Design, Synthesis And Characterization Of Organic-Inorganic Hybrid Compound Base On Polyoxoniobates

Polyoxoniobates have attracted extensive attention because of their potential applications in nuclearwaste treatment and photolysis of water to yield molecular hydrogen. However, a rapid development of polyoxoniobate chemistry only occurs in recent decades, because polyoxoniobates (PONbs) are found to be difficultly obtained by usual acidifications at ambient conditions. The aim of this thesis is the synthesis of new organic-inorganic hybrid compounds base on polyoxoniobates utilizing hydrothermal technique. The study on synthetic strategy for these hybrid compounds and the exploration of relationships between structures and ratio of raw materials are also carried out.Seventeen new organic-inorganic hybrid compounds based on polyoxoniobates was successfully synthesized under hydrothermal conditions and structurally characterized by elemental analyses, IR, EDX, SEM, TG, ICP and single crystal X-ray diffractions.1. Six new organic-inorganic hybrid compounds based on unusual Sb-bicapped Keggin-type [HBTNb12O40Sb2]8-(T= Si, Ge, P, As or V) polyanions and [Cu(en)2]2+ (or H2en2+) were synthesized. In compound 1-6, two Sb atoms, in a distorted square pyramidal coordination geometry, oppositely cap on two{Mb4O4} window of the{?-TNb12} core, then the symmetry of the a-Keggin-type cluster is lowered from Td to D2d. In the presence of Sb(?), five kinds of usual atoms were introduced to the hetero atom center of Keggin-type heteropolyoxoniobates. Especially, compound 4 is the first As-centered Keggin-type heteropolyoxoniobate. In addition,3D supermolecule structures in compound 1-6 were formed via H-bonds between [HnTNb12O40Sb2]8- and [Cu(en)2]2+ (or H2en2+). Moreover, compound 6 can be used as photocatalysts to decompose methylene blue dye. [Cu(en)2(H2O)]4[H2SiNb12O4oSb2] ·18H2O (1) [Cu(en)2(H2O)]4[H2GeNb12O4oSb2] · 18H2O (2) [Cu(en)2(H2O)]4[HPNb,2O40Sb2] · 18H2O (3) [Cu(en)2(H2O)]4[HAsNb12O4oSb2] · 18H2O (4) [Cu(en)2(H2O)]4[HVNb12O40Sb2] · 18H2O (5) (H2en)5[SiNb12O40Sb2]·5H20 (6)2. In compounds 7 and 8, Each one consists of an unusual dimer [(TNb12O38Sb2)2(?2-O)2]16- anion formed by two Keggin-type{?-TNb12St2} clusters via two ?2-O. The unusual C2h anti symmetry in the dimer was firstly found in the structures of the Keggin-type heteropolyoxoniobates. In the compounds, six [Cu(en)2]2+ fragments decorate a {(TNb12O39Sb2)2} cluster via Cu-0 to form a six-supporting heteropolyoxoniobates. [Cu(en)2]{[Cu(en)2]3[SiNb12O39Sb2]}·11H2O (7) [Cu(en)2]{[Cu(en)2]3[GeNb,2O39Sb2]}·11H2O (8)3. Two novel microtubes based on heteropolyoxoniobate were successfully synthesized under hydrothermal conditions. The inner diameter and wall thickness of the microtube are in the ranges of 10-50 ?m and 10-40 ?m, respectively. Compounds 9 and 10 are the first two examples of tubular materials based on heteropolyoxoniobates. The single-crystal X-ray diffraction analysis reveals that the two compound are consisted of novel Sb-bicapped Keggin-type [?-HTNb12O40Sb2]9- polyanions and [Cu(en)2]2+ cations. In addition, there are channels filled by lattice water molecules along a axis. [Cu(en)2(H2O)2]6{[Cu(en)2(H2O)]2[Cu(en)2][HSiNb12O40Sb2]2}·8H20 (9) [Cu(en)2(H2O)2]6{[Cu(en)2(H2O)]2[Cu(en)2][HGeNb12O40Sb2]2} · 8H2O (10)4. Compounds 11-13 on the basis of crescent-shape [SiNbigO54]14- polyanions with C2v symmetry and [Cu(en)2]2+ cations were successfully synthesized under hydrothermal condition. In compound 11-13, [Cu(en)2]2+ fragments decorate a{SiNb18O54} cluster via Cu-0 coordination bond to form a bi-supporting(in compound 11), six-supporting(in compound 12) or four-supporting(in compound 13) heteropolyoxoniobate clusters. K2Na(H2en)[Cu(en)2(H2O)2]3.5{[Cu(en)2](SiNb18O54)}·18H2O (11) Na2[Cu(en)2(H2O)][Cu(en)2(H2O)2]0.5{[Cu(en)2]4.5(SiNb18O54)}·14H2O (12) Na4.5[Cu(en)2(H2O)2][Cu(en)2(H2O)]{[Cu(en)2]2.5(Ho.5SiNb18054)}·16H2O (13)5. Compounds 14-17 based on Nyman-type analogue [TiNb9O28]7- polyanions and [Cu(en)2]2+ cations were successfully synthesized under hydrothermal condition. In compounds 14 and 15, [Cu(en)2]2+ fragments link{TiNb9O28} clusters via Cu-0 coordination bond to form 1D structure. In compound 16, [Cu(en)2]2+ cations link{TiNb9O28} clusters via Cu-0 coordination bond to form 2D structure along [011] plane. In compound 17, every [TiNb9O28]7- clusters are linked via Cu-0 coordination bond to form a tri-supporting cluster. The two crystallography independent cluster are bridged by one [Cu(en)2]2+ to form a dimer. [Cu(en)2(H2O)2]3{(OH)(TiNb9O28)[Cu(en)2]}·13H2O (14) [Cu(en)2(H2O)2]3{(TiNb9O28)(OH)[Cu(en)2]}·11H2O (15) [Cu(en)2(H2O)]{(HTiNb9O28)[Cu(en)2]2}·9H2O (16) [Cu(en)2(H2O)2][Cu(en)2(H2O)]{(TiNb9O28)[Cu(en)2]5} ·17H2O (17)...