A novel efficient approach to heteronuclear triple-decker complexes of rare earth elements with phthalocyanines

A novel approach to heteroleptic heteronuclear rare earth metal(III) trisphthalocyaninates was proposed with the complexes [(15C5)₄Pc]M*[(15C5)₄Pc]M(Pc) as examples (15C5 is 15-crown-5, Pc^2? is the phthalocyaninate dianion, and M* ?? M = Yb and Y). Unsubstituted lanthanum bisphthalocyaninate, La(Pc)₂, was used for the first time as a Pc^2? donor in the synthesis of such complexes. This substantially increased the yields of the target heteronuclear complexes over the previous literature data.     

Heteroleptic rare earth double-decker complexes with naphthalocyaninato and phthalocyaninato ligands. General synthesis, spectroscopic, and electrochemical characteristics

A novel one-pot procedure starting from the corresponding M(acac)3 x nH2O, metal-free phthalocyanine H2Pc', and naphthalonitrile in the presence of DBU in n-octanol has been developed to prepare heteroleptic (naphthalocyaninato)(phthalocyaninato) rare earth double-decker complexes. A series of six sandwich compounds with different naphthalocyaninato ligands, phthalocyaninato ligands, and central rare earth metals, namely, Sm[Nc(tBu)4](Pc) [Nc(tBu)4 = 3(4),12(13),21(22),30(31)-tetra(tert-butyl)naphthalocyaninato; Pc = unsubstituted phthalocyaninato] (1), Sm(Nc)(Pc') [Pc' = Pc(OC5H11)4, Pc(OC8H17)8; Nc = 2,3-naphthalocyaninato; Pc(OC5H11)4 = 2(3),9(10),16(17),24(25)-tetrakis(3-pentyloxy)phthalocyaninato; Pc(OC8H17)8 = 2,3,9,10,16,17,24,25-octakis(octyloxy)phthalocyaninato] (2, 3), and M(Nc)[Pc(alpha-OC5H11)4] [M = Sm, Eu, Y; Pc(alpha-OC5H11)4 = 1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninato] (4-6), have been isolated in good yields from this one-pot procedure demonstrating the generality of this synthetic pathway. In addition to spectroscopic analyses, the electrochemistry of these novel compounds has also been studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods.     

Studies on rare earth trisoxalatoferrate(III) and rare earth ortho ferrite

The preparation and characterization of LaFe(C₂O₄)₃·9H₂O is described but the trisoxalatoferrate(III) of other lanthanides could not be isolated. However, the lanthanum ion in LaFe(C₂O₄)₃·9H₂O can be partly replaced by other lanthanide ions, e.g. with Nd(III) doping to the extent of 0.33 mole fraction of the latter has been accomplished. In the compounds La_1−xNd_xFe(C₂O₄)₃·9H₂O a stron magnetic interaction between Fe³⁺ and Nd³⁺ is observed. From a comparison of the IR and diffuse reflectance spectra and the X-ray diffraction data it is shown that K₃Fe(C₂O₄)₃·9H₂O and LaFe(C₂O₄)₃·9H₂O are not isostructural. Thermal analysis (combined TG, DTA and DTG) of LaFe(C₂O₄)₃·9H₂O establishes that this compound is precursor of LaFeO₃. The LaFeO₃ obtained, has been characterized by its X-ray diffraction pattern, measurement of its magnetic moment, and by its electronic and IR spectra. The thermal behavior of physical mixtures of La₂(C₂O₄)₃·10H₂O and Fe₂(C₂O₄)₃·5H₂O and La₂(C₂O₄)₃·10H₂O and Fe(C₂O₄)·2H₂O has also been investigated and the products of thermal analysis at ∼1000°C in air found to be a mixture of La₂O₃ and αFe₂O₃.     

