Zigzag on a zigzag: Trap of hydrogen-bonded water molecules in a luminescent metal-organic network

A four-connected 2-D metal-organic coordination polymer {[Cd(mpdc)(phen)] · H₂O}(mpdc = 2,6-dimethylpyridine-3,5-dicarboxylate, phen = 1,10-phenanthroline) has been assemblied from cadmium ions and two kinds of organic ligands under hydrothermal conditions, characterized by single-crystal X-ray diffraction analysis. The 2-D metal-organic network was constructed from binuclear [Cd(O₅N₂)]₂ clusters bridged by mpdc^2- ligands. The most interesting is that water molecules trapped by the 2-D network look as if its motif is projected from the zigzag arrangement of cadmium atoms in the 2-D network via hydrogen bonding interactions. In addition, new compound exhibits strong luminescence at λ_max = 525 nm upon excitation at 367 nm.