A new heterometallic two-dimensional coordination polymer, {[NiNa(H-EDTA)(H2O)]·H2O}n, has been synthesized and structurally and physicochemically characterized to establish correlations between its structural features and functional properties. Single-crystal X-ray diffraction reveals the formation of a layered coordination framework constructed from μ2-bridging mono-protonated EDTA ligands that link Ni(II) and Na(I) centres. The Ni(II) ion adopts a slightly distorted octahedral geometry, whereas the Na(I) centre exhibits a flexible coordination environment, enabling the formation of an extended two-dimensional network. Hirshfeld surface analysis indicates that H \(\cdots\) O/O \(\cdots\) H interactions (48.9%) dominate the intermolecular contacts, with support from van der Waals interactions and secondary Na \(\cdots\) O contacts, which collectively stabilize the layered supramolecular arrangement. FT-IR and UV–Vis spectroscopy confirm the coordination mode of the ligand and the octahedral environment of the Ni(II) centre. Thermal analysis reveals a multistep decomposition process with good agreement between experimental and calculated weight losses. Nitrogen adsorption–desorption measurements exhibit a type IV isotherm with H3 hysteresis, consistent with a layered structure with interparticle mesoporosity, and a BET surface area of 22.06 m2/g. The antibacterial activity of the coordination polymer was evaluated against representative Gram-positive and Gram-negative bacteria, showing significantly enhanced inhibition compared to free EDTA and Ni(CH3COO)2, highlighting the effect of coordination-driven structural organization. These findings demonstrate that the interplay between rigid and flexible coordination environments plays a decisive role in determining the structural stability and multifunctional properties of the material.
