Synthesis and Characterization of Tetravalent Cerium Complexes with p-Tert-butylcalix[n]arenes (n=4, 6, 8)

Three Ce 4+ complexes Ce(p tert butylcalixarene)·(dmf) 4·H 2O (complex A), Ce(p tert butylcalixarene) 2·(dmf) 10 (complex B) and Ce(p tert butylcalixarene)·(dmf) 4 (complex C) were prepared from N,N dimethylforamide (dmf) solution of Ce(NO 3) 3. Their thermal stability, optical properties and coordination features were investigated with thermogravimetric and differential thermal analysis, ultraviolet and visible spectrophotometer, fluorescence spectrophotometer, infrared spectroscopy, and 1H NMR spectrometer. In the solvents of C 6H 6, 1,2 dichloroethane and dmf, complexes A and B can exhibit a ligand to metal charge transfer transition lying in ca. 20000 cm -1 in the electronic spectra. Complex A displays a dimeric structure in C 6D 6 solution. Ce 4+ ions in the complexes are coordinated by phenolic groups of the ligands, oxygen atoms of dmf molecules, and / or OH - ions.

Catalytic performance of cerium iron complex oxides for partial oxidation of methane to synthesis gas

The cerium iron complex oxides oxygen carrier was prepared by the co-precipitation method. The reactions between methane and lattice oxygen from the complex oxides were investigated in a fixed micro-reactor system. The reduced oxygen carder could be re-oxidized by air and its initial state could be restored. The characterizations of the oxygen carders were studied using XRD, O2-TPD, and H2-TPR. The results showed that the bulk lattice oxygen of CeO2-Fe2O3 was found to be suitable for the partial oxidation of methane to synthesis gas. There were two kinds of oxygen species on the oxygen carrier： the stronger oxygen species that was responsible for the complete oxidation of methane, and the weaker oxygen species （bulk lattice oxygen） that was responsible for the selective oxidation of methane to CO and H2 at a higher temperature. Then, the lost bulk lattice oxygen could be selectively supplemented by air re-oxidation at an appropriate reaction condition. CeFeO3 appeared on the oxygen carrier after 10 successive redox cycles, however, it was not bad for the selectivity of CO and H2.

Synthesis,Crystal Structure and Optical Properties of a Cerium(Ⅳ) Complex with Chelidamic Acid

A new cerium complex, （C7H8）[Ce（C7H3NO5）2（H2O）3]·2H2O or （C7Hs）[Ce（HChel）2· （H2O）3]·2H2O （1, H3Chel = 4-hydroxypyridine-2,6-dicarboxylic （chelidamic） acid）, has been prepared by the hydrothermal reaction, and its crystal structure was determined based on single-crystal diffraction data. Compound I crystallizes in monoclinic, space group P21/c with a = 12.4267（9）, b = 10.8195（7）, c = 19.5650（13）A, β = 92.898（3）°, V = 2627.2（3） A^3, Dc = 1.733 g/cm^3, Z = 4, Mr = 685.55, μ = 1.809 mm^-1, λ（MoKa） = 0.71073A and F（000） = 1372. The final R = 0.0455 and wR = 0.1984 for 5983 observed reflections with I 〉 2σ（I）, and R = 0.0490 and wR = 0.2053 for all data. Complex 1 contains one cerium ion, two chelidamic acid ligands, three coordinated water molecules, one discrete toluene molecule, and two discrete water molecules. The Ce（IV） ion is nine-coordinate with the coordination polyhedron made up of four oxygen atoms and two nitrogen atoms from two tridentate chelating chelidamic acid ligands, and three coordinated water molecules. A three-dimensional network is formed by the H-bonds. Moreover, optical properties are investigated and the results show that this complex has sharp optical absorption at 221,396 and 571 nm but no marked fluorescent emission.

