A novel two‐dimensional metal–organic supramolecular framework including π–π stacking and hydrogen‐bond interactions

[μ‐N,N′‐Bis(pyridin‐3‐yl)benzene‐1,4‐dicarboxamide‐1:2κ²N:N′]bis{[N,N′‐bis(pyridin‐3‐yl)benzene‐1,4‐dicarboxamide‐κN]diiodidomercury(II)}, [Hg₂I₄(C₁₈H₁₄N₄O₂)₃], is an S‐shaped dinuclear molecule, composed of two HgI₂ units and three N,N′‐bis(pyridin‐3‐yl)benzene‐1,4‐dicarboxamide (L) ligands. The central L ligand is centrosymmetric and coordinated to two Hg^II cations via two pyridine N atoms, in a syn–syn conformation. The two terminal L ligands are monodentate, with one uncoordinated pyridine N atom, and each adopts a syn–anti conformation. The HgI₂ units show highly distorted tetrahedral (sawhorse) geometry, as the Hg^II centres lie only 0.34 (2) or 0.32 (2) Å from the planes defined by the I and pyridine N atoms. Supramolecular interactions, thermal stability and solid‐state luminescence properties were also measured.