Heterometallic, Hybrid, Heavy Main-Group Iodometallates Containing Lanthanide Complexes: Template Synthesis, Structures, Thermal, Optical, Luminescent and Magnetic Properties
Résumé
Using [Ln(L)8]3+ [Ln = Tb, Y; L = dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF)] cations as templating reagents, the syntheses and crystal structures of the following new metal organicinorganic hybrid complexes based on either discrete clusters or 1D chains of an iodoplumbate or-bismuthate moiety are reported: [Tb(DMSO)8]2[(DMSO)2Pb5I16] (1), [Tb(DMF)(8)][Pb3I9](1)(infinity)center dot DMF (2) and [Ln(DMF)8][Bi2I9] [Ln = Y (3), Tb (4)]. These derivatives were characterized by thermogravimetric analysis (TGA), diffuse-reflectance spectroscopy, luminescence spectroscopy and magnetic studies. TGA studies show that the thermal stability of these complexes decreases in the order 2 > 3 similar to 4 > 1. An optical band-gap in the range 1.902.15 eV in the diffuse-reflectance spectra of 14 indicate their potential use as semiconductors, 3 and 4 being the most promising because of their low band gap values. Compared to the precursors [Tb(DMSO)8]I3 and [Tb(DMF)8]I3, the high energy transitions in the excitation spectra of 1, 2 and 4 are quenched by a process that is best attributed to the autoionization of the carriers in the material. The temperature dependence of the magnetic susceptibilities of 1, 2 and 4 was reproduced well by a CurieWeiss plot at 2-300 K.