Hybrid Materials Based On Metal-Organic Coordination Complexes And Polyoxovanadate Clusters: Structure And Magnetic Properties

The design and synthesis of novel hybrid materials have attracted great attention notly stems from their intriguing variety of architectures and incomparable electronicrsatility, but also from their potential applications in the fields as diverse as catalysis,edicine, molecular magnetism and material science. A successful synthetic strategy toepare hybrid materials involves the combination of metal-organic complexes andlyoxovanadates. In this paper, six novel organic-inorganic hybrid complexes:i(4,4'-bpy)2]2[VIV7VV9O38Cl]?(4,4'-bpy)(H2O)6 (1), [Co(4,4'-bpy)2]2[VIV7VV9O38Cl]?,4'-bpy)1.5(H2O)2 (2), [Mn(4,4'-bpy)2]2[VIV7VV9O38Cl]?(4,4'-bpy)(H2O)2.5 (3),i(4,4'-bpy)2]2[VIV7VV9O38F]?(4,4'-bpy)1.5(H2O)3 (4), [Ni(4,4'-bpy)2]2[VIV7VV9O38Br]?,4'-bpy)1.5(H2O)3.5 (5) and [Cu(bpy)]4V4O12·2H2O (bpy = 4,4'-bipyridine)(6) have beendrothermally synthesized through modifying synthetic conditions and starting materials.ructures of the six complexes have been determined by single crystal X-ray diffraction,d the influencing factors on structures and properties of hybrid complexes have beenscussed such as the source of transition metal salts, organic ligands, central templatesd reaction parameters. Complexes 1-5 are isostructural and constructed from cagelike16O38(X)}4-clusters that are incorporated within the 3D scaffolding afforded by(4,4'-bpy)2]n subunits. In addition, helical channels exist in the 3D cationic framework,th disordered 4,4'-bipy molecules filling in the channels. To the best of our knowledge,mplex 4 and 5 is the first examples of hybrid materials that contain [V16O38F]4-and16O38Br]4-cluster, respectively. Otherwise, magnetic susceptibility studies prove thatere exist ferromagnetic interactions in 1, 2, and 3. Ferromagnetic interactions are rare inbrid materials comprised of metal-organic building blocks and mixed-valence cagelikelyoxovanadate clusters. Complex 6 is a two-fold interpenetrating three-dimensionalucture composed of {V4O12}4-rings covalently attached by four {Cu(bpy)}+ moietiesrough the terminal oxo groups of vanadium sites. Complex 6 is the first example ofterpenetrating (3,4)-connected network constructed from metal–organic polymers andlyoxometalates. Interestingly, Cu(I) atoms have a T configuration and {V4O12}4-ringsk to[{Cu(bpy)}+]n chains via two different connecting behaviors. Otheraracterizations for these complexes by elemental analysis, infrared spectroscopy andermogravimetric analysis have also been described.