Study On Crystal Structure And Properties Of Keggin-type Phosphormolybdate, Arsenicmolybdate Polyoxometalates Organic-inorganic Hybrid Supramolecular Compounds

Six Keggin-type phosphormolybdate, arsenicmolybdate polyoxometalatesanion organic-inorganic hybrid supramolecular compounds weresynthsised by hydrothermal methods at moderate temperature and all thecrystal structures were abtained by X-crystal diffraction. They werecharacterized by IR and TG-DTA.Two new inorganic-organic hybrid supramolecular compound 1 andcompound 2 were synthesised with Keggin-type phosphomolybdate anion asthe main body and 4-aminopyridine or 3-aminopyridine as a ligand. Thecompound (4-C₅H₇N₂)₃(PMo₁₂O₄₀)·(4-C₅H₆N₂)·H₂O (1) was consisted ofphosphormolybdate anion and 4-aminopyridine was crystallized in themonoclinic, space group: C2/c, a=11.7094(4)(A|°),α=90°, b=25.7946(9)(A|°),β=97.2050°, c=16.6748(6)(A|°),γ=90°, V= 4996.7(3)(A|°)³, Z=4, R_gt(F)=0.0456,ωR_ref(F²)=0.142.The compound (3-C₅H₇N₂)₃(PMo₁₂O₄₀)·4(3-C5H6N2)·6H₂O(2) consisted of phosphormolybdate and 3-aminopyridine was crystallizedin the tetragonal, space group: P42/n, a=14.2864(2)(A|°),α=90°, b=14.2864(A|°),β=90°, c=29.0414(8)(A|°),γ=90°, V=5927.4(2)(A|°)³, Z=4, R_gt(F)=0.0575,ωR_ref(F²)=0.1633. Both of compound 1 and compound 2 were formedinfinite three-dimensional framework via lots of hydrogen-bonds.Two new inorganic-organic hybrid supramolecular compound 3 andcompound 4 were synthesised with Keggin-type phosphomolybdate anion asthe main body and 4-picoline or 3-picoline as a ligand. The compound(4-C₆H₈N)₃(PMo₁₂O₄₀) (3) was consisted of phosphormolybdate and4-picoline was crystallized in the monoclinic, space group: P2(1)/c, a =19.7004(3)(A|°),α= 90°, b = 14.0785(2)(A|°),β= 91.3590(10)°, c = 33.0209(5)(A|°),γ= 90°, V= 9155.8(2)(A|°)³, Z=8, R_gt(F)= 0.0350,ωR_ref(F²)= 0.0730. Thecompound (3-C₆H₈N)₄(PMo₁₂O₄₀)·H₂O(4) consisted of phosphormolybdateand 3-picoline was crystallized in the monoclinic, space group: C2/c, a =19.4997(4)(A|°),α= 90°, b = 12.5836(3)(A|°),β= 109.5730(10)°, c = 22.5405(5)(A|°),γ= 90°, V= 5211.3(2)(A|°)³, Z=4, R_gt(F)= 0.0698,ωR_ref(F²)= 0.1849. Bothof compound 3 and compound 4 were formed infinite one-dimensional chainvia lots of hydrogen-bonds.Two new inorganic-organic hybrid supramolecular compound 5 andcompound 6 were synthesised with Keggin-type phosphomolybdate anion or arsenicmolybdate anion as the main body and benzimidazole as a ligand.The compound (C₇H₇N₂)₄(PMo₁₂O₄₀)·2H₂O (5) consisted of phosphormolybdateand benzimidazole was crystallized in the triclinic, space group:P-1, a=9.8405(7)(A|°),α=70.494(5)°, b=11.3588(7)(A|°),β=82.285(5)°,c=13.8561(10)(A|°),γ=71.161(6)°, V=1381.08(16)(A|°)³, Z=1, R_gt(F)=0.0631,ωR_ref(F²)=0.1392. The compound (C₇H₇N₂)₃(AsMo₁₂O₄₀)·2C₇H₆N₂·3H₂O (6)consisted of arsenicmolybdate and benzimidazole was crystallized in thetriclinic, space group: P-1, a = 12.3353(4)(A|°),α= 95.6630(10)°, b =13.2649(4)(A|°),β= 100.1720(10)°, c = 20.2878(6)(A|°),γ= 99.3940(10)°, V=3195.72(17)(A|°)³, Z=2, R_gt(F)= 0.0329,ωR_ref(F²)= 0.1080. Both of compound5 and compound 6 were formed infinite one-dimensional chain via lots ofhydrogen-bonds and weakπ-πstacking action.The results indicate that they all contain Keggin structure heteropolyacid anion, some of the organic ligand protonated as the counter cation werepresent in these compounds, some organic molecules and water moleculesnot protonated were also contained in some of these compounds. In thispaper, catalytic reduction of acetone as a probe was researched to exploratethe catalytic properties of these compounds, the stage results showed thatcomplound 3 and compound 5 have some catalytic activity, further researchis still in progress.