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

Hydrothermal reaction of rare earth oxides with 1H-benzimidazole-5,6-dicarboxylic acid (H(3)bidc) and MnSO4 center dot H2O afforded a series of new three-dimensional (3D) coordination polymers, namely, [Ln(2)Mn(Hbidc)(2)(SO4)(2)center dot 8H(2)O](n) (Ln = Sm (1), Eu (2), Tb (3), Dy (4) and Ho (5)) and (Gd2Mn(Hbidc)(2)(SO4)(2)center dot 7H(2)O](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 Hbidc(2-) 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 Delta E/k(B) = 83.3 K. (C) 2014 Elsevier Ltd. All rights reserved.