Catalytic hydrolysis of phosphate diester （BNPP） and plasmid DNA by mononuclear macrocyclic polyamine metal complexes

The activities of the catalytic hydrolysis of phosphate diester(BNPP)[bis(p-nitrophenyl)phosphate diester]and plasmid DNA (pUC18)by mononuclear macrocyclic polyamine metal complexes have been investigated in this paper.The results showed that the highest activity in hydrolysis of BNPP was obtained with 1e-Zn(Ⅱ)complex(composed of lipophilic group)as catalyst.The hydrolysis rate enhancement is up to 3.64×10~4 fold.These metal complexes could effectively promote the cleavage of plasmid DNA(pUC18)at physiol...     

Synthesis, characterization and reactivity of heteroleptic rare earth metal bis(phenolate) complexes

The synthesis, characterization and reactivity of heteroleptic rare earth metal complexes supported by the carbon-bridged bis(phenolate) ligand 2,2'-methylene-bis(6-tert-butyl-4-methyl-phenoxo) (MBMP(2-)) are described. Reaction of (C(5)H(5))(3)Ln(THF) with MBMPH(2) in a 1 : 1.5 molar ratio in THF at 50 degrees C produced the heteroleptic rare earth metal bis(phenolate) complexes (C(5)H(5))Ln(MBMP)(THF)(n) (Ln = La, n = 3 (); Ln = Yb (), Y (), n = 2) in nearly quantitative yields. The residual C(5)H(5)(-) groups in complexes to can be substituted by the bridged bis(phenolate) ligands at elevated temperature to give the neutral rare earth metal bis(phenolate) complexes, and the ionic radii have a profound effect on the structures of the final products. Complex reacted with MBMPH(2) in a 1 : 0.5 molar ratio in toluene at 80 degrees C to produce a dinuclear complex (MBMP)La(THF)(mu-MBMP)(2)La(THF)(2) () in good isolated yield; whereas complexes and reacted with MBMPH(2) under the same conditions to give (MBMP)Ln(MBMPH)(THF)(2) (Ln = Yb (), Y ()) as the final products, in which one hydroxyl group of the phenol is coordinated to the rare earth metal in a neutral fashion. The reactivity of complexes and with some metal alkyls was explored. Reaction of complex with 1 equiv. of AlEt(3) in toluene at room temperature afforded unexpected ligand redistributed products, and a discrete ion pair ytterbium complex [(MBMP)Yb(THF)(2)(DME)][(MBMP)(2)Yb(THF)(2)] () was isolated in moderate yield. Furthermore, reaction of complex with 1 equiv. of ZnEt(2) in toluene gave a ligand redistributed complex [(mu-MBMP)Zn(THF)](2) () in reasonable isolated yield. Similar reaction of complex with ZnEt(2) also afforded complex ; whereas the reaction of complex with 1 equiv. of n-BuLi in THF afforded the heterodimetallic complex [(THF)Yb(MBMP)(2)Li(THF)(2)] (). All of these complexes were well characterized by elemental analyses, IR spectra, and single-crystal structure determination, in the cases of complexes , and -.     

Synthesis and structural characterisation of novel linked bis(beta-diketiminato) rare earth metal complexes

Rare earth metal complexes based on novel linked bis(beta-diketiminato) ligands have been prepared via amine elimination and their structural characterisation revealed that the linker unit has significant influence on the geometry and coordination mode of the ancillary ligand.     

Trinuclear rare earth metal complexes based on 1,3,5-triamino-1,3,5-trideoxy-cis inositol as catalysts for the hydrolysis of phosphodiesters

Trinuclear rare-earth metal complexes [M?(taciH??)?](3+) (M = La(3+), Y(3+)), based on a rigid polyamino-polyalcohol ligand 1,3,5-triamino-1,3,5-trideoxy-cis-inositol (taci), are proven to be efficient catalysts for the hydrolysis of 2-hydroxypropyl-4-nitrophenyl phophate (HPNP), a commonly used RNA model system.     

