A series of three-dimensional lanthanide MOFs: Observation of reversible structural changes controlled by solvent desorption-adsorption, and magnetic properties

A new series of three-dimensional metal-organic frameworks (MOFs), [Ln(2)(dhbdc)(3)(dmf)(4))]center dot dmf (Ln = La, Ce, Pr, Nd, Gd), has been synthesized from benzene-2,5-dihydroxy-1,4-dicarboxylic acid (dhbdc) and five different lanthanide ions Ln(3+) (Ln = La, Ce, Pr, Nd, Gd) by solvothermal synthesis. The title compounds were structurally characterized by means of single crystal X-ray diffraction. They are isostructural and crystallize in the triclinic space group P-1. Thermogravimetric analyses show that the compounds are thermally stable over a long range. Manifestation of possible reversible solvent-induced structural change was observed and studied for the Ce compound by desorption and adsorption of solvent molecules. Magnetic studies on the Gd compound indicate that it can be viewed as a dimer of weakly antiferromagnetic coupled Gd3+ S = 7/2 ions. (C) 2011 Elsevier B.V. All rights reserved.