First 3D 3d-4f interpenetrating structure: synthesis, reaction, and characterization of {[LnCr(IDA)2(C2O4)]}n.

The hydrothermal reaction of Cr(NO3)3, Ln2O3, and iminodiacetate acid (H(2)IDA) in the molar ratio of 1:1:3 produced {[LnCr(IDA)2(C2O4)]}n (Ln = Eu, 1; Sm, 2), which represent the first 3D 3d-4f interpenetrating coordination polymers. In the reaction, the H(2)IDA ligands partly decompose into oxalate anions (ox), which connect Ln(III) ions to form 1D {Ln(ox)}n chains. Each of the Cr(III) ions is tridentate-coordinated by two IDA ligands, which act as tetradentate metalloligands to link {Ln(ox)}n chains to form 3D open networks. The two open networks interpenetrate each other to form nonporous products. 1 and 2 are thermally stable up to 327 and 360 degrees C, respectively. Both of complexes show normally paramagnetic behavior. The luminescent results imply that the energy transfers from Ln(III) to Cr(III) are strong.