Hydrothermal syntheses, crystal structures and properties of 0-D, 1-D and 2-D organic-inorganic hybrid borotungstates constructed from Keggin-type heteropolyanion [alpha-BW12O40](5-) and transition-metal complexes

Three novel organic-inorganic hybrid borotungstates {[Ni(phen)(2)(H2O)](2)H(alpha-BW12O40)}center dot 4H(2)O (1), [Cu-I(2,2'-bipy)(4,4'-bipy)(0.5)](2){[Cu-I(2,2'-bipy)](2)Cu-I(4,4'-bipy)(2)(alpha-BW12O40)} (2) and {[Cu-I(4,4'-bipy)](3) H-2(alpha-BW12O40)}center dot 3.5H(2)O (3) (phen = 1,10-phenanthroline, 2,2'-bipy = 2,2'-bipyridine, 4,4'-bipy = 4,4'-bipyridine) have been hydrothermally synthesized and structurally characterized by elemental analyses, IR, UV spectra, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), single-crystal X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and photoluminescence. The structural analysis reveals that 1 consists of a 0-D bisupporting polyoxometalate Cluster where two [Ni(phen)(2)H2O)](2+) cations are grafted on the polyoxcanion [alpha-BW12O40](5-) through two terminal oxygen atoms, 2 shows a 1-D infinite chain constructed from [alpha-BW12O40](5-) polyoxoanions and {[Cu-I(2,2'-bipy)](2)Cu-I(4,4'-bipy)(2)](3+) cations by means of alternating fashion, and 3 displays an unprecedented 2D extended structure built by [alpha-BW12O40](5-) polyoxoanions and -Cu-I-4,4'-bipy- linear chains, in which each [alpha-BW12O40](5-) polyoxoanion acts as a tetradentate inorganic ligand and provides three terminal oxygen atom and one two-bridging oxygen atom. The presence of Ni-II and W-VI in 1, Cu-I ions and W-VI in 2 and 3 are identified by XPS spectra. The photoluminescence of 2 and 3 are also investigated. (C) 2009 Elsevier Inc. All rights reserved.