The title complex Cu₄(dhbd)₂(dpphen)₄•2H₂O]•8H₂O(H4dhbd＝2,3-dihydroxybutanedioic acid, dpphen＝4,7-diphenyl-1,10-phenanthroline) has been hydrothermally synthesized and characterized by means of single crystal X-ray diffraction, elemental analysis, IR and TGA analysis. Crystal structural analysis reveals that, because water molecules bond to Cu(II) atoms, the dhbd ligand can only adopt a hydroxyl oxygen atom to bridge two reversed U-shaped subunits into a novel centrosymmetric dual-U-shaped tetranuclear Cu(II) structure. Each U-shaped frame consists of two crystallographically distinct Cu(II) atoms, two dpphen ligands and one coordinated water molecule. Through cyclic hydrogen bonding with motif formed by coordinated water molecules and coordinated hydroxyl groups of dhbd from adjacent tetranuclear units, these adjacent neighbors are connected to afford a 1D supramolecular chain along axis a, which is further extended via aromatic intercalations and other crystallization water molecules into a 3D structure with channels. The binding mode of dhbd group was not observed so far. Variable-temperature magnetic susceptibility measurements indicate the presence of weak antiferromagnetic interactions.

Key words: 2,3-dihydroxybutanedioic acid, copper(II) complex, bonding mode, crystal structure, magnetic property