SOME NOVEL CHOLESTERIC LIQUID-CRYSTALS

A novel series of cholesteric liquid crystals (CN-r(n)) made by quaternization of the new mesogenic unit cholesteryl isonicotinate (CN) with n-alkyl salts, CnH2n+1 (T) (n = 2 to 8, T = 4-MeC6H4SO3) has been prepared. Differential scanning calorimetry and polarizing optical microscopy studies reveal that all of these salts exhibit an enantiotropic cholesteric phase but for the cholesteryl isonicotinate unit the cholesteric phase is monotropic. For all members of the series the cholesteric-isotropic transitions are not reversible as these salts begin to decompose before their cholesteric-isotropic transition point is reached.