Three LnIII coordination compounds based on 1,1′,1″-(benzene-1,3,5-triyltris(methylene))tris(4-carboxypyridinium)tribromide: Synthesis, structures, and properties

AbstractAn exploration of reactions of 1,1′,1″-(benzene-1,3,5-triyltris(methylene))tris(4-carboxypyridinium)-tribromide (H3LBr3) with LnIII salts has led to the formation of three complexes, {[LnL(H2O)2]·3(NO3)·6H2O} (Ln = Eu (1), Gd (2), and Tb (3)). Single-crystal X-ray analyses revealed that these complexes are isomorphous and have 3-D, channel-like structures, in which the carboxylic acids are fully deprotonated with syn–syn μ2-η1:η1 type bridging modes and L ligands in a chair-shaped configuration. Both 1 and 3 showed strong luminescence upon excitation. Magnetic measurements were performed for 2 and 3. The magnetic studies show that very weak antiferromagnetic couplings exist between GdIII and GdIII in 2. Moreover, powder X-ray diffraction, infrared spectroscopy, and elemental analysis were also performed.