting of trivalent
dysprosium (Dy3+) and thiocyanate ligand (SCN−) is employed,
where Dy3+ provides fluorescent and magnetic properties.
Examination of differential scanning calorimetry (DSC) and
hot-stage polarizing optical microscopy (POM) data confirmed
liquid crystalline characteristics in these materials. We further
report on phase transitions from solid to liquid crystal states,
followed by isotropic liquid states with increasing temperature. These compounds exhibited two characteristic emission peaks in
acetonitrile solution and the solid state when excited at λex = 366 nm, which are attributed to transitions from 4F9/2 to 6H15/2 and
4F9/2 to 6H13/2. The emission intensities of these compounds were found to be very sensitive to the phase.