Selectivity of glassy type mixed zirconium-titanium phosphate toward rare earth metal ions

The selectivity of glass type mixed Zr+Ti phosphates with various Ti contents has been investigated toward rare earth metal ions. The k_d values were determined by radiotracer technique both in HCl and HNO₃ solutions of various concentrations. At room temperature and at pH=4 the following selectivity orders were found: Yb>TmEu>Sm>La (HCl) and Eu>La>Sm>Yb>Tm (HNO₃).     

Poly(propylene imine) dendrimer complexes of Cu(II), Zn(II), and Co(III) as catalysts of hydrolysis of p-nitrophenyl diphenyl phosphate

Poly(propylene imine) dendrimers having 8, 32, and 64 primary amine end groups form diamino Cu(II), diamino Zn(II), and tetramino Co(III) complexes that are identified spectrophotometrically and titrimetrically. The dendrimer–metal ion complexes catalyze the hydrolysis of p-nitrophenyl diphenyl phosphate in zwitterionic buffer solutions at pH ≤ 8.1 with relative activities Cu(II) > Zn(II) > Co(III). The rates of hydrolysis are faster with sodium perchlorate than with sodium chloride to control ionic strength. In sodium perchlorate solutions with Cu(II) the rates increase with increasing size of the dendrimer. In sodium chloride solutions with Cu(II) the rates decrease with increasing size of the dendrimer. Rate constants in buffered sodium chloride solutions of dendrimers and 1.0mM Cu(II) are 1.3–6.3 times faster than in the absence of Cu(II). The fastest hydrolyses occurred at a dendrimer primary amine to Cu(II) ratio NH₂/Cu ≤ 2. At NH₂/Cu = 4 and with the 1,4,7,10-tetraazacyclodecane complex of Cu(II) hydrolysis rates were much slower. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2727–2736, 1999     

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.     

稀土元素与NEB二元配合物的pH电位法分析

氨三乙氧基三苯甲酸(ＮＥＢ)(ＮＥＢ·ＨＣｌ的分子结构式见下图)作为有立体选择性的配体,它与铀酰离子ＵＯ2(Ⅱ)配位作用已有报导[1]。在对ＮＥＢ质子化常数及二元体系Ｍ(Ⅱ)-ＮＥＢ·ＨＣｌ(Ｍ=Ｃｄ、Ｃｏ、Ｎｉ、Ｃｕ和Ｚｎ)配合物的稳定常数测定的基础上[2],本文在25℃及离子强度为0 2ｍｏｌ/ＬＫＮＯ3的条件下,用精密ｐＨ电位法考察二元体系ＲＥ(ＩＩＩ)—ＮＥＢ(ＲＥ=Ｌａ→Ｎｄ,Ｓｍ→Ｌｕ,Ｙ)中存在的配合物物种及其稳定常数。ＮＥＢ·ＨＣｌ结构式1　实验部分1 1　试剂和仪器ＮＥＢ·ＨＣｌ(Ｈ3Ｌ·ＨＣｌ,Ｌ3-=Ｃ27Ｈ24ＮＯ9)…     

Mono(amidinate) rare earth metal bis(alkyl) complexes: Synthesis,structure and their activity for l-lactide polymerization

