A series of group 12 metal complexes, [ZnCl₂L₂]·H₂O (1), [ZnBr₂L₂]·0.75EtOH (2a), [ZnBr₂L₂]·0.8H₂O (2b), [ZnI₂L₂] (3), [HgCl₂L₂] (4), [HgBr₂L₂] (5), and [HgI₂L] (6), have been synthesized from a naphthyl-substituted pyridylurea ligand N-(1-naphthyl)-N′-(3-pyridyl)urea (L) and zinc(II) or mercury(II) halides. In the zinc(II) dichloro complex, 1, the chloride ions participate not only in metal coordination but also in N–HCl hydrogen bonding with the urea NH groups, giving an overall layered structure. In contrast, the coordinated bromide and iodide anions in 2 and 3 are not involved in hydrogen bonding; instead, the urea groups undergo self-association to form nano-tubular structures with various pore sizes stacked by the semi-macrocyclic [ZnX₂L₂] synthons. Most interestingly, although different solvent molecules [EtOH (2a) and H₂O (2b)] can be encapsulated in the nano-tubular zinc dibromo complexes, a competitive experiment conducted in the EtOH/H₂O mixed solvents showed that the nanotube can selectively capture the EtOH molecule, as confirmed by X-ray single-crystal diffraction and solid-state fluorescence studies. With the tetrahedral mercury(II) ion, complexes 4 and 5 are isomorphous 2D sheet structures held by N–HO hydrogen bonds and π–π stacking interactions. The 2D sheets are further linked by C–HCl/Br weak interactions into a hydrogen-bonded 3D framework. Notably, compound 6 contains an uncommon trigonal-planar Hg^II center and forms a 1D chain structure via the typical ureaurea hydrogen bonding and π–π stacking interactions of L, which further aggregates to a 2D parallelogram grid framework through C–HI weak interactions. The solid-state fluorescent properties of L and the complexes 1–6 have also been investigated at room temperature.