Elaboration of Luminescent and Magnetic Hybrid Networks Based on Lanthanide Ions and Imidazolium Dicarboxylate Salts: Influence of the Synthesis Conditions

The syntheses and characterization of four new hybrid coordination networks based on lanthanide ions (Ln = Nd, Sm) and 1,3-carboxymethylimidazolium (L) salt in the presence of oxalic acid (H2ox) are reported. The influence of the synthesis parameters, such as the nature of the lanthanide ion (Nd3+ or Sm3+), the nature of the imidazolium source (chloride [H2L][Cl] or zwitterionic [HL] form) and the presence or not of oxalic acid (H2ox), is discussed. In the presence of oxalic acid, the samarium salt gives only one compound [Sm(L)(ox)(H2O)]·H2O, whatever the nature of the imidazolium ligand, while the neodymium salt leads to three different compounds, [Nd(L)(ox)(H2O)]·H2O, [Nd(L)(ox)0.5(H2O)2][Cl] or [Nd2(L)2(ox)(NO3)(H2O)3][NO3], depending on the imidazolium ligand. In the absence of oxalic acid, gels are obtained, except for the reaction between the neodymium salt and [H2L][Cl], which leads to [Nd(L)(ox)(H2O)]·H2O. All compounds crystallized and their structures were determined by single crystal diffraction. The description of these new phases was consistently supported by ancillary techniques, such as powder X-ray diffraction, thermal analyses and UV-visible-near infrared spectroscopy. The luminescent and magnetic properties of the three pure compounds [Sm(L)(ox)(H2O)]·H2O, [Nd(L)(ox)(H2O)]·H2O and [Nd2(L)2(ox)(NO3)(H2O)3][NO3] were also studied.