Alkane elimination reaction between Ln(CH₂SiMe₃)₃(THF)₂ (Ln = Y, Lu) with one equivalent of the amidines with different steric demanding HL ([CyC(N-2,6-ⁱPr₂C₆H₃)₂]H (HL₁), [CyC(N-2,6-Me₂C₆H₃)₂]H (HL₂), [PhC(N-2,6-Me₂C₆H₃)₂]H (HL₃)) in THF afforded a series of mono(amidinate) rare earth metal bis(alkyl) complexes [CyC(N-2,6-ⁱPr₂C₆H₃)₂]Ln(CH₂SiMe₃)₂(THF) (Ln = Y (1), Lu (3)), [CyC(N-2,6-Me₂C₆H₃)₂]Ln(CH₂SiMe₃)₂(THF)₂ (Ln = Y (4), Lu (6)), and [PhC(N-2,6-Me₂C₆H₃)₂]Y(CH₂SiMe₃)₂(THF)₂ (7) in 75–89% isolated yields. For the early lanthanide metal Nd, THF slurry of NdCl₃ was stirred with three equiv of LiCH₂SiMe₃ in THF, followed by addition of one equiv of the amidines HL₁ or HL₂ gave an “ate” complex [CyC(N-2,6-ⁱPr₂C₆H₃)₂]Nd(CH₂SiMe₃)₂(μ-Cl)Li(THF)₃ (2) in 48% yield and a neutral [CyC(N-2,6-Me₂C₆H₃)₂]Nd(CH₂SiMe₃)₂(THF)₂ (5) in 52% yield, respectively. They were characterized by elemental analysis, FT-IR, NMR spectroscopy (except for 2 and 5 for their strong paramagnetic property). Complexes 2, 3, 4 and 5 were subjected to X-ray single crystal structure determination. These neutral mono(amidinate) rare earth metal bis(alkyl) complexes showed activity towards l-lactide polymerization to give high molecular weight and narrow molecular weight distribution polymers.     

Anhydrous mono- and dinuclear tris(quinolinolate) complexes of scandium: the missing structures of rare earth metal 8-quinolinolates

The first monomeric anhydrous scandium tris(8-quinolinolate) complex 1 with the 2-amino-8-quinolinolate ligands and the Sc(2)Q(6) dinuclear complex 2 with the unsubstituted 8-quinolinolate ligands have been synthesized and characterized by X-ray analysis and DFT calculations. The intramolecular hydrogen bonds appear to be responsible for the unique monomeric structure of complex 1. The DFT-based analysis of the electron density topology reveals the (3,-1) critical points corresponding to the O···H and N···H bonds. The two scandium atoms in compound 2 are inequivalent due to different ligand surroundings. They are coordinated by seven (5O, 2N) and eight (4O, 4N) ligand atoms. The increase in the coordination number is accompanied by a decrease in the positive charge of the metal atom as evidenced by the DFT calculations.     

Hydrogenation of carbon monoxide by tetranuclear rare earth metal polyhydrido complexes. Selective formation of ethylene and isolation of well-defined polyoxo rare earth metal clusters

The reaction of the tetranuclear rare earth metal polyhydrido complexes {Cp'Ln(mu-H)2}4(THF) (Cp' = C5Me4SiMe3, Ln = Y (1a), Lu (1b)) with carbon monoxide (1 atm) yielded ethylene and the corresponding tetraoxo cubane complexes (Cp'Ln)4(mu3-O)4 (Ln = Y (5a), Lu (5b)). Stepwise formation of some key reaction intermediates, such as oxymethylene complexes (Cp'Ln)4(mu-OCH2)(mu-H)6(THF) (Ln = Y (2a), Lu (2b)), enolate species (Cp'Y)4(OCH=CH2)(mu-O)(mu-H)5(THF) (3), and dioxo complex (Cp'Y)4(mu3-O)2(mu-H)4(THF) (4), was confirmed. The molecular structures of 2a, 4, and 5b were determined by X-ray diffraction studies.     

Bis(imidazolin-2-iminato) rare earth metal complexes: synthesis, structural characterization, and catalytic application

