A Cu(II)-malonate complex with formula {(C5H6N2Cl)(12)[Cu(1)(C3H2O4)(2)][Cu(2)(C3H2O4)(2)(H2O)(2)][Cu(4)(C3H2O4)(2)[Cu(3)(C3H2O4)(2)(H2O)(2)] (ClO4)(4)}(n) (1) [C5H6N2Cl = protonated 2-amino-S-chloropyridine, C3H4O4 = malonic acid, ClO4- = perchlorate] has been synthesized from purely aqueous media simple by mixing the reactants in their stoichiometric ratio, and its crystal structure has been determined by single-crystal X-ray diffraction. In 1, copper(II) malonate units form infinite ID polymeric chains, which are interlinked by hydrogen bonds to generate 2D sheets. These 2D sheets are joined side by side primarily by various hydrogen bonds to form a 3D structure. A multitude of salt bridges are formed in this structure, connecting the protonated 2-amino-5-chloropyridines and the malonate ligands of the polymeric polyanion. Examining this characteristic of the solid-state architecture, we noticed several salt-bridge (sb)center dot center dot center dot pi interactions and an unexplored interaction between the lone pair (lp) of one malonate oxygen atom and a planar salt bridge. The combination of this interaction with various other weak intermolecular forces results in a remarkably extended supramolecular network combining a wide variety of interactions involving pi-systems (Cl center dot center dot center dot pi, pi center dot center dot center dot pi) and salt bridges (sb center dot center dot center dot pi and lp center dot center dot center dot sb). We describe the energetic and geometric features of this lone pair-salt-bridge interaction and explore its impact on the resultant supramolecular organization using theoretical DFT-D3 calculations.