Studies on rare earth trisoxalatochromates (III), rare earth chromates (V) and rare earth chromites (III)

Rare earth trisoxalatochromates (III), LnCr(C₂O₄)₃·nH₂O (n = 9 for La, and n = 8 for Ce, Pr and Nd) have been isolated and characterized by a number of physicochemical studies. These compounds (except for Ce) serve as precursors for the rare earth chromates (V) and chromites (III). LnCrO₄ may be obtained by heating LnCr(C₂O₄)₃·nH₂O at 520°C for 4 hr and LnCrO₃ at 900°C for a similar period. CeCr(C₂O₄)₃. 8H₂O decomposes to a mixture of CeO₂ and Cr₂O₃. The EPR spectra of LaCrO₄ are consistent with a tetrahedral geometry of the CrO₄ group. Although the unit cell of LaCrO₄ is monoclinic and of NdCrO₄ is tetragonal, compounds of composition La_1−xNd_xCrO₄ show the presence of only monoclinic phase for x up to 0.23. The electronic spectra of LnCrO₃ are compatible with the perovskite structure of these compounds.     

Studies of "pinwheel-like" bis[1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninato] rare earth(III) double-decker complexes

Homoleptic bis(phthalocyaninato) rare-earth double-deckers complexes [M(III)[Pc(alpha-OC5H11)4]2] (M = Eu, Y, Lu; Pc(alpha-OC5H11)4 = 1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninate) have been prepared by treating the metal-free phthalocyanine H2Pc(alpha-OC5H11)4 with the corresponding M(acac)3.nH2O (acac = acetylacetonate) in refluxing n-octanol. Due to the C4h symmetry of the Pc(alpha-OC5H11)4 ligand and the double-decker structure, all the reactions give a mixture of two stereoisomers with C4h and D4 symmetry. The former isomer, which is a major product, can be partially separated by recrystallization due to its higher crystallinity. The molecular structure of the major isomer of the Y analogue has been determined by single-crystal X-ray diffraction analysis. The metal center is eight-coordinate bound to the isoindole nitrogen atoms of the two phthalocyaninato ligands, forming a distorted square antiprism. Such an arrangement leads to an interesting pinwheel structure when viewed along the C4 axis, which assumes a very unusual S8 symmetry. The major isomers of all these double-deckers have also been characterized with a wide range of spectroscopic methods. A systematic investigation of their electronic absorption and electrochemical data reveals that the pi-pi interaction between the two Pc(alpha-OC5H11)4 rings is weaker than that for the corresponding unsubstituted or beta-substituted bis(phthalocyaninato) analogues.     

Studies on rare earth 1,3-diketonates

The chelates of various rare earths with acetylacetone, benzoylacetone, dibenzoylmethane, 2-thenoyltrifluoroacetone and dithenoylmethane were prepared and some of their physical properties noted. The ultraviolet absorption spectra in various non-aqueous solvents were measured. Absorption measurements in the visible region showed alterations in absorption intensities and resolution in some of the principal bands, depending on the solvent. The infrared spectra were measured and compared with literature data.     

Concentration of all rare earth impurities of cerium sub-group rare earth matrices

The separability of all rare earth impurities from cerium sub-group matrices was investigated. It was found that anion exchange chromatography carried out with aqueous methanol solutions of nitrates provides a useful method for the concentration of all rare earth impurities in neodymium and gadolinium matrices. The concentrate of the impurities can be processed further as required by the method chosen for their analytical determination.     

辉光放电质谱法测定稀土矿中的15种稀土元素

利用高纯铜粉与稀土矿石粉末均匀混合压片制样.混合15种高纯稀土氧化物制样建立标准工作曲线,校正15种稀土元素相对灵敏度因子,再进行定量分析.结果 表明,稀土元素工作曲线的线性方程相关系数R2均大于0.996,相对标准偏差(RSD)小于5％,满足定量分析要求.测定结果与电感耦合等离子体质谱法(ICP-MS)和电感耦合等离...     