Reaction of anhydrous rare earth metal halides MCl(3) with 2 equiv of 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-imine (Im(Dipp)NH) and 2 equiv of trimethylsilylmethyl lithium (Me(3)SiCH(2)Li) in THF furnished the complexes [(Im(Dipp)N)(2)MCl(THF)(n)] (M = Sc, Y, Lu). The molecular structures of all three compounds were established by single-crystal X-ray diffraction analyses. The coordination spheres around the pentacoordinate metal atoms are best described as trigonal bipyramids. Reaction of YbI(2) with 2 equiv of LiCH(2)SiMe(3) and 2 equiv of the imino ligand Im(Dipp)NH in tetrahydrofuran did not result in a divalent complex, but instead the Yb(III) complex [(Im(Dipp)N)(2)YbI(THF)(2)] was obtained and structurally characterized. Treatment of [(Im(Dipp)N)(2)MCl(THF)(n)] with 1 equiv of LiCH(2)SiMe(3) resulted in the formation of [(Im(Dipp)N)(2)M(CH(2)SiMe(3))(THF)(n)]. The coordination arrangement of these compounds in the solid state at the metal atoms is similar to that found for the starting materials, although the introduction of the neosilyl ligand induces a significantly greater distortion from the ideal trigonal-bipyramidal geometry. [(Im(Dipp)N)(2)Y(CH(2)SiMe(3))(THF)(2)] was used as precatalyst in the intramolecular hydroamination/cyclization reaction of various terminal aminoalkenes and of one aminoalkyne. The complex showed high catalytic activity and selectivity. A comparison with the previously reported dialkyl yttrium complex [(Im(Dipp)N)Y(CH(2)SiMe(3))(2)(THF)(3)] showed no clear tendency in terms of activity.     

Catalysis of the hydrolysis of di(p-nitrophenyl) methylphosphonate by polyamines

Conclusions The kinetics of the hydrolysis of di(p-nitrophenyl)methylphosphonate in aqueous solutions of triethylenetetramine and tetraethylenepentamine have been studied at various pH values. The catalytic rate constants for the neutral and monoprotonated forms of the polyamines are represented by the Brønsted equation as with the primary aliphatic amines and for the diprotonated forms they are represented together with the secondary aliphatic amines.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 756–759, April, 1987.     

Polyphenylcyclopentadienyl complexes of rare earth elements

Reaction of LnCl₃(thf) _x (Ln = Y, La, Yb, Lu) with NaCp^Phn (Cp^Phn = 1,3-Ph₂C₅H₃, 1,2,4-Ph₃C₅H₂, Ph₄C₅H) leads to formation of monocyclopentadienyl dichloride complexes Yb(Ph₂C₅H₃)Cl₂(thf)₃ (1), Ln(Ph₃C₅H₂)Cl₂(thf)₃ (Ln = Y (2), Lu (3)), La(Ph₄C₅H)Cl₂(thf)₃ (4). Molecular structures of 1, 2 and the polynuclear complex [(Ph₃C₅H₂)₃Lu₄(Cl)₇(O)(thf)₃] (5), which is a partial hydrolysis product of 3, have been established by the X-ray method.     

Supramolecular structures and stereochemical versatility of azoquinoline containing novel rare earth metal complexes

Rare earth complexes of 5-(phenylazo)-8-hydroxyquinoline (HL) of composition [M(L)(2)X.H(2)O] [where M=La, Ce, Pr, Nd and X=NO(3)(-) or NCS(-)] have been prepared and characterized on the basis of their chemical analyses, (1)H NMR, magnetic measurements, conductance, and visible and IR spectral data. Composition, conductance and IR spectral data of the complexes show that the HL acts as a bidentate monobasic ligand. The visible spectra of Pr(3+) and Nd(3+) show characteristic f-f transitions, and the nephelauxetic effect (1-beta) of these transitions has been evaluated. These data indicate the weak involvement of the 4f orbitals in complex formation.     

Catalytic addition of terminal alkynes to carbodiimides by half-sandwich rare earth metal complexes

The catalytic addition of terminal alkynes to carbodiimides has been achieved for the first time by use of half-sandwich rare earth metal complexes, such as {Me2Si(C5Me4)(NPh)}Y(CH2SiMe3)(THF)2, which offers a straightforward, atom-economic route to the N,N'-disubstituted propiolamidines which contain a conjugated C-C triple bond, a new family of amidines which were difficult to prepare by other means. A rare earth metal amidinate species was confirmed to be a true catalytic species in this process, thus demonstrating for the first time that an amidinate unit, though being often used as an ancillary ligand for various organometallic complexes, can itself participate in a catalytic reaction under appropriate conditions.     

