Synthesis, Structures And Properties Of Metal Borates

Metal borates are of current interest due to their rich structural chemistry and diverse applications in mineralogy, catalysis, ion-exchange and nonlinear optical materials. Up to now, main group borates, transition metal borates and lanthanide borates have been successfully synthesized through different synthetic approaches. The Pb2+ion shows flexible coordination environments and stereochemically active lone pairs, which has a strong tendency to form lead oxo/hydroxo clusters and nonlinear-optical, so studies of lead borates have attracted much more attention in recent years.Four metal borates, Pb6B6O14(OH)2(H2O), Pb6B4O11(OH)2, PbBaB5O9(OH)-(H2O), BaB3O4(OH)3℉0.5H2O have been synthesized by using solution method at different hydro thermal and temperatures reaction. The crystal of X-ray diffraction data are collected by X-ray single crystal diffractometer, the SHELX-97software are used to resolve the crystal structure, and all of the compounds have been characterized by PXRD, IR, TGA, UV-vis-NIR diffuse reflectance spectra.A new lead borate constructed of different cluster building units of{B4} and {Pb6} is obtained via a simple hydrothermal process using Pb(BO2)2·H2O as the starting material. The space group of Pb6B4O11(OH)2is Pnma, crystal cell parameters is a=13.3931(15) A, b=13.0149(16) A, c=7.8019(10) A, a=β=γ=90.00°, V=1359.9(3) A3, Z=4. Pb6B4Oii(OH)2is built by different cluster building units of B4O9{B4} and Pb6O4{Pb6}, has been obtained under mild hydrothermal conditions, each {B4} unit is linked to five{Pb6} clusters, while each{Pb6} cluster is linked to the five nearest{B4} units and four{Pb6} units, which give rise to the binodal (5,9)-connected lead borate frameworks. Another new lead borate Pb6B6Oi4(OH)2(H2O) is obtained when a simple reagent NaBO34·H2O add to the reaction system Pb(BO2)2·H2O. The space group of Pb6B6O14(OH)2(H2O) is P21/c, crystal cell parameters is a=6.6006(8) A, b=13.3561(17) A, c=17.888(2) A, β=93.620(7)°, V=1573.8(3) A3, Z=4. Pb6B6O14(OH)2(H2O) is built by different cluster building units of B6O14(OH)(B6) and Pb6O5(OH)(Pb6), has been obtained under mild hydro thermal conditions. Each (B6) cluster is linked with seven(Pb6) clusters and vice versa that give rise to the first7-connected lead borate frameworks.A new noncentrosymmetric borate-based material PbBaBsO9(OH)(H2O) is obtained when other metal ions Ba2+and borate Na2B4O7℉10H2O are introduced into the reaction system Pb(BO2)2℉H2O. The space group of PbBaB5O9(OH)(H2O) is Cc, crystal cell parameters is a=11.3361(6) A, b=6.6234(6) A, c=12.9266(9) A,β=115.152(6)°, V=878.55(11) A3, Z=4. The structure of PbBaB5O9(OH)(H2O) displays a3D anionic network with1D channels constructed by B5O11(OH) units and Pb2+cations, Ba2+cations are located at the above channels. Interestingly, PbBaBs-O9(OH)(H2O) is noncentrosymmetric crystal and display a moderate second-harmonic generation (SHG) response comparable to that of KH2PO4(KDP), and it is phase matchable.A new lead borate BaB3O4(OH)3·0.5H2O is obtained when Pb(BO2)2·H2O is eliminated from the reaction system of PbBaBsO9(OH)(H2O). The space group of BaB3O4-(OH)3·0.5H2O is P21/c, crystal cell parameters is a=7.2552(4) A, b=10.0554(7) A, c=8.6347(5) A, β=111.402(4)°, V=586.50(6) A3, Z=4. its structures features a1D zigzag chain structure in which (B3Og)5-clusters are bridged by corner-sharing O atoms, the Ba2+cations are located at the small voids of the anionic frameworks.Those search results of this paper enrich the contents of borate chemistry, which are of significance to the exploitation of the lead borates NLO materials.