Structural description, luminescent and magnetic properties of novel 2-D coordination polymers containing thiazolo[5,4-d]thiazole rings and trivalent lanthanide ions

In this work, we have synthesized six coordination polymers [Ln(2)(Thz)(3)center dot 8H(2)O)]center dot 4H(2)O (Ln = La3+, Ce3+, Nd3+, Sm3+, Eu3+, Gd3+; Thz = thiazolo[5,4-d]thiazole-2,5-dicarboxylate). These are the first structures combining this ligand with lanthanides. All compounds crystallize in the P-1 triclinic system, forming a 2-D coordination network. Luminescence spectra for the Nd3+, Sm3+, and Eu3+ structures show the typical transitions of these ions, through the antenna effect promoted by the ligand. The magnetic properties of Ce3+, Nd3+, Sm3+, Eu3+, Gd3+ compounds were analyzed in terms of the free ion approximation. The variable-temperature susceptibility fitted with a Curie-Weiss law shows the existence of weak magnetic interactions at low temperatures for the Ce3+, Nd3+ and Sm3+ compounds, and paramagnetic behavior for the Gd3+ compound.