Heterometallic, hybrid, heavy main-group iodometallates containing lanthanide complexes: Template synthesis, structures, thermal, optical, luminescent and magnetic properties

摘要

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 organic-inorganic hybrid complexes based on either discrete clusters or 1D chains of an iodoplumbate or-bismuthate moiety are reported: [Tb(DMSO) _8] _2[(DMSO) _2Pb _5I _(16)] (1), [Tb(DMF) _8][Pb _3I _9] 1∞·DMF (2) and [Ln(DMF) _8][Bi _2I _9] [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 ≈ 4 > 1. An optical band-gap in the range 1.90-2.15 eV in the diffuse-reflectance spectra of 1-4 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]I _3 and [Tb(DMF) _8]I _3, 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 Curie-Weiss plot at 2-300 K.