Extending Primary Ammonium Dicarboxylate (PAD) to Diprimary Ammonium Dicarboxylate (DPAD) synthon and its implication in supramolecular gelation

Abstract

A series of organic salts derived from various dicarboxylic acids and two α,ω-diamines, namely, 1,3-diaminopropane and 1,4-diaminobutane, were prepared and characterized by various physicochemical techniques, including single-crystal X-ray diffraction, with the aim of extending the well-studied 2D primary ammonium dicarboxylate (PAD) supramolecular synthon in the context of supramolecular gelation. Single crystal structures of 9 out of 14 diprimary ammonium dicarboxylate (DPAD) salts were determined. The results showed that none of the salts displayed the expected 2D DPAD synthon; instead, all of them self-assembled into a 3D hydrogen-bonded network. Consequently, only two salts, namely, B₃FA and B₄SA, appeared to show gelation behavior producing weak gels—a finding that corroborated well with the current understanding of gelation.