Synthesis, structure, fluorescence, magnetism of lanthanide coordination compounds with tridentate carboxylic acid ligands and recognition of Cr2O72-

In order to enrich the rare earth functional materials with fluorescence and magnetic properties, [(M·cpipa·2H 2 O) ·3.75H 2 O] n (M = Pr( 1 ), Eu( 2 ), Gd( 3 ), Dy( 4 ), Tm( 5 ) and Y( 6 )) six three-dimensional porous coordination polymers with the same structure were synthesized by solvothermal method using tridentate carboxylic acid ligand (5-(2-carboxyphenoxy)isophthalic acid (H 3 cpipa)) as the building blocks and combining with rare earth metal salts of Pr, Eu, Gd, Dy, Tm and Y in this paper. The structures of the complexes were characterized by elemental analysis and powder X-ray diffraction, and their solid-state fluorescence and magnetic properties were systematically tested. The results show that the complex 2 exhibits significantly enhanced fluorescence characteristics compared to the ligand, emitting bright red fluorescence under ultraviolet light excitation; its aqueous dispersion has excellent recognition selectivity for Cr 2 O 7 2− , K sv values of complex 2 is 7.7 × 10 3  M −1 and the detection limit is 0.055 μM. Magnetic tests show that complexes 1 , 4 , 5 exhibit antiferromagnetic interactions and complex 3 exhibits ferromagnetic behavior. This study provides new candidate materials and experimental basis for the application of rare earth complexes in fluorescence sensing and molecular magnetism.