Sandwich-type mixed (phthalocyaninato)(porphyrinato) rare earth double-decker complexes with decreased molecular symmetry of Cs: single crystal structure and self-assembled nano-structure

Two novel sandwich-type mixed (phthalocyaninato)(porphyrinato) rare earth double-decker complexes with decreased molecular symmetry of Cs M(Pc)[D(NHC(8)H(17))(2)PP] [M = Eu, Lu; Pc = unsubstituted phthalocyaninate; D(NHC(8)H(17))(2)PP = 5,10-di(phenyl)-15,20-di(4-octylamino-phenyl)porphyrinate] (1, 2) have been designed, prepared, and characterized. The single crystal and molecular structure of the Eu analogue has been determined by X-ray diffraction analysis, revealing the head-to-tail supramolecular chains formed from closely bound double-decker molecules depending on the N-H-N hydrogen bonds between one octyl-substituted amidocyanogen group attached at the p-position of meso-attached phenyl group of the porphyrin ligand in the mixed ring double-decker molecule and one aza-nitrogen atom of the phthalocyanine ring in the neighboring double-decker molecule in a zigzag form. Their self-assembled nano-structures have been investigated by transmission electronic microscopy (TEM) and scanning electronic microscopy (SEM). Intermolecular H-N-H hydrogen bonding interaction leads to the formation of nano-structures with fusiform morphology with 220-250 nm average width and about 10 μm length for 1 and 300 nm width and 3-5 μm length for 2, respectively, revealing the effect of molecular size in the direction perpendicular to the tetrapyrrole ring on the dimensions of self-assembled nano-structures.     

Nanocomposites based on opal matrices and silica sols doped with rare earth compounds

Ordered 3D composites based on opal matrices and silica sols doped with rare earth elements have been prepared using colloidal chemistry methods. A uniform distribution of rare earth elements (which is important for avoiding luminescence concentration quenching) was achieved by means of repeated filling of the opal matrix interstitial space with silica sols doped with salts or oxides of rare earth elements. Trace amounts (10–30 ppm) of europium in a composite were shown to strongly affect optical properties of the material.     

New coordination catalysts based on rare earth compounds for polymerization of 1-octene

The study of rare earth coordination catalysts for polymerization of 1-octene has been successfully carried out for the first time. Some features and kinetic behavior of polymerization of 1-octene by Nd(naph)₃–AIEt₃ catalyst system in tetrachloro-methane are described. The overall polymerization activation energy E_a measured was 74.5 kJ/mol and the rate equation could be expressed as R_p = k_p [Nd] [M] (k_p = 3.21 × 10^?3 L/mol s, at 50°C). The catalytic activity of various rare earth elements in Ln (naph)₃ and ligands in NdL₃ for the polymerization was compared. A 1-octene oligomer with double bonds was obtained. It is either a white or pale yellow waxy semi-solid. Its number-average molecular weight is about 10³ and the molecular weight distribution is less than 2.     

Titration of binary mixtures of rare earth metals based on magnetic susceptibility measurements

Gouy balance weighings are used to monitor precipitation titrations of rare earth ions with standardized oxalate solutions. A procedure is described for the analysis of binary mixtures of these compounds. The accuracy of the determinations at the millimolar level depends on the magnetic moments of the components involved but is generally better than ±4%.     

稀土酞菁配合物的XPS研究

本文合成了一系列稀土单酞菁配合物Lnpc(0AC)2,和Lnpccl(Ln=Tb,Ho, Tm, Lu,Pc为酞菁根, OAC为乙酸根)并用XPS较详细地研究了它们的电子结构, 讨论了它们的化学键性质和组成。     

Constructing sandwich-type rare Earth double-decker complexes with N-confused porphyrinato and phthalocyaninato ligands

Reaction of the half-sandwich complexes M(III)(Pc)(acac) (M = La, Eu, Y, Lu; Pc = phthalocyaninate; acac = acetylacetonate) with the metal-free N-confused 5,10,15,20-tetrakis[(4-tert-butyl)phenyl]porphyrin (H(2)NTBPP) or its N2-position methylated analogue H(CH(3))NTBPP in refluxing 1,2,4-trichlorobenzene (TCB) led to the isolation of M(III)(Pc)(HNTBPP) (M = La, Eu, Y, Lu) or Y(III)(Pc)[(CH(3))NTBPP] in 8-15% yield. These represent the first examples of sandwich-type rare earth complexes with N-confused porphyrinato ligands. The complexes were characterized with various spectroscopic methods and elemental analysis. The molecular structures of four of these double-decker complexes were also determined by single-crystal X-ray diffraction analysis. In each of these complexes, the metal center is octa-coordinated by four isoindole nitrogen atoms of the Pc ligand, three pyrrole nitrogen atoms, and the inverted pyrrole carbon atom of the HNTBPP or (CH(3))NTBPP ligand, forming a distorted coordination square antiprism. For Eu(III)(Pc)(HNTBPP), the two macrocyclic rings are further bound to a CH(3)OH molecule through two hydrogen bonds formed between the hydroxyl group of CH(3)OH and an aza nitrogen atom of the Pc ring or the inverted pyrrole nitrogen atom of the HNTBPP ring, respectively. The location of the acidic proton at the inverted pyrrole nitrogen atom (N2) of the protonated double-deckers was revealed by (1)H NMR spectroscopy.     

