2D lanthanide coordination polymers constructed from a semi-rigid tricarboxylic acid ligand: crystal structure, luminescence sensing and color tuning

Three lanthanide polymers {[Ln(TMCA)(DEF)(H2O)]center dot(CH3CN)}(n) (Ln = Eu 1; Tb 2; Gd 3; H(3)TMCA = 4',4',4'-[(trimethylamino)]-tris[(1,1'-biphenyl)-2-carboxylic acid)] were synthesized under solvothermal conditions. The coordination polymers were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction. Single crystal X-ray diffraction analyses showed that the complexes 1, 2 and 3 are isostructural 2D coordination networks with a point symbol of {4(4).6(2)}. Complexes 1 and 2 exhibit red and green emission, assigned to the D-5(0) -> F-7(J) (J = 0-4) transitions of the Eu3+ ion and D-5(4) -> F-7(J) (J = 6-2) transitions of the Tb3+ ion, respectively. The luminescence explorations reveal that the Eu-MOF possesses favorable selectivity and sensitivity for testing Fe(3+ )in CH3OH solutions. Additionally, color tuning was easily achieved by varying the europium : terbium metal ratios in the reaction mixtures.