Synthesis Structures, and Properties of Functional 2-D Lanthanide Coordination Polymers [Ln2(dpa)2(C2O4)2(H2O)2]n (dpa=2,2′-(2-methylbenzimidazolium-1,3-diyl)diacetate, C2O42- = oxalate, Ln = Nd, Eu, Gd, Tb)

Four two-dimensional frameworks {[Nd(dpa)(C2O4)(H2O)]center dot(H2O)}(n) (1), {[Ln(2)(dpa)(2)(C2O4)(2)(H2O)(2)]center dot(H2O)}(n) (Ln = Eu (2), Gd (3), Tb (4)) (dpa = 2,2'(2-methylbenzimidazolium-1,3-diyl)diacetate, C2O42- = oxalate) have been synthesized under hydrothermal conditions. The networks were generated via formation of sandwich-like dinuclear secondary building blocks of [Ln(2)(dpa)(2)(C2O4)(H2O)(2)] which are linked to each other, resulting in the formation of the subunit of Ln(2)O(2). The variable-temperature magnetic susceptibility studies reveal that complexes 3 and 4 exhibit ferromagnetic interactions, but 2 shows the single Eu3+ ion magnetic behavior. Complexes 2 and 4 show characteristic luminescent properties. The lifetime of 2 is 2.24 ms, but that of 4 is 4.30 ms.