title: Lanthanide coordination polymers with "fsy-type" topology based on 4,4'-azobenzoic acid: syntheses, crystal structures, and magnetic properties.
abstract: Seven lanthanide coordination polymers (CPs), [Ln2(azdc)3(DMA)2]n·2n(DMA) (Ln = Sm(III) for 1, Eu(III) for 2, Gd(III) for 3, Tb(III) for 4, Dy(III) for 5, Ho(III) for 6, Er(III) for 7; H2azdc = 4,4'-azobenzoic acid, DMA = N,N-dimethylacetamide), have been successfully prepared with high yields via solvothermal methods and further studied by elemental analyses (EA), powder X-ray diffraction (PXRD), UV-vis spectra, photoluminescent spectra, thermogravimetric analyses (TGA), variable-temperature in situ PXRD analyses, and single-crystal X-ray diffraction. CPs 1-7 all consist of unique 1D lanthanide-carboxylate building units [Ln2(CO2)6]n constructed from the adjacent Ln(III) cations and carboxyl groups of the H2azdc ligands, which can further generate 3D frameworks with "fsy"-type topological structures via the link of azdc(2-). Furthermore, variable-temperature magnetic susceptibility measurements of 1-7 have been investigated. The results indicate that unusual ferromagnetic coupling between adjacent Gd(III) cations exists in 3, which is rarely reported in the Gd(III) complexes only bridged by μ1,3-COO groups. Meanwhile, the magnetic study reveals that 3 displays cryogenic magnetic refrigeration property, whereas 5 shows magnetic dynamics at low temperature.
authors.affiliation: Department of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (MOE), and Collaborative Innovation Center of Chemical Science and Engineering, Nankai University , No. 94, Weijin Road, Tianjin 300071, P. R. China.
authors.forename: Shaowei
authors.initials: S
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Shi
authors.forename: Leilei
authors.initials: L
authors.lastname: Li
authors.forename: Eryue
authors.initials: E
authors.lastname: Duan
authors.forename: Peng
authors.initials: P
authors.lastname: Cheng