Structural diversity and luminescent properties of europium(III) complexes with acrylic acid ligands

Three Europium complexes: [Eu(L1)3(H2O)2]2 (L1 = (E)-3-(2– hydroxyl-phenyl)-acrylic acid) (1), [[Eu(L2)3(H2O)]·H2O (L2 = (E)-3-(3-hydroxyl-phenyl)-acrylic acid) (2), and [[Eu(L3)3(H2O)2] (L3 = (E)-3-(4-hydroxyl-phenyl)-acrylic acid) (3) were synthesized and structurally analyzed by IR, elemental analysis, and the single-crystal X-ray diffraction method. Complex 1 adopts a dinuclear structure, while complexes 2 and 3 are a one-dimensional coordination polymer. The complex 2 possesses a helical H-bonding between the adjacent two chains with homochirality in crystalline solid state. All the complexes form a 3D supramolecular framework by O–H···O hydrogen bonding and π–π interaction in the crystal lattices. The solid photoluminescence of the three complexes has also been investigated at room temperature.