Synthesis, Characterization And Catalytic Properties Study On Aminopyridine And Aminopyrimidine Polyoxometalates Compounds

The design and synthesis of organic-inorganic hybrid have become a significantarea of research for chemists in recent years due to the possibility of combiningdifferent characteristics of the components to get unusual structures or properties.Polyoxometalates （POMs） are excellent molecular acceptors which can form differentnature, size and shape of the organic and inorganic compounds with N, S, O etc organicelectronic donor through the molecular self-assembly. Polyoxometalate （POM） clusterswith unrivaled structural diversity offer interesting and exciting perspectives in manyimportant areas such as catalysis, photochromatic materials, non-linear opticalmaterials, electrochemistry, magnetism and medicine.Six new organic-inorganic hybrid compounds composed different polyanion andthe organic substrate aminopyridine/aminopyrimidine have been hydrothermallysynthesized and characterized by IR, UV-vis, FL, TG-DTA and single-crystal X-raydiffraction. And the effects of the compound oxidation catalytic activity of methanolwas characterized.1.Three new organic-inorganic hybrid compounds（2-C₅H₇N₂）₃·(SiMo₁₂O₄₀)·（C₄H₈N₄）_0.5·（C₅H₆N₂）₂·（H₂O）₂（1）、（3-C₅H₇N₂）₈·(SiMo₁₂O₄₀)₂·（C₅H₇N₃）₂·（H₈O₄）·（H₂O）₈（2）and （4-C₅H₇N₂）₆·(SiMo₁₂O₄₀)（3） composed the heteropolymolybdate α-H4SiMo₁₂O₄₀and the organic substrate2/3/4-aminopyridine have been hydrothermally synthesized.Crystal data of the title compound1: monoclinic, space group: P₂₁/c. Crystal data ofthe title compound2: tetragonal, space group: P4（2）/n. Crystal data of the titlecompound3: trigonal, space group: R-3. Compound1and2exhibit anthree-dimensional supramolecular network via hydrogen bond and π-π stackinginteractions. Compound2contains a tetramolecular water cluster which consists offour water molecules connected by hydrogen bonds. Compound3exhibits an extendedthree-dimensional supramolecular network via hydrogen bonding interactions. Thecompound1-3exhibit photoluminescent phenomena. The significant red-shift of thecompound1and2luminescence may be caused by the π-π stacking interactions in thestructure. Compound1and3are active for catalytic oxidation of methanol when theinitial concentration of methanol is2.75g m^-3in air and flow rate is10mL min^-1at150°C, corresponding to the elimination rate of methanol is87.7%and76.8%,respectively. The compound1-3exhibit blue fluorescence in the aqueous solution atroom temperature. Compound2has no catalytic activity that may attribute to theexistence of the tetramolecular water cluster ring structure. 2. Two new supramolecular structures organic-inorganic hybrid complexes（C₄H₇N₃）₂·(SiMo₁₂O₄₀)·（C₄H₅N₃）₂·（H₂O）₂（4） and （C₄H₇N₃）₂·(SiW₁₂O₄₀)·（C₄H₅N₃）₂·（H₂O）₂（5） constructed by polyanion and2-aminopyrimidine via hydrogen bond wereobtained by hydrothermal reaction and solution method. Crystal data of the titlecompound4: triclinic, space group: P-1. Crystal data of the title compound5:monoclinic, space group: C2. Compound4and5exhibit an three-dimensionalsupramolecular network via hydrogen bond. Compound5is active for catalyticoxidation of methanol when the initial concentration of methanol is5.37g m^-3in airand flow rate is5.0mL min^-1at90°C, corresponding to the elimination rate ofmethanol is53.09%.3. One new supramolecular structures organic-inorganic hybrid complex（C₄H₆N₃）₂·(PMo₁₈O₆₂)·（C₄H₇N₃）₂·（H₂O）₄（6） constructed by Dawson phosphomolybdate and2-aminopyrimidine via hydrogen bond were obtained by hydrothermal reaction andsolution method. Crystal data of the title compound5: orthorhombic, space group:Pnma, a=25.4728（17） A, b=20.3269（8）A, c=15.6810（7） A, α=90.0000°, β=90.0000°,γ=90.0000°, V=8119.4（7） A³, Z=4, R_int=0.0383, wR=0.2214, GoF=1.055. Compound6exhibits an extended two-dimensional layer structure via hydrogen bondinginteractions. Compound6is consisted by one-dimensional long-chain composed by[P₂Mo₁₈O₆₂]^6-and one-dimensional long-chain organic ligands arranged alternately toform a two-dimensional layer structure along the a-axis direction. There existmicropores structures along the b-axis direction. The micropores are consisted by six[P₂Mo₁₈O₆₂]^6-anion and the solvent-accessible volume of the unit cell was estimated,（PLATON program） to be1453.37A³, which is approximately17.9%of the unit-cellvolume （8119.4（7） A³）. Compound6forms a Z-shaped one-dimensional chainstructure along the c-axis direction. This compound6has excellent performance withreversible photochromic.Six new organic-inorganic hybrid complexes were synthesized which enrich thedatabase of crystallography and has good application prospect in eliminating gas phasecontaminants, fluorescent material and photosensitive material.