Poly-(bis((μ4-1,4-benzenedicarboxylato)-bis(μ2-N,N-dimethylformamide)-(nitrato)-gadolinium (III))) metal organic framework: Synthesis, magnetic and luminescence properties

The title gadolinium benzenedicarboxylate based metal organic framework of chemical formula, C28H36Gd2N6O18, was synthesized under solvothermal conditions in the presence of DMF. The crystal structure is monoclinic, space group P21/c, with unit cell dimensions of a = 17.668(2) Å, b = 20.005(3) Å, c = 10.5382(15) Å, and β = 91.205(2)°, Z = 4, V = 3723.9(9) Å3, ρ (calculated) = 1.889 mg/m3. The unit is defined by four DMF molecules, two nitrate ions, two benzene dicarboxylate (BDC) units and two Gd atoms. Each Gd atom is coordinated to eight oxygen atoms, one from each of four dicarboxylate ions, one from each of two DMF molecules, and two from the single nitrate anion. The three dimensional framework is formed from the interconnectivity of a chainlike arrangement between BDC and Gd only, with one BDC bridging two Gd atoms. Elemental percentage composition was as follows: Gd = 30.9, C = 32.28, H = 3.33, N = 7.28, which are in agreement with calculated values of Gd = 31.7, C = 31.74, H = 3.40, N = 7.94. Gd–O bond lengths ranged between 2.290 and 2.511 Å. The material is paramagnetic due to f7 unpaired Gd electrons, and also displays orange-yellow photoluminescence due to the presence of trace Eu ions in the structure when excited with UV radiation.