Synthesis and properties of two new 3D organic–inorganic hybrid compounds constructed from Keggin clusters, pyridine-2,3-dicarboxylate and Ag(I) ions

Two new three-dimensional (3D) organic–inorganic hybrid compounds [K2Ag8(pydc)2(Hpydc)2(H2O)4SiW12O40]·4H2O (1) and (NH4)4[KAg2(Hpydc) (H2O)4.5(H2W12O40)]·4H2O (2) [H2pydc = pyridine-2,3-dicarboxylate], were conventionally synthesized and characterized by IR, TG, elemental analysis, and single-crystal X-ray diffraction technique. In 1, six-nucleus [Ag6(Hpydc)2]4+ and two-nucleus [Ag2(pydc)2]2− are linked alternately through oxygen atoms of the carboxylic group leading to a grid-like 2D layer. These layers are supported by SiW12 clusters, giving a unique 3D framework. In 2, each W12 cluster connects five Ag ions and three K ions, and each Ag1 or Ag2 ion links three W12 clusters, forming a double chain. Furthermore, these double chains are linked together through K+ ions to form a 3D framework. The solid-state luminescence properties of compounds 1, 2 and pyridine-2,3-dicarboxylate have been studied at room temperature.

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► The compounds are the first examples of silver hybrid compounds of H2pydc–Keggin POM.
► H2pydc ligands have different coordination modes.
► Six-nucleus [Ag6(Hpydc−)2]4+ and two-nucleus [Ag2(pydc2−)2]2− are formed in 1.