Mesomorphic complexes through hydrogen bonding between alkoxy‐substituted triarylmelamines and semiperfluorinated benzoic acids

Abstract

The thermal behaviour of two 2,4,6‐triarylamino‐1,3,5‐triazines carrying either three or six peripheral alkoxy chains have been investigated in binary mixtures with two‐chain and three‐ chain partially fluorinated benzoic acids by means of polarizing microscopy, differential scanning calorimetry and X‐ray scattering. The melamines form hydrogen‐bonded aggregates with the complementary carboxylic acids. Each investigated equimolar mixture exhibits a hexagonal columnar mesophase. In the case of the six‐fold alkoxy‐modified triazine the individual columns are built up by descrete hetero‐dimers with a circular cross‐sectional shape. The segregation of fluorinated from lipophilic side chain regions leads to a superstructure within the hexagonal lattice. The hexagonal columnar phases of 1:1 compositions of the triazine, incorporating just three aliphatic chains with the semiperfluorinated benzoic acids, are formed by pairs of H‐bonded dimeric supermolecules.

Acknowledgement

This work was supported by the Land Brandenburg, Germany, and the Fonds der Chemischen Industrie. The authors are very grateful to B. Smarsly for kind support in performing X‐ray measurements at the Max Planck Institute of Colloids and Interfaces, Potsdam‐Golm, Germany.