Crystal structures and fluorescent properties of two linear trinuclear zinc(II) complexes

Two trinuclear zinc(II) complexes, [Zn3(PhCHCHCO2)6 (L)2]H2O (L = 2,2′-bipyridine for 1 and 1,10-phenanthroline for 2), have been synthesized and structurally characterized by single-crystal X-ray diffraction methods. Their crystal structures are featured by the linear arrangement of three zinc atoms linked by six cinnamate anions with the aromatic ligands residing outside. In the crystal structure of 1, the [Zn3(PhCHCHCOO)6(bpy)2] complex molecules are interlinked by C-H⋯O weak hydrogen-bonding interactions into one-dimensional chains parallel to [1 1 0] direction; and in 2, the [Zn3(PhCHCHCOO)6(phen)2] complex molecules are held together by C-H⋯O weak hydrogen-bonding interactions and π-π stacking interactions between the 1,10-phenanthroline groups of neighbouring complex molecules into one-dimensional chains parallel to [1 1 0] direction. Compounds 1 and 2 both exhibit stronger fluorescence compared to that of the free ligands in solid state at room temperature.