Influence of Anions in Silver Supramolecular Frameworks: Structural Characteristics and Sorption Properties.

The complexation of a preorganized thioether-functionalized bis­(pyrazolyl)­methane ligand (L) with silver precursors produces supramolecular structures organized at two hierarchical levels: [AgL]₆(X)₆ metal–organic cyclic hexamers and their organization in 3D architectures. The cyclic toroidal hexamers of 22–26 Å external diameter are found to be stable already in solution before self-assembly into the crystalline state. In the 3D lattice, the hexameric building block are arranged in different highly symmetric space groups as a function of a variety of anions (cubic <i>Fd</i>3̅ with PF₆^– or BF₄^– and rhombohedral <i>R</i>3̅ with CF₃SO₃^– or NO₃^–) and form cavities with the geometrical shapes of Platonic solids (tetrahedron and octahedron) that can be occupied by a variety of solvent molecules. Upon evacuation, cubic crystals can produce stable frameworks with permanent porosity, which can absorb reversibly several vapors, CO₂ and CH<sub>4