SYNTHESIS, CRYSTAL STRUCTURE AND FLUORESCENCE EMISSION OF COMPLEXES OF LANTHANIDE PICRATES WITH N,N′-DIMETHYL-N,N-DIPHENYL-3,6-DIOXAOCTANEDIAMIDE

Abstract

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 nonaqueous medium and characterized by elemental analysis, conductivity measurements, IR, and ¹H NMR spectra. The Sm(III) complex [Sm(Pic)₃(DDD)] · 1/2 H₂O is triclinic, space group Pl, with a = 12.421(l)Å, b = 13.081(2)Å, c = 14.609(1)Å,α = 82.61(l)°, β = 86.67(1)°, γ = 86.83(1)°, U = 2347.2(4) ų, 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 η(⁵D_o→⁷F2/⁵D_o→⁷F₁) is 16.8.

Key Words:

• Lanthanide picrate
• complex
• X-ray structure
• fluorescence