First lanthanide coordination polymers with N,N-dimethylformamide hydrolysis induced formate ligands

A series of isostructural lanthanide organic frameworks with composition [Ln(tpa)(fa)] (Ln = Eu, Gd, Tb; H(2)tpa = terephthalic acid, i.e. 1,4-benzenedicarboxylic acid; Hfa = formic acid, i.e. methanoic acid) has been synthesized through reaction of the corresponding lanthanide nitrates with H2tpa in DMF/H2O mixed solvent under solvothermal conditions (DMF = N,N-dimethylformamide). The formate ligand is in situ generated by hydrolysis of DMF. The dilanthanide-diformate subunits build two-dimensional layers which are shored up by terephthalates, leading to a three-dimensional pillar-layer network. These are the first examples of lanthanide complexes containing the formate ligand originated from hydrolysis of DMF. The dilanthanide-diformate subunit is also the first ever reported. The Eu and Tb complexes emit strong ligand sensitized f-f luminescence. Temperature variable magnetic susceptibility analysis reveals that the Gd(III) atoms are antiferromagnetically coupled (J = -0.0048 cm (1), (H) over cap = -2J (S) over cap (Gd1)center dot(S) over cap (Gd2)). (C) 2011 Elsevier B. V. All rights reserved.