Incorporating metal clusters into three-dimensional Ln(III)-Cu(I) coordination frameworks through linear Ligands

By using linear multifunctional ligands with different geometries, three novel three-dimensional (3D) Ln-M heterometallic coordination polymers, [Nd(H2O)(2)(CuI)(2)(nic)(3)]center dot H2O (1) (Hnic = nicotinic acid) and [LnCu(inic)(2)(ox)center dot H2O [Ln = Nd (2), Eu (3); Hinic = isonicotinic acid, H(2)ox = oxalic acid], have been synthesized under hydrothermal conditions. Compound I exhibits a novel 3D coordination framework constructed by Cu4I4 clusters, Nd centers, and nic ligands. Our present work represents the first example of 3D Ln-M heterometallic coordination framework incorporating discrete cubane transition metal clusters covalently bonded to lanthanide centers through linear ligands. An unusual chemical rearrangement from Hinic to ox occurs in the formation of 2 and 3. Compounds 2 and 3 are isostructural and possess the first 3D coordination framework based on the linkage of two-dimensional layers constructed by tetranuclear Ln(2)Cu(2) clusters and inic ligands. Furthermore, the luminescent properties of 3 were studied.