Cleavage of nucleotides by Ce4+ and the lanthanide metal complexes

The cleavage of adenosine-5'-monophosphate (5'-AMP) and guanosine-5'-monophosphate (S-GMP) by Ce4+ and lanthanide complex of 2-carboxyethylgermanium sesquioxide (Ge-132) in acidic and near neutral conditions was investigated by NMR, HPLC and measuring the liberated inorganic phosphate at 37 degrees C and 50 degrees C, The results showed that 5'-GMP and 5'-AMP was converted to guanine (G), 5'-monophosphate (depurination of 5'-GMP), ribose (depurination and dephosphorylation of 5'-GMP), phosphate and adenine (A), 5'-monophosphate (depurination of 5'-AMP), ribose (depurination and dephosphorylation of 5'-AMP), phosphate respectively by Ce4+. In presence of lanthanide complexes, 5'-GMP and 5'-AMP were converted to guanosine (Guo) and phosphate and adenosine (Ado) and phosphate respectively. The mechanism of cleaving 5'-GMP and 5'-AMP is hydrolytic scission.

Studies of non-covalent protein complexes by MALDI methods

Several specific non-covalent protein complexes were successfully observed by matrix assisted desorption ionization mass spectrometry(MALDI MS). The methods described in this paper include the matrixes use of sinapinic acid(SA) and 6-aza-2-thiothymine (ATT) in neutral pH solution, as well as the improvement of two-layer sample preparation method to achieve a high sensitivity detection of stable non-covalent complexes, Myoglobin-heme complex was found simultaneously with the sinapinic acid matrix in the various pH solution(pH=2 or pH=5), The RNase S complex showed a striking intensity at the first shot, which was decreased with more laser shots. Most importantly, the observation of specific non-covalent complex in the brome mosaic virus(BMV) coat proteins would open up a new possibility to investigate the assembly and disassembly of viral capsids.

Half-sandwich cyclopentandienyl molybdenum and tungsten nitrosyl complexes containing bidentate sulfur ligands

Half-sandwich nitrosyl complexes Cp*M(NO)I-2 (M = Mo, or W) react with dithiocarbamates (NaS2CNMe2 and NaS2CNEt2) in THF to form of complexes: Cp*Mo(NO)I (S2CNMe2) (1), Cp*Mo(NO)I(S2CNEt2) (2), Cp*W(NO)I(S2CNMe2) (3) and Cp*W(NO)I(S2CNEt2) (4) in high yields. Treatments of Cp*M(NO)I-2 (M = Mo, W) or [CpMo(NO)I-2](2) with phosphinodithioate (NaS2PMe2) and phosphorodithioate [(NH4)S2P(OMe)(2)] result in complexes: Cp*Mo(NO)I(S2PMe2) (5a), CpMo(NO)I (S2PMe2) (5b), Cp*Mo(NO)(S2PMe2)(2) (6a), CpMo (NO) (S2PMe2)(2) (6b) and Cp*Mo(NO)I[S2P(OMe)(2)] (7), Cp*W(NO)I(S2PMe2) (8), Cp*W(NO) I[S2P(OMe)](2) (9). Treatment of (5a) and (5b) with an excess of NaS2PMe2 gives (6a) and (6b). The complexes have been characterized by their elemental analyses, i.r., H-1, C-13-n.m.r. and by EI-MS spectrometry.

Biological effect of rare earth (I) - Content and distribution of rare earth in normal human plasma

The content and distribution of rare earth(RE) in normal human plasma have been investigated by ultrafiltration, FPLC and ICP-MS methods, The results showed that there are trace RE in normal human plasma, and their contents are in accordance with their abundance, The RE can bond with immunoglobulin G(IgG), transferrin(Tf) and albumin(Alb) species, but mostly bond with Tf.

The use of half-sandwich iridium dithiolate and diselenolate complexes, Cp*Ir(L)(ER)(2) (L = CO, PMe3, PPh3; ER = SPh, SePh, SeMe), for the synthesis of heterodimetallic compounds. The molecular structure of Cp*Ir(CO)(mu-SePh)(2)[Mo(CO)(4)]

