IntroductionCrystal engineering of coordination polymers constructedviaa net­based approach has been a successful synthetic route to new framework structures.1The deliberate selection of organic building blocks as well as metal centers, based on their geometric preference and different functionality, is the essential step of this strategy and has produced many fascinating metal–organic polymers.2The construction of extended metal–organic structures based on bifunctional organic ligands is very attractive since it utilizes both the covalently­bonded metal–ligand and hydrogen­bonded ligand–ligand properties, and the ligand functionality is retained in the network structures.3The incorporation of hydrogen bonding into crystal structures may have interesting applications. For example, metal complexes with hydrogen bonding capabilities may be used to generate metal–organicnanofibers,4aand also for use as chemotherapeutic reagents.4b2,2′­Dipyridylamine is a flexible ligand with bifunctionality, capable of forming both covalent- and hydrogen-bonds,5and other interesting properties.6While the bifunctionality of flexible 2,2′­dipyridylamine has been well utilized by mixing with rigid organic building blocks, such as oxalate, in order to construct two­dimensional frameworks,5mixing of the flexible unit with carbonate–metal chain structures has been less well studied. Carbonate anions are simple inorganic units with tridentate capability and have been widely used as bridges or counter­anions in network complexes.7Pure carbonate–metal extended inorganic chain structures may therefore be reasonably expected (seeScheme 1).7The carbonates are good candidates for hydrogen bonding with bifunctional organic ligands in the network structures, and the inorganic chain inScheme 1can be expected to be linked by bifunctional 2,2′­dipyridylamine with both covalent and hydrogen bonds to form a two­dimensional metal–organic polymer. Here, we report a novel metal–organic polymeric structure with alternating one­dimensional serpentine ribbon chains and two­dimensional layer networks in [Cu(DPA)CO3]·3H2O1(DPA⊕=⊕2,2′­dipyridylamine).View of the carbonate–metal chain.