Reduced Schiff bases with a common p-nitro-o-phenylenediamine moiety have been synthesised and their structures have been characterized by single-crystal structural analysis. Schiff bases having self-complementary H-bond donors and H-bond acceptors can form a “scissors” like structure through intermolecular H-bonding interaction. Reduced Schiff bases interact with biologically important dihydrogenphosphate ion and form stable complexes. Furthermore, dihydrogenphosphate and water form an unprecedented self-assembled dihydrogenphosphate–water [H₂PO₄·H₂O]_nⁿ⁻ 1D supramolecular polymer upon complexation with reduced Schiff bases.