Hydrothermal syntheses, crystal structures and properties of 0-D, 1-D and 2-D organic-inorganic hybrid borotungstates constructed from Keggin-type heteropolyanion [alpha-BW{sub 12}O{sub 40}]{sup 5-} and transition-metal complexes

Three novel organic-inorganic hybrid borotungstates {l_brace}[Ni(phen){sub 2}(H{sub 2}O)]{sub 2}H(alpha-BW{sub 12}O{sub 40}){r_brace}.4H{sub 2}O (1), [Cu{sup I}(2,2'-bipy)(4,4'-bipy){sub 0.5}]{sub 2}{l_brace}[Cu{sup I}(2,2'-bipy)]{sub 2}Cu{sup I}(4,4'-bipy){sub 2} (alpha-BW{sub 12}O{sub 40}){r_brace} (2) and {l_brace}[Cu{sup I}(4,4'-bipy)]{sub 3}H{sub 2}(alpha-BW{sub 12}O{sub 40}){r_brace}.3.5H{sub 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){sub 2}(H{sub 2}O)]{sup 2+} cations are grafted on the polyoxoanion [alpha-BW{sub 12}O{sub 40}]{sup 5-} through two terminal oxygen atoms, 2 shows a 1-D infinite chain constructed from [alpha-BW{sub 12}O{sub 40}]{sup 5-} polyoxoanions and {l_brace}[Cu{sup I}(2,2'-bipy)]{sub 2}Cu{sup I}(4,4'-bipy){sub 2}{r_brace}{sup 3+} cations by means of alternating fashion, and 3 displays an unprecedented 2D extended structure built by [alpha-BW{sub 12}O{sub 40}]{sup 5-} polyoxoanions and -Cu{sup I}-4,4'-bipy- linear chains, in which each [alpha-BW{sub 12}O{sub 40}]{sup 5-} polyoxoanion acts as a tetradentate inorganic ligand and provides three terminal oxygen atom and one two-bridging oxygen atom. The presence of Ni{sup II} and W{sup VI} in 1, Cu{sup I} ions and W{sup VI} in 2 and 3 are identified by XPS spectra. The photoluminescence of 2 and 3 are also investigated. - Graphical abstract: Three novel organic-inorganic hybrid borotungstates {l_brace}[Ni(phen){sub 2}(H{sub 2}O)]{sub 2}H(alpha-BW{sub 12}O{sub 40}){r_brace}.4H{sub 2}O (1), [Cu{sup I}(2,2'-bipy) (4,4'-bipy){sub 0.5}]{sub 2}{l_brace}[Cu{sup I}(2,2'-bipy)]{sub 2}Cu{sup I}(4,4'-bipy){sub 2}(alpha-BW{sub 12}O{sub 40}){r_brace} (2) and {l_brace}[Cu{sup I}(4,4'-bipy)]{sub 3}H{sub 2}(alpha-BW{sub 12}O{sub 40}){r_brace}.3.5H{sub 2}O (3) have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, thermogravimetric analyses, X-ray photoelectron spectroscopy and photoluminescence.