Supramolecular chirality of columnar mesophases consisting of H-bonded complexes of melamine and polycatenar benzoic acids

Abstract

The present work describes a series of H-bonded complexes consisting of a melamine derivative and polycatenar acids that show columnar liquid crystalline behaviour. Chirality has been transferred from the molecular blocks (either the acids, A3* and A4*, or the melamine, T2*) to the columnar organization. Particular effort and attention has been paid to structural characterization by NMR techniques [1D NMR spectroscopy and diffusion-ordered spectroscopy (DOSY) experiments] of the complexes in solution. The mesomorphic arrangements of all the complexes have been studied by polarizing optical microscopy (POM), differential scanning microscopy (DSC) and powder X-ray diffraction. The chiral nature of the supramolecular organization in the mesophase has been confirmed by circular dichroism spectroscopy on neat samples over a range of temperatures.