Conformational 2-Fold Interpenetrated Uranyl Supramolecular Isomers Based on (6,3) Sheet Topology: Structure, Luminescence, and Ion Exchange.

Six new 2-fold interpenetrated uranyl coordination polymers with two distinct types of (6,3)-net layers, (H3O)[(UO2)(L)]·H2O (1), (Hbipy)[(UO2)(L)]·H2O (2), (Hbib)[(UO2)(L)]·H2O (3), (H2dib)[(UO2)2(L)2]·H2O (4), [Zn(H2O)6][(UO2)2(L)2]·5H2O (5), and (NH4)[(UO2)(L)]·H2O (6), (bipy = 2,2'-bipyridine, bib = 4,4'-di(1 H-imidazol-1-yl)-1,1'-biphenyl, and dib = 1,4-di(1 H-imidazol-1-yl)benzene), were hydrothermally prepared from a tripodal polycarboxylate ligand, tri(4-carboxyphenyl)phenylsilane (H3L), with different N-bearing organic templates as the stacking templates and charge compensators. Structural analyses indicate that these compounds comprise two sets of conformational supramolecular isomers because of the same framework compositions but different conformations of the carboxylate ligands. The solid-state emission spectra of compounds 1-6 were recorded. Ion-exchange studies revealed that the ammonia hydrate in 6 can be selectively substituted by alkali metal cations with appropriate ionic radii, and that the resulting structures remain stable, as demonstrated by crystallographic characterization.