Effect of chirality on the structural behaviour of hydrogen-bonded n-alkylammonium pyroglutamates in the crystalline and smectic state.

A set of optically active and racemic n-alkylammonium pyroglutamates from dodecyl to octadecyl were synthesized and characterised. Their thermotropic polymorphism was investigated by polarizing optical microscopy, differential scanning calorimetry and dilatometry. Their structure in the crystalline and smectic state was analysed by X-ray diffraction. The hydrogen bonding of the molecules in the crystalline and smectic layers was examined by infrared spectroscopy. The chirality control over the supramolecular self-assembly of the molecules along with the homochiral and heterochiral architecture of the self-assembled dimers are briefly discussed.