Distribution characteristics of rare earth elements in plants from a rare earth ore area

The contents of eight rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) in various plant species taken from a rare earth ore area were determined by instrumental neutron activation analysis. For a given plant, the REE patterns in root, leaf and host soil are different from each other. The REE distribution characteristics in roots of various species are very similar and resemble those in the surface water. The results of this study suggest that there is no significant fractionation between the REEs during their uptake by the plant roots from soil solution. However, the variation of the relative abundance of individual REE occurs in the process of transportation and deposition of REEs in plants.     

Synthesis of rare earth monoxides

The standard Gibbs energy changes for the formation of an ionic or metallic monoxide from rare earth metal and sesquioxide have been calculated. Under high pressures ionic ytterbium monoxide and lighter rare earth metallic monoxides should be obtained, which is confirmed by experiments in a belt-type apparatus in the range 15–80 kbar and 500-1200°C. For Ln =La, Ce, Pr, Nd, Sm, a face-centered cubic compound is obtained from each reaction. The cell parameters are respectively 5.144, 5.089, 5.031, 4.994, and 4.943 ± 0.005A?. The compounds appear golden yellow with a metallic luster. From chemical analyses and cell parameter consideration it is concluded that these compounds are the rare earth monoxides. For Ln =Gd, Dy, Tm, no reaction is observed at 50 kbar and 1000°C. The rare earth monoxides show a variety of properties: LaO, CeO, PrO, and NdO are metallic with the rare earth in the trivalent state; EuO and YbO are semiconductors with the rare earth in the divalent state; SmO is metallic with samarium in an intermediate valence state close to 3.     

Thin-film transistors based on Langmuir-Blodgett films of heteroleptic bis(phthalocyaninato) rare earth complexes

An ordered molecular assembly of heteroleptic bis(phthalocyaninato) rare earth complexes M(Pc)[Pc(OC8H17)8] [M = Tb, Lu; H2Pc = phthalocyanine; H2Pc(OC8H17)8 = 2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyanine] has been fabricated by the Langmuir-Blodgett (LB) technique and characterized by surface pressure-area isotherms, electronic absorption and polarized electronic absorption spectroscopy, low-angle X-ray diffraction, and atomic force microscopy. The molecular ordering in the LB multilayer film on SiO2 substrate was made into a p-channel field effect transistor (FET), which was generally operated in the enhanced mode. The energy levels of the highest occupied molecular orbital and the lowest unoccupied molecular orbital as well as the energy band diagram can be deduced from the electrochemical measurement results. The charge mobilities of Tb(Pc)[Pc(OC8H17)8] and Lu(Pc)[Pc(OC8H17)8] were calculated to be about 6.4 x 10(-4) and 1.7 x 10(-3) cm2 V(-1) s(-1), respectively.     

Heats of the tetragonal-cubic transformation in rare earth dicarbides and mixed rare earth dicarbide solid solutions

Solid solutions of two different rare earth dicarbides have been prepared and the relation between their compositions and heats of the tetragonal to cubic transformation in them has been discussed.Pure rare earth dicarbides showed a heat of transformation of about 4 kcal/mole while the heat for solid solution changed with its composition, in the case of La_0·47Gd_0·53C_2′ was as low as 0·8 kcal/mole. Furthermore, some solid solutions, for instance La_0·31Dy_0·69C_2′, transformed from b.c.t. to f.c.c. without showing any heat.