Controllable assembly, characterization and catalytic properties of a new Strandberg-type organophosphotungstate.

Using phenylphosphonic acid, simple tungstate and copper(ii) compounds as starting materials, an organic-inorganic hybrid Strandberg-type organophosphotungstate, {[(Cu(H2O)(μ-bipy))2(C6H5PO3)2W5O15]}n (bipy = 4,4'-bipyridyl) (1), was assembled successfully under hydrothermal conditions and characterized by physico-chemical and spectroscopic methods. Compound 1 represents the first example of a transition metal complex modified organophosphotungstate cluster. In the crystal structure of compound 1, the polymeric 1-D {Cu-bipy}n chains are interconnected by [(C6H5PO3)2W5O15](4-) (abbreviated as {(C6H5P)2W5}) units into a 3-D framework. A hollow Keggin isopolytungstate [H2W12O40](6-) ({W12})-Cu(ii) coordination polymer, {[Cu(bipy)2((μ-bipy)Cu(bipy))2(H2W12O40)]·12H2O}n (2), was obtained at different molar ratios of the starting materials and pH. The two Cu(ii) coordination polymers exhibit good acid-catalytic activity for the synthesis of cyclohexanone ethylene ketal. Their fluorescence properties were studied.