Study of FT-Raman Spectroscopy on the Effects of Lanthanide Ions and Their Complexes on the Fluidity of Dipalmitoylphosphatidylethanolamine Bilayer

The effects of lanthanide ions and their complexes of citrate and DTPA ligands on the fluidity of dipalmitoylphosphatidylethanolamine (DPPE) bilayers have been studied by FT-Raman spectroscopy. the results show that lanthanide ions of lower concentrationn decrease the fluidity of acyl chains of DPPE bilayers and change the conformation of C C-C backbone from gauche to the trans lanthanide ions of higher concentration, however, increase the fluidity of acyl chains and increase the gauche population of C-C-C backbone. Lanthanide complex of citrate have no effect on the fluidity of acyl chains of DPPE bilayers in the region of experimental concentration, but La-DTPA complex increase slightly the fluidity of acyl chains. the results also indicated that lanthanide ion of lower concentration changed the lattice packing of hydrocarbon chains from hexagonal form to orthorhombic form, but it is still in hexagonal or distorted hexagonal lattice cell in the gel state in the presence of metal ions and lanthanide complexes of higher concentration

THE SYNTHESIS AND PHYSICAL-PROPERTIES OF THE NEW LAYERED LANTHANIDE ALKALINE-EARTH COBALT OXIDES [LN2MCO2O7 (LN=SM,GD M=SR,BA)]

Three new oxides Sm2SrCo2O7, Sm2BaCo2O7 and Gd2SrCo2O7 have been successfully synthesized by a solid state reaction method.The X - Ray diffraction spectra show that they are all isostructural with Sr8Ti 2O7, Ln2SrCo2O7(Ln=Sm, Gd) crystallized in the tetra

EFFECT OF LANTHANIDE IONS ON THE PHASE-BEHAVIOR OF DIPALMITOYLPHOSPHATIDYLCHOLINE MULTILAMELLAR LIPOSOMES

The effect of lanthanide ions (Ln(3+)) and their coordination compounds of diethylenetriamine pentaacetic acid (DTPA) on the phase behavior of dipalmitoylphosphatidycholine (DPPC) multilamellar liposomes has been studied by differential scanning calorimet

SYNTHESIS AND CHARACTERIZATION OF POLYMER-SUPPORTED LANTHANIDE COMPLEXES AND BUTADIENE POLYMERIZATION BASED ON THEM

Poly(styrene-acrylic acid)-lanthanide (Ln.PSAA) and poly(ethylene-acrylic acid)-neodymium (NdPEAA) complexes have been prepared and characterized. The infrared and X-ray photoelectron spectra indicate that the lanthanide complexes possess the bidentate carboxylate structure Ln-O-C(R)-O (see structure B in text). The catalytic behavior of the complexes has been described. The catalytic activities of Nd.PSAA and Nd.PEAA are much greater than that of the corresponding low molecular weight catalyst for butadiene polymerization. The activities of various individual lanthanide elements are quite different from one another. Neodymium shows the highest activity. Europium, samarium and the heavy elements exhibit very low or no activities. The cis-1,4 content of the polybutadiene obtained is not affected by different lanthanide elements in the series. The complex with the intermediate content of the functional group has a higher activity than the others. The polymer-supported lanthanide complexes having different constitutions have different catalytic activities. When the molar ratio of lanthanide to the functional group is ca. 0.2, the activity of the complex is in the optimum state. The activity is influenced by the dispersion of the lanthanide metal immobilized on the polymer chain. Catalytic activity can be improved by adding other metals to the catalyst system.

INFRARED-SPECTRA OF DIMETHYLPHOSPHATE LANTHANIDE COMPLEXES

The infrared spectra of the crystalline solid samples of rare earth(III) dimethylphosphates Ln(DMP)3 (Ln = La, Ce, Nd) in the range 4000-100 cm-1 are discussed. It is shown that the spectra may be treated by dividing Ln(DMP)3 into two parts, an OP(OCH3)2O bridge and a LnO6 distortion octahedron. The absorption bands above 500 cm-1 may be clearly assigned. However, vibrational assignments in the far-infrared region are tentative.

SYNTHESIS AND CHARACTERIZATION OF HETEROPOLY BLUES OF BIS-2/17 MOLYBDOPHOSPHATE COMPLEXES WITH LANTHANIDE

Eight heteropoly blues of bis-2:17 molybdophosphate complexes with Lathanide, i.e., K17H2[Ln(P2Mo17O61)2] . nH2O and K17H4[Ln(P2Mo17O61)2] . nH2O were synthesized and characterized by elemental analyses potentiometric titration, IR, UV, polarography, cyclic voltammetry, X-ray photoelectron spectra X-ray powder diffraction, thermal analyses and ESR. Experimental results show that the properties of these series of heteropoly blues are different from those of their oxidized form, but no great changes in their structures were observed. The ligand P2Mo17O6110- remains alpha2-isomer's configuration.

SYNTHESES AND X-RAY STRUCTURES OF BIS(T-BUTYLCYCLOPENTADIENYL)LANTHANIDE CHLORIDE COMPLEXES [(BU(T)CP)2LNCL]2 (LN = PR, GD, ER)

Reaction of lanthanide trichlorides with two equivalents of sodium t-butylcyclopentadienide in THF gave rise to the bis(t-butylcyclopentadienyl)lanthanide chloride complexes [(Bu(t)Cp)2LnCl]2 (Ln = Pr, Gd, Er), which were characterized by elemental analysis, IR and H-1 NMR spectroscopy. In addition, the crystal structures of [(ButCp)2PrCl]2 (1) and [(ButCp)2GdCl]2 (2) were determined by single crystal X-ray diffraction at room temperature. The coordination number for Pr3+ and Gd3+ is 8 and the bond lengths Pr-Cl and Gd-Cl are 2.864(2) and 2.771(3) angstrom, respectively. The structural studies showed the complexes to have C2h symmetry.

