Syntheses directed by ionic liquids: structures and properties of six novel lanthanide 1,3,5-benzenetrisbenzoate frameworks

Abstract Reactions of lanthanide nitrate, 1,3,5-benzenetrisbnzoic acid (H 3 BTB) and [RMI]Br ionic liquids (RMI = 1-alkyl-3-methylimidazolium; R = ethyl, propyl or butyl), gave rise to six novel lanthanide–organic frameworks (LOFs) [Ln(BTB)H 2 O], where Ln = Nd 1 , Sm 2 , Gd 3 , Dy 4 , Ho 5 and Er 6 . These compounds have been characterized by elemental analysis, IR spectra, thermogravimetric analysis, single-crystal and powder X-ray diffraction. Compounds 1 – 6 are isostructural and consist of infinite rod-shaped lanthanide-carboxylate building units, which are further bridged by trigonal-planar BTB ligands to give non-interpenetrated open 3D frameworks. The results of variable-temperature magnetic studies have shown that the magnetic interaction between the Ln(III) ions in 3 , 5 and 6 is mainly due to antiferromagnetic coupling as well as the depopulation of the Stark levels.