Preparation, crystal structure and luminescent properties of the (6,3) type network supramolecular lanthanide picrate complexes with 2,2′-[(1,2-naphthalene)bis(oxy)]bis[N-(phenylmethyl)]acetamide

Solid complexes of lanthanide picrates with a new podand-type ligand, 2,2′-[(1,2-naphthalene)bis(oxy)]bis[N-(phenylmethyl)]acetamide (L) have been prepared and characterized by elemental analysis, conductivity measurements, IR and electronic spectroscopies. The crystal and molecular structures of the coordination polymer {[Eu2L3(Pic)6]·(CHCl3)3·(H2O)0.5}n have been determined by single-crystal X-ray diffraction, and the structure displays a two-dimensional honeycomb-like framework in the ab plane, which can be regarded as a (6,3) topological network with europium atoms acting as “three-connected” centers. Furthermore, the coordination layers are linked by the intermolecular hydrogen bonds to form a three-dimensional (3-D) netlike supermolecule. Under excitation, Eu complex exhibited characteristic emissions. The lowest triplet state energy level of the ligand indicates that the triplet state energy level of the ligand matches better to the resonance level of Eu(III) than Tb(III) ion.