Synthesis, structure, photoluminescence and magnetism of 3d–4f heterometallic coordination polymers bearing benzimidazole-5,6-dicarboxylate

Abstract

Hydrothermal reaction of rare earth oxides with 1H-benzimidazole-5,6-dicarboxylic acid (H3bidc) and MnSO4·H2O afforded a series of new three-dimensional (3D) coordination polymers, namely, [Ln2Mn(Hbidc)2(SO4)2·8H2O]n (Ln=Sm (1), Eu (2), Tb (3), Dy (4) and Ho (5)) and [Gd2Mn(Hbidc)2(SO4)2·7H2O]n (6). Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, FT-IR, powder X-ray diffraction and thermogravimetric analyses (TGA). The single-crystal X-ray diffraction analysis reveals that coordination polymers 1–6 have similar 3D frameworks fabricated through Hbidc2− and SO42− bridging dinuclear lanthanide secondary building units. Moreover, the photoluminescence of complexes 1–4 and magnetism of complexes 4 and 6 have been investigated, 4 exhibits remarkably slow magnetic relaxation behavior with the energy barrier ΔE/kB=83.3K.