title: A series of 3d-4f heterometallic three-dimensional coordination polymers: syntheses, structures and magnetic properties.
abstract: Seven lanthanide-cobalt heterometallic three-dimensional coordination polymers: {[Ln(3)Co(2)(BPDC)(5)(HBPDC)(H(2)O)(5)](ClO(4))(2)·mH(2)O}(n) (Ln = Eu (1, m = 10.25), Gd (2, m = 8), Tb (3, m = 9.5), Dy (4, m = 11), Ho (5, m = 10.5), Tm (6, m = 11), Lu (7, m = 10.25); BPDC = 5,5'-dicarboxylate-2,2'-dipyridine anion) were structurally and magnetically characterized. Compounds 1-7 crystallize in the orthorhombic space group Pbca, featuring a 3D sandwich framework. Magnetic properties of 2-6 have been investigated by using DC (direct current) and AC (alternating current) susceptibility measurements. Among these compounds, only compound 4 displays significant frequency dependence, albeit without reaching the characteristic maxima above 2 K, implying slow magnetic relaxation behavior in 4. After the application of a DC field, good peak shapes of AC signals were obtained and the energy barrier ΔE/k(B) = 62.89 K and the preexponential factor τ(0) = 6.16 × 10(-8) s. To our knowledge, 4 has the highest energy barrier in Ln-Co SMM systems hitherto.
authors.affiliation: Department of Chemistry, Key Laboratory of Advanced Energy Material Chemistry, MOE, Nankai University, Tianjin 300071, P. R. China.
authors.forename: Ming
authors.initials: M
authors.lastname: Fang
authors.forename: Peng-Fei
authors.initials: PF
authors.lastname: Shi
authors.forename: Bin
authors.initials: B
authors.lastname: Zhao
authors.forename: Dong-Xue
authors.initials: DX
authors.lastname: Jiang
authors.forename: Peng
authors.initials: P
authors.lastname: Cheng
authors.forename: Wei
authors.initials: W
authors.lastname: Shi