Two magnetic lanthanide-organic frameworks based on semi-rigid tripodal multicarboxylate ligand and different rod-shaped SBUs

Assembly of a semi-rigid tripodal ligand, 3,5-bis(4-carboxyphenoxy)benzoic acid (H(3)bpa), with Ln(2)O(3) (Ln = Dy for 1 and Er for 2) under hydrothermal condition produces two three-dimensional (3-D) lanthanide-organic frameworks (LnOFs), [Dy-2(bpa)(2)(H2O)(3)] (1) and [Er-4(bpa)(4)(H2O)(6)](H2O) (2). Single crystal X-ray diffraction indicates that LnOFs 1 and 2 involve different one-dimensional (1-D) rod-shaped metal-carboxylate secondary building units (SBUs), which are further extended to afford two different 3-D frameworks via the linkage of bpa(3-) ligands. The results demonstrate that the diverse conformations and coordination modes of bpa(3-) ligands play a key role on the formation of the final framework structures. Temperature-dependent magnetic susceptibility measurements reveal the presence of Lren-Lnill ferromagnetic interactions in both LnOFs. (C) 2015 Elsevier B.V. All rights reserved.