Spectroscopy Study on Crystal Structure of Ce(NO_3)_3(phen)_2 and Interactions of Ce(NO_3)_3(phen)_2 with DNA

The absorption, fluorescence and Raman spectra of Ce(NO3)(3)(phen)(2) complex were assigned and the crystal structure of the complex was studied. Meanwhile the interactions between Cc (NO3)(3) (phen)(2) and DNA were studied by spectrum methods. As DNA was added, it is found that both the UV absorption bands of Ce(NO3)(3)(phen)(2) and the SERS bands of Ce(NO3)(3)(phen)(2) weaken evidently, while the fluorescence intensity of Ce(NO3)(3)(phen)(2) enhance dramatically. The complex compete against EB on the reaction with DNA. It is indicated by this spectrum methods that there are strong interactions between Ce(NO3)(3)(phen)(2) and DNA, and the bond mode is intercalation. The bond constant of the complex with DNA is determined to be 1.7 x 10(5).

Synthesis and Crystal Structure of Rare Earth Complex withCiprofloxacin

The complex of rare earth with ciprofloxacin has been synthesized and characterized by means of x-ray single crystal diffraction. The structure features of the complex are decribed.

Synthesis and Structure of a Polymeric Complex [Ce(bphsb)_2(NO_3)_3]_n

Polymeric cerium nitrate complex with 1,4 bis(phenylsulfinyl)butane (bphsb) [Ce(bphsb) 2(NO 3) 3] n (1) was synthesized and characterized. The crystal structure of the complex indicated that the ligand bphsb and cerium(Ⅲ) ion form a polymeric double bridge chain complex involving 18 membered macrometallocycles. Each cerium ion is coordinated by ten O atoms in a distorted 4,4 bicapped square antiprism. In the complex the disulfoxide ligand acts as bis monodentate O ligand bridging metal centers.

Crystal Structure of Quaternary Mixed Anion Complex of Labthanide [Ce(CH_3COO)_2(NO)_3(phen)]_2

[Ce(CH3COO)2(NO3) (phen)]2, Mr=1000. 84. The crystal is monoclinic, lattice type C-centered, space group C2/m, with a=15. 444 (6), b= 12. 273(5), c=12. 776(5) A, β= 131. 89(2)°, Z= 2, Dc= 1, 844 g/cm3, μ(MoKa)=25. 69 cm-1, F(000)=980. 00, V= 1802 (1 ) A, R=0.024, Rw=0. 032. Themolecule of the complex is a dimer with C2h symmetry and the molecular center lies onthe special position 2/m. The Ce(Ⅲ) ion is nine-coordianted to one bidentate nitrategroup, five oxygen atoms of acetates and two nitrogen atoms of 1, 10-phenanthroine(phen).

A novel catalyst of silicon cerium complex oxides for selective catalytic reduction of NO by NH_3

A series of CeO2/SiO2 and SixCe1–xO2 complex oxides supported on an activated Al2TiO5-TiO2-SiO2 complex phase (ATS) ceramics were prepared by step impregnation and co-impregnation methods, and characterized by N2-BET, XRD, SEM and NH3-TPD techniques. The effects of reaction temperature, CeO2/SiO2 loadings and Si/Ce molar ratio on the granular catalysts for NO selective catalytic reduction with ammonia (NH3-SCR) were studied. Results indicated that both CeO2/SiO2/ATS and CeO2/ATS catalysts showed the same ac...

Synthesis of monodispersed nanosized CeO_2 by hydrolysis of the cerium complex precursor

A cerium-triethanolamine complex was obtained by the reaction of cerium(III) nitrate and triethanolamine in ethanol solution. Spontaneous oxidation of cerium(III) to cerium(IV) by oxygen occurred during the reaction. The complex was crystalline and soluble in water. Nanosized ceria (CeO2) particles could be prepared via hydrolysis of the complex in aqueous solution, and the extent of agglomeration of particles increased with the increase in temperature for hydrolysis. Under the low temperature of 25 oC, mon...