Novel lanthanide complexes constructed from 3, 4-dimethoxybenzoic acid: crystal structures, spectrum and thermochemical properties

Four novel lanthanide complexes [Ln(3,4-DMOBA)(3)(H2O)(2)].H2O.C2H5OH (Ln = Sm(1), Tb(2), DY(3), Ho(4); 3,4-DMOBA =3, 4-dimethoxybenzoate) have been hydrothermal synthesized and characterized. Structural analyses reveal that adjacent lanthanide ions are connected by 3,4-DMOBA ligands adopting bridging bidentate mode to generate one-dimensional (1-D) structure with the uncoordinated water and ethanol molecules. 1-D structures are linked by hydrogen bonds to form a three-dimensional (3-D) structure, which is rarely observed in lanthanide carboxylic acids complexes. Under the radiation of UV light, complex 2 exhibits the characteristic emission of Tb3+ ion.(D-5(4) -> F-7(6-3)). The thermal decomposition mechanism is investigated by TG-FTIR technology. IR spectra of the evolved gases show that the uncoordinated water and ethanol molecules lose in the first step. And then 3,4-DMOBA ligand is decomposed into H2O, CO2 and other gaseous molecules as well as the gaseous organic fragments. (C) 2015 Elsevier B.V. All rights reserved.