Four new framework solids consisting of coordination polymers [Cd₂(L)(H₂O)₂(DMA)]_n (1), [Cu₂(L)(H₂O)₂]_n (2), [Co₂(L)(H₂O)₅]_n (3) and [Mn₂(L)(H₂O)₅]_n (4) (H₄L = 5-(3,5-dicarboxybenzyloxy)isophthalic acid; DMA = dimethyl acetamide) have been synthesized under hydro(solvo)thermal conditions and characterized by X-ray crystallography. In all cases, the metal-ion connectors consist of di-nuclear clusters. The fully de-protonated flexible tetradentate organic linker assumes a flat conformation with laterally oriented carboxylate functions in 1 and 2, but a twisted conformation with one carboxyphenyl residue rotated by nearly 90° with respect to the other in the isomorphous structures of 3 and 4. The resulting polymeric metal–organic lattices in 1 and 2 are perforated by wide (accounting for more than 50% of the crystal volume) solvent-accessible channel voids. In 3 and 4 the organic linker is characterized by tetrahedral tetra-carboxylate functionality, inducing the formation of open polymeric architectures with diamondoid geometries which interweave into one another in the crystal to fill most of the empty space. The remaining voids are filled by molecules of water. Thermal analysis (TGA and DTA) features of 1–4, nitrogen gas sorption behavior of 2 and solid-state variable temperature magnetic susceptibility data of 3 and 4 are reported as well.