Construction of lanthanide complexes supported by 2,3-dimethoxybenzoic acid and 5,5'-dimethy-2,2'-bipyridine: crystal structures, thermoanalysis, magnetic and fluorescence properties

A series of novel trivalent lanthanide complexes, [Ln(2,3-DMOBA)3(5,5 '-DM-2,2 '-bipy)]2 center dot C2H5OH (Ln = Eu(1), Sm(2), Gd(3), Ho(4) Er(5), Pr(6), Nd(7)) (2,3-DMOBA = 2,3-dimethoxybenzoate, 5,5 '-DM-2,2 '-bipy = 5,5 '-dimethy-2,2 '-bipyridine), have been successfully synthesized and structurally validated by single crystal diffraction. All complexes discussed herein feature a binuclear structure, and contain only one free ethanol molecule, which is interesting in the lanthanide complexes. The coordination number of center Ln3+ ions is nine, showing a distorted monocapped square anti-prismatic coordination geometry. Through a pair of alternating identical C-H center dot center dot center dot O hydrogen bonding interactions between two 2,3-DMOBA ligands on the same lanthanum binuclear unit with 5,5 '-DM-2,2 '-bipy ligands on two neighboring units, the binuclear complexes can form one- The thermal analysis of these complexes are investigated by TG-DSC/FTIR, the result show that the decomposition process of complexes are mainly divided into four stages with the formation of the respective oxides. The visible light emission experiment of complex 1 is carried out, and the characteristic luminescence behavior of intense red light is exhibited. What'more, fluorescence lifetimes as well as the fluorescent quantum yield of complex 1 is calculated. And the magnetic properties of complexes 3-5 are also studied.