The syntheses, structures, magnetic and luminescent properties of five new lanthanide(III)–2,6-naphthalenedicarboxylate complexes

• Five new lanthanide polymers based on 2,6-naphthalenedicarboxylic acid were obtained.
• Complexes 1–5 display a 2-D (4,4)-connected framework.
• Magnetic properties of Pr(2), Sm(3), Eu(4) and Gd(5) have been investigated.
• Luminescence studies show that Eu(4) possesses strong luminescence and long lifetime.

Five novel Ln–NDC coordination polymers [Ln(2,6-NDC)(NO3)]·(DMA)2 [Ln = Ln(1), Pr(2), Sm(3), Eu(4), Gd(5)] [Ln = lanthanide, 2,6-H2NDC = 2,6-naphthalenedicarboxylic acid and DMA = dimethylacetamide] have been solvothermally synthesized and structurally characterized by elemental analyses, IR spectra and single-crystal X-ray diffraction. 1–5 are isomorphous, which crystallize in the monoclinic space group Pbca and display two-dimensional (4,4) topologies constructed by [Ln2(COO)4] units and 2,6-naphthalenedicarboxylic acid. Variable-temperature magnetic properties of 2–5 have been investigated. The strong fluorescent emissions of Eu(4) demonstrate that ligand-to-Eu(III) energy transfer is efficient. In addition, thermogravimetric analysis of Gd(5) is also described.

Five novel Ln–NDC (2,6-naphthalenedicarboxylic acid) coordination polymers have been solvothermally synthesized. Complexes 1–5 are isomorphous, which display a 2-D (4,4)-connected framework constructed by [Ln2(COO)4] units and μ4-η1:η1:η1:η1 2,6-naphthalenedicarboxylic acid. Variable-temperature magnetic studies reveal that Pr(2), Sm(3), Eu(4) exhibit antiferromagnetic interactions while Gd(5) shows ferromagnetic couplings between lanthanide cations. Photoluminescence studies show that Eu(4) possesses strong luminescence and long lifetime.Figure optionsDownload as PowerPoint slide