Two 3D Coordination Frameworks Based on Nanosized Huge Ln26 (Ln = Dy and Gd) Spherical Clusters

Two novel three-dimensional (3D) coordination polymers Zn1.5Dy26(IN)(25)(CH3COO)(8)(CO3)(11)(OH)(26)(H2O)(29) (1) and Zn1.5Gd26(IN)(26)(CH3COO)(7)(CO3)(11)(OH)(26)(H2O)(28) (2) based on the linkages of large nanosized spherical hydroxo Ln(26) clusters and zinc centers by organic ligands have been hydrothermally synthesized. Metal organic framework (MOF) 1 crystallizes in the triclinic space group P (1) over bar, with a = 21.107(2) angstrom, b = 21.185(2) angstrom, c = 36.323(4) angstrom, alpha = 89.001(2)degrees, beta = 82.486(2)degrees, gamma = 68.359(2)degrees, V = 14960(3) angstrom(3), Z = 2. MOF 2 crystallizes in the triclinic space group P (1) over bar, a = 19.6213(15) angstrom, b = 22.1850(17) angstrom, c = 34.654(3) angstrom, alpha = 88.5340(210)degrees, beta = 85.6520(10)degrees, gamma = 72.9790(19)degrees V = 14382.5(19) angstrom(3), Z = 2. Structural analysis indicates that both 3D polymers can be constructed using the building unit of CO3@Ln(26) (Dy for 1, Gd for 2) and exhibit similar topological frameworks. During the synthesis, three ligands were used. CO32- plays a very important role in the formation of the spherical Ln(26) cluster. CH3COO- makes the Ln(26) cluster stable and reduces steric restriction. The isonicotinate (1N) stabilizes the cluster and links the clusters and the Zn centers.