Two-Dimensional Frameworks Based on Ag(I)-N Bond Formation: Single Crystal to Single Molecular Sheet Transformation.

A series of new two-dimensional coordination framework materials, based on Ag(I)-N bond formation, has been synthesized and structurally characterized by single crystal methods. Reactions between the poly-monodentate bridging ligand N,N'-((1r,4r)-cyclohexane-1,4-diyl)bis(1-(pyridin-3-yl)methanimine), L1, and silver salts yield compounds {[Ag(L1)(MeCN)](CFSO)}, 1, {[Ag(L1)(PFO)]·HO}, 2, and {Ag(L1)(tosylate)}, 3. The frameworks of these materials exhibit two distinct net topologies: 3.4.5 (1 and 2) and 4.6 (3). In all cases, L1 ligands are found to be fully saturated, in terms of metal ion binding, with both sets of pyridyl and imino N atoms involved, though in 1 and 2, crystallographically independent L1 moieties also display pyridyl-only binding. Either solvent (1) or the anion (2 and 3) acts as a terminal ligand to support interlayer interactions in the solid state. For 2 and 3 the molecular sheet orientation lies in the plane of the largest crystal face, indicating that crystal growth is preferentially driven by coordinate bond formation. Despite the relatively labile nature, typical of such Ag(I)-N bonds, solvent-based exfoliation of crystals of 3 was shown to provide dispersions of large, μm, flakes which readily deposit on oxide surfaces as single-molecule sheets, as revealed by atomic force microscopy.