Catalytic enantioselective construction of tetrasubstituted carbons by self-assembled poly rare earth metal complexes

Rare earth metal-based enantioselective catalysts that can promote practical cyanation reactions of ketones and ketoimines were developed. These catalytic enantioselective tetrasubstituted carbon-forming reactions are useful platforms for the synthesis of biologically active compounds. ESI-MS and crystallographic studies of the asymmetric catalysts revealed that the active catalysts are polymetallic complexes produced through the assembly of modules. The higher-order structure of the polymetallic complexes has strong effects on catalyst activity and enantioselectivity. Controlling the higher-order structure of artificial polymetallic asymmetric catalysts is a new strategy for optimizing asymmetric catalysts. Recent progress in this approach is also described.     

双水杨醛缩乙二胺稀土配合物的合成及表征

近年来对近红外发光稀土配合物的研究逐渐引起人们的重视[1 7]。本文合成了双水杨醛缩乙二胺(Ｃ16Ｈ16Ｎ2Ｏ2,Ｈ2Ｌ)合Ｎｄ(Ⅲ)、Ｇｄ(Ⅲ)、Ｙｂ(Ⅲ)配合物,报道该Ｓｈｉｆｆ碱配体对Ｎｄ(Ⅲ)、Ｙｂ(Ⅲ)离子近红外发光的敏化作用。1　实验部分浓盐酸和盐酸羟胺溶解稀土氧化物(广东珠江冶炼厂产品,纯度大于99 95%)并将所得溶液蒸至近干,得到相应的稀土氯化物,加入无水乙醇溶解得ＬｎＣｌ3(Ｌｎ=Ｎｄ,Ｙｂ,Ｇｄ),回流条件下将稀土氯化物乙醇溶液逐滴加入双水杨醛缩乙二胺[8]乙醇溶液中,稀土氯化物和配体为1∶2(Ｖ∶Ｖ)。回流反应10ｈ后得…     

Role of rare earth (RE) semiconductors on the decomposition of barium bromate

Barium bromate decomposes in the solid state through various stages: (i) initial gas evolution, (ii) induction period, (iii) slow linear reaction, (iv) acceleratory and decay stages. Rare earth semiconductors (p-type), Gd₂O₃ and Dy₃O₃ facilitate the acceleratory and decay stages without affecting the induction and linear periods. The extent of decomposition is higher in the case of mixture than that of the pure salt. The data are discussed in the light of theories of Prout—Tompkins and Avarami-Erofeev mechanisms exploring that nucleation occurs in a chain branching manner and there is two dimensional growth of nuclei.

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Zusammenfassung Bariumbromat zersetzt sich im festen Zustand über verschiedene Schritte: (i) anfängliche Gasentwicklung, (ii) Induktionsperiode, (iii) langsame lineare Reaktion, (iv) Beschleunigungs- und Abschlußschritt. Seltenerdenhalbleiter (vomp-Typ) erleichtern die Beschleunigungs- und Abschlußschritte, ohne die Induktions- und die lineare Periode zu beeinflussen. Das Ausmaß der Zersetzung ist im Falle von Gemischen höher als bei reinen Salzen. Die Angaben wurden im Hinblick auf die Mechanismentheorien von Prout-Tompkins und Avarami-Erofeev besprochen, die besagen, daß die Keimbildung auf kettenverzweigende Weise erfolgt und daß ein zweidimensionales Keimwachstum stattfindet.

     

Mixed borohydride-chloride complexes of the rare earth elements

Mixed borohydride-chloride complexes of lanthanum and neodymium having the 2,5-bis{N-(2,6-diisopropylphenyl)iminomethyl}pyrrolyl ligand in the coordination sphere were synthesised by the reaction of potassium 2,5-bis{N-(2,6-diisopropylphenyl)iminomethyl}pyrrolyl [(DIP₂-pyr)K] with a 1:1 mixture of [Ln(BH₄)₃(THF)₃] and LnCl₃ (Ln = La, Nd). Both compounds are dimeric in the solid state. The metal atoms are bridged almost symmetrically by two μ-chlorine atoms. Quantum chemical calculations for the lanthanum compound were performed to obtain a deeper insight into the bonding in the molecule.