In this paper, we have synthesized two new coordination complexes and two coordination polymers at room temperature formulated as}(Htata)2[Cu(pydco)2(tata)]·3H2O{ (1), {(H9a-acr)2·[Ni0.51Zn0.49(pydco)2(H2O)2]·4H2O} (2),] Cu(pydco)(H2O)2[n (3), [Ag(Hpydco)(2a-pym)]n (4) in which pydco = pyridine-2,6-dicarboxylic acid N-oxide, tata = 2,4,6-triamino-1,3,5-triazine (melamine), 9a-acr = 9-aminoacridine and 2a-pym = 2-aminopyrimidine. The structures of these compounds and their physical and chemical properties were characterized via elemental analysis, infrared spectroscopy and single crystal X-ray diffraction methods. Complex 1 has a honeycomb-like 2-D network whilst complex 2 is a mixed crystal with almost equal amounts of Ni and Zn in the metal sites and has a 4-connected {4^4.6^2}topology. Complexes 3 and 4 display coordination modes for the pydco ligand which differ from those of previous reports. Complex 3 forms a 1-D 3-connected staircase-like network with unequal footsteps and possess a {4^2.6} topology while 4 is a 2-D staircase-like 4-connected network with a {4^4.6^2} topology exhibiting rectangular grids Ag─Ag interactions. In the structures of 1–4 several supramolecular interactions like hydrogen-bonding and π···π and lone pair···π stacking interactions play important roles in the formation and stability of the crystalline materials. The complexation reactions of these systems with Cu2+ and Ag+ ions were investigated by potentiometric pH titration method (solution studies). The stoichiometry of the most abundant species in the solution was very similar to the corresponding crystalline metal ion complexes.

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