ION-PAIR AMPHIPHILES FROM SODIUM DODECYL-SULFATE AND AMMONIUM AMPHIPHILES CARRYING FUNCTIONALIZED AZOBENZENE UNITS

New ammonium amphiphiles having a N,N-dimethyl-N-hydroxyethylammonium headgroup and various azobenzene mesogenic units connected by a decyl or dodecyl spacer have been synthesized. The azobenzene unit is functi onalized at the 4-position with a cyano, methoxy or fluoro substituent . For the cyano-substituted amphotropes and the fluoro compound with a dodecyl spacer a smectic phase is formed as was observed by different ial scanning calorimetry and polarization microscopy. Complexation wit h sodium dodecyl sulfate, SDS, in a 1:1 molar ratio induces the format ion of a smectic phase for the compounds with a decyl spacer. The comp ounds with a dodecyl spacer showed rather complex behavior attributed to different crystal morphologies. The ammonium amphotropes form aggre gates in water when heated above their Krafft temperature. However, th ese aggregates are not stable and crystallize upon cooling. The ion pa ir amphiphiles with SDS as second component form vesicles in water as observed by optical and electron microscopy. The observed blue shift i n the UV absorption maximum of the amphotropes upon addition of SDS in dicates pi-pi stacking between mesogenic units resulting from aggregat ion.