Synthesis, crystal structure and fluorescence emission of complexes of lanthanide picrates with N,N′-dimethyl-N,N′-diphenyl-3,6-dioxaoctanediamide

Lanthanide picrate complexes with the ligand N,N'-dimethyl-N,N'-diphenyl-3,6-dioxaoctane- diamide (DDD) [Ln(Pic)(3)(DDD)] (Ln = La, Pr, Sm, Eu, Er, Y) have been prepared in non-aqueous medium and characterized by elemental analysis, conductivity measurements, IR, and H-1 NMR spectra. The Sm(III) complex [Sm(Pic)(3)(DDD)] . 1/2H(2)O is triclinic, space group P1, with a = 12.421(1) Angstrom, b = 13.081(2) Angstrom, c = 14.609(1) Angstrom, alpha = 82.61(1)degrees, beta = 86.67(1)degrees, gamma = 86.83(1)degrees, U = 2347.2(4) Angstrom(3), D-c = 1.698 g.cm(-3) for Z = 2. The structure was refined to R = 0.035 based on 8727 observed reflections. The results reveal that DDD forms a ring-like structure with its four O atoms coordinating to the metal ions as a multidentate ligand, together with one O atom of the bidentate picrate. The Eu(III) complex shows strong emission when excited with 433 nm radiation in the solid state. The intensity ratio value eta(D-5(0) --> F-7(2)/D-5(0) --> F-7(1)) is 16.8.