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)(C 2 O 4 )(H 2 O)]·(H 2 O)} n ( 1 ), {[Ln 2 (dpa) 2 (C 2 O 4 ) 2 (H 2 O) 2 ]·(H 2 O)} n (Ln = Eu ( 2 ), Gd ( 3 ), Tb ( 4 )) (dpa = 2,2′-(2-methylbenzimidazolium-1,3-diyl)diacetate, C 2 O 4 2− = 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 (C 2 O 4 )(H 2 O) 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 Eu 3+ 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.