Secondary Ammonium Dicarboxylate (SAD)A Supramolecular Synthon in Designing Low Molecular Weight Gelators Derived from Azo-Dicarboxylates

The supramolecular synthon namely secondary ammonium dicarboxylate (SAD) synthon has been exploited to design a new series of low molecular weight gelators (LMWGs) derived from azobenzene-4,4′-dicarboxylic acid and azobenzene-4,4′-diacrylic acid, and various secondary amines. Single crystal structures of six such salts exclusively established the presence of SAD synthon. Two such salts namely, dicyclohexylammonium azobenzene-4,4′-diacrylate (2.DCHA) and dihexylammonium azobenzene-4,4′-diacrylate (2.DHA) displayed intriguing gelation properties. Powder X-ray diffraction in combination with single crystal X-ray data established existence of SAD synthon in the structure of the gel network of 2.DCHA. UV-irradiation of the salts as well as the gel did not show any trans–cis isomerization of the azo-moiety.