Synthesis and characterization of polymorphs of photoluminescent Eu(III)-(2,5-furandicarboxylic acid, oxalic acid) MOFs

A novel metal organic framework (MOF) formulated as [Eu(H2O)(2)(fdc)(ox)(0.5)center dot(H2O)] n (1, fdc(2-)=2,5-furandicarboxylate, ox(2-)= oxalate), was hydrothermally synthesized via in situ ox(2-) generation from the partial decomposition of the fdc(2-) ligand. This material crystallizes in the monoclinic space group C2/c, unit cell parameters of 1: a=16.7570(10), b=10.5708(7), c=13.5348(14) angstrom, beta=116.917(2)degrees (Z=8), and exhibits a three-dimensional (3D)-porous framework, with guest water molecules residing in the channel linking all other ligands (H2O, ox(2-)and fdc(2-)) via hydrogen bonding interattions. Compound 2 is a polymorph of 1 crystallizing in monoclinic P21/c space group. The photoluminescence properties of 1 and 2 were studied at room temperature. The spectra show the typical Eu3+ red emission and the differences observed reflects the slightly different structures of these polymorphs. (C) 2013 Elsevier Inc. All rights reserved.