Metal-ion controlled solid-state reactivity and photoluminescence in two isomorphous coordination polymers

Abstract

Reactions of [M(NH₃)₂]OH (M = Ag and Cu) and 4-(1H-pyrazol-4-yl)pyridine (Hpypz), using p-xylene (C₈H₁₀) as the template, gave isomorphous two-dimensional porous metal azolate frameworks [Ag₂(pypz)₂]·0.5C₈H₁₀ (MAF-36(Ag), 1·g) and [Cu₂(pypz)₂]·0.5C₈H₁₀ (MAF-36(Cu), 2·g). Powder and single-crystal X-ray diffraction studies showed that, upon guest removal, 1·g transformed into a three-dimensional nonporous framework [Ag₆(pypz)₆] (1′), while 2·g can retain its porous two-dimensional structure. Depending on the metal ion, framework flexibility/rigidity, and/or porosity, 1·g and 2·g, as well as their guest-free derivatives, showed distinctly different photoluminescence and guest-responsive behaviors.