This work investigates the supramolecular aggregation of Cu(II) complexes based on a combination of the heterocyclic N-donor ligand 2-aminopyrimidine (2-apym) and a variety of different carboxylate ligands, like salicylic acid (H2SAL), maleic acid (H2MAL), and glycine (HGLY). Four new Cu(II) complexes [Cu(HSAL)2(2-apym)2](I), [Cu(HSAL)2(2-apym)2]? (H2SAL)2(2-apym) (I\'), {(H2-apym)[Cu(GLY)(m-Cl)2Cl]}n (II) and [Cu(m-MAL)(2-apym)]n (III) have been synthesized and characterized by elemental analyses, FT-IR spectra, and X-ray structural analyses. I and I9 appear as molecular clusters whereas II is a 1-D coordination polymer with weak axial Cu–Cl interactions. However the last one shows a 2-D coordination polymer with trigonal bipyramidal geometry for Cu(II) ion. The two last cases have no molecular fragments packed with non-covalent interactions. In these new supramolecular compounds, existent species join together with the cooperation of multiple inter/intra-molecular classical O–H…O/N, N–H…O/N, and non-classical N–H…Cl hydrogen bonds (H-bonds), offset face to face p…p, edge to face C/N–H…p, and lp…p stacking interactions in the form of various homo/hetero-synthons leading to architecturally different structures. DFT calculations were used to estimate the binding energy of the involved non-covalent interactions and whole stabilization energy of related network of I, I9, and II. Theoretical calculations facilitate the comparison of intermolecular interactions, which demonstrate that for all of I–II, N–H…N and N– H…O H-bonds govern the network formation. The equilibrium constants for the three proton-transfer systems including SAL/2-apym, GLY/2-apym, MAL/2-apym, the stoichiometry and stability of complexation of these systems with Cu2+ ion in aqueous solution were investigated by potentiometric pH titration method. The stoichiometries of the most complex species in solution was compared to the crystalline Cu2+ ion complexes with the cited proton-transfer systems.

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