Syntheses, crystal structures, and properties of four polyoxometalate-based metal–organic frameworks based on Ag(I) and 4,4′-dipyridine-N,N′-dioxide

Four new metal–organic frameworks ([Ag₃(dpdo)_3.5(DMF)(PW₁₂O₄₀)]∙H₂O (1), [Ag₃(dpdo)₅(DMF)₂(PW₁₂O₄₀)]∙2CH₃OH (2), [Ag₃(dpdo)₅(DMF)₂(PMo₁₂O₄₀)]∙4H₂O (3), and H_0.5[Ag_4.5(dpdo)₅(DMF)(BW₁₂O₄₀)]∙5H₂O (4); dpdo = 4,4'-dipyridine-N,N'-dioxide) based on polyoxometalates were created, and their properties were examined using infrared (IR) spectroscopy, powder X-ray diffraction, elemental analysis, and comprehensive single-crystal structure investigations. In compounds 1 and 4, the secondary building blocks ([Ag₆O₂₀] and [Ag₃O₁₄] for 1 and 4, respectively) serve as nodes that connect the dpdo ligands with the polyanions ([PW₁₂O₄₀]³⁻ and [BW₁₂O₄₀]⁵⁻ for 1 and 4, respectively) to create a three-dimensional (3D) framework. By joining Ag ions and dpdo ligands and enclosing the polyanions ([PW₁₂O₄₀]³⁻ and [PMo₁₂O₄₀]³⁻ for compounds 2 and 3, respectively) as templates and counterions, compounds 2 and 3 display a two-dimensional (2D) gridlike network. Additionally, the solid state optical, luminescent, and ultraviolet–visible (UV–vis) spectral features of compounds 1–4 as well as the electrochemical characteristics of compounds 1–3 were examined.