Carbonyl-iridium half-sandwich compounds, Cp*Ir(CO)(EPh)(2) (E = S, Se), were prepared by the photo-induced reaction of Cp*Ir(CO)(2) with the diphenyl dichalcogenides, E2Ph2, and used as neutral chelating ligands in carbonylmetal complexes such as Cp*Ir(CO)(mu-EPh)(2)[Cr(CO)(4)], Cp*Ir(CO)(mu-EPh)(2)[Mo(CO)(4)] and Cp*Ir(CO)(mu-EPh)(2)[Fe(CO)(3)], respectively. A trimethylphosphane - iridium analogue, Cp*Ir(PMe3)(mu-SeMe)(2)[Cr(CO)(4)], was also obtained. The new heterodimetallic complexes were characterized by IR and NMR spectroscopy, and the molecular geometry of Cp*Ir(CO)(mu-SePh)(2)[Mo(CO)(4)] has been determined by a single crystal X-ray structure analysis. According to the long Ir...Mo distance (395.3(1) Angstrom), direct metal-metal interactions appear to be absent. (C) 1998 Elsevier Science S.A. All rights reserved.

pH-potentiometric study on rare earths and calcium binary and ternary complexes with DL-malic acid and L-hydroxyproline

The stability constants of M-L binary system and M-L-L' (M = La3+ similar to Yb3+, Y3+ and Ca2+; L= DL-malic aicd, L' = L-hydroxyproline) ternary system were determined by pH-(0)-tentiometric method under the simulating physiological condition(37 degrees C, I=0.15 mol/L NaCl). The complex species MpLqLr'H-s(abbr as pqrs) in the sytems were ascertained by program COMPLEX. The results show that there are three species(1101, 1100 and 1200) in M-L binary system and one species(1010) in M-L' binary system. In addition to the above four species, a new species, 1112 was found in the M-L-L' ternary system, which is the only species of mixed ligands. Rare earth ions form more stable complexes than calcium ion does and the stability differences between their complexes in the ternary system are less than that in the binary system. The distributions of all the species in La-L-L' ternary system vs pH are discussed.

The polymerization of methyl methacrylate with a new Nd(O-i-Pr)(3)-Al(i-Bu)(3) catalyst system

Methyl methacrylate (MMA) was polymerized with the rare earth coordination catalyst-system of Nd(O - i-Pr)(3) in toluene. The influences of various ligands in neodymium complexes, molar ratio of Al/Nd, catalyst concentration, catalyst aging time, solvents, the third component CCl4, temperature and time on the polymerization of MMA were studied. The results showed that the polymerization conversion reached more than 80% at a catalyst concentration of 9.2 x 10(-3) mol/L. The appropriate molar ratio of CCl4/Nd was 4. Hydrocarbon was preferred for the polymerzation to obtain a high conversion and a high <(M)over bar w> of PMMA. The H-1 NMR spectra of PMMA indicated that the lower the temperature, the higher the syndiotactic content of PMMA was obtained.

Synthesis, crystal structure and magnetic properties of a series of polymeric lanthanoid-copper complexes [Ln(2)Cu(3){O(CH2-CO2)(2)}(6)].nH(2)O (Ln=La, Nd, n=9; Ln=Er, n=6)

The reaction of diglycolic acid, O(CH2CO2H)(2), with Cu(NO3)(2) . H2O and lanthanoid nitrate hydrate produces a series of novel Ln-Cu mixed metal complexes, [Ln(2)CU(3){O(CH2CO2)(2)}(6)]. nH(2)O (Ln = La, Nd, n = 9; Ln = Er, n = 6), which have been characterized by elemental analysis, i.r. spectroscopy, magnetic measurements and X-ray crystallography. The Ln(3+) and Cu2+ ions are connected by the carboxylate groups of the ligands, resulting in the formation of a complicated network.

Ion/neutral complex-mediated reactions generated from some ionized tetrahydroimidazole-substituted methylene beta-diketones

The dissociation of gaseous metastable ions of m/z 153 and the formation of ions of m/z 139 from the unimolecular fragmentations of ionized tetrahydroimidazole-substituted methylene beta-diketones were examined by tandem mass spectrometry. In addition, some other fragments accompanying the elimination of either an H2O molecule or an CHO. radical were also observed in the collision-induced dissociation spectra of molecular ions of the compounds bearing an aromatic ring. Collision-induced dissociation and isotopic labeling showed that these processes may involve reactions of intermediate ion/neutral complexes and multistep rearrangements. The corresponding mechanisms are discussed. (C) 1997 by John Wiley & Sons, Ltd.