DIELS-ALDER REACTIONS CATALYZED BY LANTHANIDE CHLORIDES

Lanthanide chlorides have been found to catalyze the Diels-Alder synthesis of 2-butoxy-3, 4-dihydro-2H-pyran and several norbornene derivatives under mild conditions. In particular, the heavier lanthanide chlorides are very active catalysts for some (4 + 2) cycloaddition reactions. The catalyst activities and selectivities generally increase with increasing atomic number of the rare earth elements.

STUDY ON BONDING AND 4F ORBITAL EFFECT OF LANTHANIDE COMPOUNDS

The bonding and the 4f orbital effect of lanthanide elements at different valence state in their compounds have been studied by INDO method in this paper. The results obtained show that the bonding of lanthanide compounds is affected by many factors, such as valence state, ionic radius, ligand, coordinate number, space configuration etc. The strength of bonds composed of different ligands with lanthanide is distinctly different. The covalence of Ln-L bonds of lanthanide ions at high valence state in their compounds is larger than that at low valence state, The covalency at low coordinate number is larger than that at high coordinate number. Some lanthanide compounds with special configuration, besides sigma-bond, can form p(pi)-d(pi) dative bond with much overlap, which makes the Ln-L bond increase markedly. The effect of 4f orbitals on bonding is far less than that of 5d orbitals. The Ln 4f orbitals at 3 or 2 valence state may be considered to be essentially localized, while the contribution of 4f orbitals on bonding in 4 valent cerium compounds increases obviously, up to 1%.

SYNTHESIS AND X-RAY CRYSTAL-STRUCTURE OF [EU(ETA-6-C6ME6)(ALCL4)2]4 - THE 1ST CYCLOTETRAMERIC LANTHANIDE(II) COMPLEX WITH A NEUTRAL PI-LIGAND

The reaction of EuCl3, AlCl3 and C6Me6 in toluene gives the Eu(II) complex [Eu(eta-6-C6Me6)(AlCl4)2]4; X-ray crystal determination shows the molecule to be a cyclotetramer, in which the four Eu(C6Me6)AlCl4 units are connected via four groups of eta-2-AlCl4.

C-13 AND H-1 NMR STUDIES OF SOLUTION STRUCTURE OF LANTHANIDE COMPLEX WITH GLYCYL-GLYCINE

C-13 and H-1 NMR technique was used to study the interaction of Gly-Gly with heavy lanthanide cations Dy3+, Ho3+, Er3+, Tm3+ and Yb3+ in aqueous solution. The stability constants for the 1:1 and 1:2 complexes of Gly-Gly with Ho3+ and Yb3+ were determined from the titration curves of chemical shift versus concentration ratio of lanthanide to Gly-Gly. The solution structure of the Ln-Gly-Gly complex was analyzed based upon the C-13 and H-1 lanthanide induced shifts and the results show that in the complex Gly Gly is coordinated to the lanthanide ion through the carboxyl oxygens with the backbone of the ligand in an extended state.

SYNTHESIS AND CRYSTAL-STRUCTURE OF A NEW LANTHANIDE CYCLOOCTATETRAENE COMPLEX (ETA-8-C8H8)ER(MU-ETA-8-C8H8)K(MU-ETA-8-C8H8)ER(MU-ETA-8-C8H8)K(THF)4

The tetranuclear nearly-linear complex (eta-8-C8H8)Er(mu-eta-8-C8H8)K(mu-eta-8-C8H8)Er(mu-eta-8-C8H8)K(THF)4 (THF = tetrahydrofuran) is first synthesised by the reaction of benzylcyclopentadienyl erbium dichloride (PhCH2C5H4)ErCl2.3THF with cyclooctatetraenyl potassium K2C8H8 in 1:1 molar ratio in THF; a single crystal X-ray study has shown that the complex has the tetralayer-sandwich structure and that the adjacent Er3+ and K+ ions are bridged by eta-8-cyclooctatetraenyl group.

SYNTHESIS OF ALKALI-METAL HYDRIDES USING LANTHANIDE TRICHLORIDE-NAPHTHALENE AS CATALYST UNDER MILD CONDITIONS

The hydrogenation of alkali metals using lanthanide trichloride and naphthalene as catalyst has been studied. LnCl3(Ln = La, Nd, Sm, Dy, Yb) and naphthalene can catalyze the hydrogenation of sodium under atmospheric pressure and 40-degrees-C to form sodium hydride. The activities of lanthanide trichlorides are in the following order: LaCl3 > NdCl3 > SmCl3 > DyCl3 > YbCl3. Although lithium proceeds in the same catalytic reaction, the kinetic curve of the lithium hydrogenation is different from that of sodium. Lanthanide trichlorides display no catalytic effect on the hydrogenation of potassium in presence of naphthalene. The mechanism of this reaction has been studied and it is suggested that the anion-radical of alkali metal naphthalene complexes may be the intermediate for the hydrogenation of alkali metals and the function of LnCl3 is to catalyze the hydrogenation of the intermediate. The products are porous solids with high specific surface area (83 m2/g for NaH) and pyrophoric in air. They are far more active than the commercial alkali metal hydrides. The combination of these hydrides with some transition metal complexes exhibits high catalytic activity for the hydrogenation of olefins.