Silver coordination metallacycles assembled into microporous materials

Porous solid materials represent one of the most intense areas of study for chemists, physicists, and materials scientists [1]. These systems have found a large number of applications in many fields, such as adsorption, separation and purification, as well as catalysis [2]. We have previously shown that when using the pre-organized thioether functionalized bispyrazolylmethane ligand (LSPh) and silver(I), hexameric metallacycles are formed in solution. In the solid state the role of the counteranion (BF₄^-, PF₆^-, NO₃^-, and CF₃SO₃^-) is of fundamental importance in the way the metallacycles self-assembled into a diversity of 3D supramolecular architectures and cavities. In particular, highly symmetric BF₄^- and PF₆^- favours the formation of crystals with permanent porosity as demonstrated by gas adsorption measurements. In order to modulate the porous properties of these silver coordination polymer (CP), we synthesised a series of differently functionalized bis(pyrazolyl)methane ligands (Figure). The silver complexes were prepared with two types of anions (PF₆^- and CF₃SO₃^-) to investigate their role in the supramolecular arrangements. The structural features and gas sorption properties (CO₂, CH₄ and N₂) of the new silver complexes will be presented. Solid state NMR was employed to investigate the localization of CO₂ within the cavities.