One-, Two-, and Three-Dimensional Arrays of Eu³⁺-4,4,5,5,5-pentafluoro-1-(naphthalen-2-yl)pentane-1,3-dione complexes: Synthesis, Crystal Structure and Photophysical Properties

A novel β-diketone, 4,4,5,5,5-pentafluoro-1-(naphthalen-2-yl)pentane-1,3-dione (HPFNP), which contains polyfluorinated alkyl group, as well as the long conjugated naphthyl group, has been used for the synthesis of a series of new tris(β-diketonate)europium(III) complexes of the general formula Eu(PFNP)3·L [where L = H2O, 2,2′-bipyridine (bpy), 1,10-phenanthroline (phen), 4,7-diphenyl-1,10-phenanthroline (bath)] and characterized by various spectroscopic techniques. The single-crystal X-ray diffraction analysis of Eu(PFNP)3.bpy revealed that the complex is mononuclear, the central Eu3+ ion is coordinated by six oxygen atoms furnished by three β-diketonate ligands, and two nitrogen atoms from a bidentate bipyridyl ligand, in an overall distorted square prismatic geometry. Further, analysis of the X-ray crystal data of the above complex also revealed interesting 1D, 2D, and 3D networks based on intra- and intermolecular hydrogen bonds. The room-temperature PL spectra of the complexes are composed of typical Eu3+ red emissions, assigned to transitions between the first excited state (5D0) and the multiplet (7F0−4). The results demonstrate that the substitution of solvent molecules by bidentate nitrogen ligands in Eu(PFNP)3·H2O·EtOH greatly enhances the quantum yields and lifetime values.