Hydrothermal synthesis, crystal structure and properties of three-dimensional Co(II)-4f heterometallic–organic frameworks

Seven novel heterometallic–organic frameworks [Ln₂Co(HBidc)₂(SO₄)₂(H₂O)₈]_n (Ln = Pr (1), Eu (2), Gd (3), Tb (4), Dy (5), Ho (6), Er (7), H₃Bidc = 1H-benzimidazole-5,6-dicarboxylic acid) have been synthesized under hydrothermal conditions and were characterized by elemental analysis, FT-IR, TGA analysis, powder X-ray diffraction and single crystal X-ray diffraction. Complexes 1–7 display a similar 3D (4,4)-connected 4²·8⁴ (PtS) framework. Moreover, the photoluminescence of 2, 4 and 5 and magnetism of 3–5 have also been investigated.