Synthesis And Structure Chemistry Of The Novel Polyborate Vanadate Materials

Polyoxovanadium borate is a new field of polyoxometalate chemistry. The coordination geometries of V and O contain VO₆ octahedron, VO₅ square pyramid and VO₄ tetrahedron. The coordination geometries of B and O contain BO₄ tetrahedron, BO₃ triangle; and many structures are based on them. The various connection modes between V-O polyhedron and B-O polyhedron allow polyoxovanadium borates to be structurally very diverse. We carried out the study about hydrothermal synthesis of polyoxovanadium borates and intended to find the relationship between properties and structures based on summary of literature search systematically. So far we had made achievements on such aspect: 1. Five novel polyoxovanadium borates and two lead borates have been designed and synthesized. X-ray single crystal diffractometer technology was employed to determine their structures: (H₂en)₄[(VO)₆(B₁₀O₂₂)₂]·(H₃O)7 1 Na₂(H₂en)₂{(VO)₁₀[B₁₄O₃₀(OH)₂]₂}{Mn₄(C₂O₄) [B₂O₄(OH)₂]₂}Mn(H₂O)₂·(H₂O)₁₈ 2 {(VO)₁₀[B₁₄O₂₈(OH)₄]₂}{Zn₄(B₂O₄)(BO₃)₂} [Zn(NH₂CH₂CH₂NH₂)₂]6 3 (H₂en)₃[(VO)₁₂O₄{B₈O₁₇(OH)₄}₂{Na(H₂O)}₂] ·(H₃O)₂ (H₂O)_6.5 4 [Na(H₂O)₂][Cu(en)₂]₂[(VO)₁₂B₁₈O₄₂(OH)₆] ·(H₃BO₃)(H₃O)₁₀(H₂O)₄ 5 [Pb₆(LiB₁₂O₂₄)]·OH 6 Pb₆[B₁₂O₂₁(OH)₆] 7 Among these compounds, the compound 1 templated by organic amine is composed of [V6B20O50] cluster anion. Compound 2 3 are consist of unprecedented [V10B28O74] cluster anions. In compound 2, the [Mn(H2O)2]2+ and [Na(H2O)2]2+ units connect the cluster anions to 2D layers. In compound 3, the [Zn(en)2]2+ units link the cluster anions to 2D layers. Compound 4 is composed of [V12B16O58] cluster anion and unusual dinuclear units linking the cluster anion into 1D chains. Compound 5 is the first polyoxovanadium borate with 3D framework structure, which consists of [V12B18O60] cluster anions, Na+ and [Cu(en)2]2+ units. Moreover, Compound 6 and 7 are two novel lead borates. Among them, compound 6 is the first lead borate with polyborate lead cluster unit. Compound 7 is a chiral lead borate exhibiting distinct NLO properties. We study their properties thoroughly with IR, DRS and TGA. Some instructive and interesting results were obtained according to the results. In IR spectra, we ascribed the characteristic peaks of polyoxometalates to corresponding vibration frequencies and found the characteristic peaks related to the bond length between metals and oxygens, the coordination surroundings. In UV-Vis DRIS spectra, the LMCT bands of Ot→M were found at about 205 nm and the LMCT bands of Ot→M split into two peaks. We find the fact that with the rise of temperature, compounds have two ranges of weight losing, corresponded to the loss of crystal waters and organic molecules respectively from TGA diagram. In addition, we designed and made the IR appurtenances for controlling magnetism. And we first introduced the 2D IR correlation spectroscopy to study the polyoxometalates and the results indicate that the subtle structural changes of POMs can be clearly probed by the generalized 2D IR correlation spectroscopy. The dynamic information obtained by the 2D IR is valuable to the in-depth study of POMs, such as exploring the mechanism of POMs catalysis, investigating the magnetic exchange process in magnetic POMs and researching the interaction between the building blocks of POMs. Furthermore, the calculation of [(VO)12O4{B8O17(OH)4}2]12-cluster anion and Pb6[B12O21(OH)6] 7 have been carried out on the quantum chemistry method. Weobtained their reactive centers based on the calculated net charge. In [(VO)12O4{B8O17(OH)4}2]12-anion cluster, μ2-O and Ot are the reactive centers in nucleophilic reaction. So they are easy to be hydrogen bond or to be attacked by metallic cations. In the anion clusters, μ3-O is the activity centers catalysis. As far as compound 7 concerned, we obtained and analyzed the crystal energy band structure, the total and partial density of states, and optical response functions. The calculating results demonstrate that compound 7 is insulator with band gaps at 3.4324eV. The O-2p states create the top of valence bands and the Pb-6d states form the low conduction bands. Moreover, the results of optical response functions indicate the refractive indices are different in x, y and z direction. Thus, the compound have the potential values as double refractive index materials.