Novel Hybrids Constructed from Keggin-Polyoxometalate and Mixed Copper Complex

Abstract  Two new Keggin-polyoxometalate hybrids, {Cu₂(4,4′-bpy)₂]PW₁₀^VIW₂^VO₄₀]}Cu₂(obpy)₂]₄ · 2 H₂O (1) and {Cu₄(2,2′-bpy)₄(4,4′-bpy)₃]SiW₁₂O₄₀]} · 2H₂O (2) (4,4′-/2,2′-bpy = 4,4′-/2,2′-bipyridyl, Hobpy = 6-hydroxy-2,2′-bipyridyl), were hydrothermally synthesized and structurally characterized. Gillard type hydration of 2,2′-bipy is observed during the synthesis of 1, resulting in a new obpy ligand in situ. X-ray structural analyses show that 1 consists of 1D hybrid chain {Cu₂(4,4′-bpy)₂]PW₁₀^VIW₂^VO₄₀]}_∞ and Cu₂(obpy)₂] dimer, whereas 2 possesses 1D hybrid structure based on Keggin-type SiW₁₂O₄₀]⁴⁻ anions and tetra-nuclear copper complexes Cu₄(2,2′-bpy)₄(4,4′-bpy)₃]⁴⁺. Both compounds present interesting supramolecular architectures based on π–π stacking and hydrogen bonds. Graphical Abstract  Compounds {Cu₂(4,4′-bpy)₂]PW₁₂O₄₀]}Cu₂(obpy)₂]₄ · 2H₂O (1) and Cu₄(2,2′-bpy)₄(4,4′-bpy)₃]SiW₁₂O₄₀] · 2H₂O (2) were hydrothermally synthesized. 1 features that the Cu₂(obpy)₂] dimers based on in situ generated obpy ligands are stumped between the layers where 1D hybrid chain {Cu₂(4,4′-bpy)₂]PW₁₂O₄₀]}_∞ locates, while 2 exhibits 1D chain-like structure based on anions SiW₁₂O₄₀]⁴⁻ and tetra-copper complexes Cu₄(2,2′-bpy)₄(4,4′-bpy)₃]⁴⁺.