Synthesis of lanthanide-alkylaluminium bimetallic complexes and studies on their catalytic activities for polymerization of some polar monomers

Three new lanthanide (Ln)-alkylaluminium (Al) bimetallic complexes with the formula [(mu-CF3CO2)(2)Ln(mu-CF3CHO2)AIR(2) . 2THF](2) (Ln = Nd, Y, R=i-C4H9 (i-Bu); Ln=Eu, R=C2H5(Et); THF=tetrahydrofuran) were synthesized by the reaction of Ln(CF,CO,), (Ln=Nd, Y) with HAI (i-Bu)(2) and of Eu(CF3CO2)(3) with AlEt(3), respectively. Their crystal structures were determined by X-ray diffraction at 233 K. [(mu-CF3CO2)(2)Nd (mu-CF3CHO2)Al(i-Bu)(2) . 2THF](2) (Nd-Al) and [(mu-CF3CO2)(2)Y(mu-CF3CHO2)Al(i-Bu)(2) . 2THF](2) (Y-Al) are isomorphous and crystallize in space group with a=12.441(3) Angstrom [12.347(5) Angstrom for Y-Al], b=12.832(3) Angstrom [12.832(4) Angstrom], c=11.334(3) Angstrom [11.292(8) Angstrom], alpha=104.93 (2)degrees [104.45(4)degrees], beta=98.47(2)degrees [98.81(4)degrees], gamma=64.60(2)degrees [64.30(3)degrees], R=0.519 [0.113], R(w)=0.0532 [0.110], Z=1 and [(mu-CF3CO2)(2)Eu(CF3CHO2)AlEt(2) . 2THF](2)(Eu-Al) in space group P2(1)/n with a=11.913(6) Angstrom, b=14.051(9) Angstrom, c=17.920(9) Angstrom, alpha=101.88(11)degrees, beta=gamma=90 degrees, R=0.0509, R(w)=0.0471 and Z=2. The six CF3CO2- (including CF3CHO2-) of each complex, among which pairs are equivalent, coordinated to Ln and Al in three patterns: (A) the two oxygen atoms in one of the three CF3CO2- type coordinated to two different Ln; (B) the two oxygen atoms in the second of CF3CO2- type coordinated to Ln and Al, respectively; (C) one of the two oxygen atoms in the third CF3CO2- type bidentately coordinated to two Ln and another oxygen coordinated to Al and one of the two Ln, respectively. Unlike types A and B, in type C the carboxyl carbon with a hydrogen atom bonded to it was found to appear as an sp(3)-hybridized configuration rather than an sp(2)-one. 1D and 2D NMR results further confirmed the existence of such a disproportionated CF3CHO2- ligand. Methyl methacrylate (MMA) and epichlorohydrin (ECH) could be polymerized by Y-Al or Eu-Al as a single-component catalyst and highly syndiotactic poly(MMA) was obtained. THF could also be polymerized by Y-Al in the presence of a small amount of ECH.

Syntheses and reactions of heterometallic complexes of nickel and copper with tetrathiotungstates. The molecular structures of [Ph(4)P](2)[S2W(mu-S)(2)Ni(S-2)] and W(mu-S)(4)Cu-2(PPh(3))(4)center dot py

Reaction of [Ph(4)P]2WS4 With NiCl2 in methanol solution in the presence of NaOCH3 leads to the formation of [Ph(4)P](2) [S2W(mu-S)(2)Ni(S-2)] (I) A Similar reaction between (NH4)(2)WS4 and NiCl2 under O-2 atmosphere in the presence of Ph(4)PCl or (n)Bu(4)NCl affords [Ph(4)P](2)([(S-2)W(O)(mu-S)(2)]Ni-2] (IIa) and [(n)Bu(4)N](2)([(S-2)W(O)(mu-S)(2)]Ni-2} (IIb) Under argon the same reaction gives [Ph(4)P](2)[Ni(WS4)(2)] (IIIa) and [(n)Bu(4)N](2)[Ni(WS4)(2)] (IIIb). [Ph(4)P](2)[Ni(WOS3)(2)] (IV) and [Ph(4)P](2)[Ni(WO2S2)(2)] (V) can be prepared from the reaction of [Ph(4)P]2WOS3 and [Ph(4)P]2WO2S2 with NiCl2. Treatment of (NH4)(2)WS4 with CuCl in the presence of PPh(3) in boiling pyridine produces W(mu-S)(4)Cu-2(PPh(3))(3) (VI), which can further react with excess PPh(3) to give W(mu-S)(4)Cu-2(PPh(3))(4) . py (VII). Complex I crystallizes in the space group P2(1)/n with the cell parameters: a = 20.049(4), b = 17.010(4), c = 14.311(7) Angstrom; beta = 110.24(3)degrees and Z = 4; R = 0.058 for 4267 independent reflections. The structural study confirms that complex I contains two terminal sulfide ligands, two bridging sulfide ligands, a side-on disulfide ligand, and a planar central W(mu-S)(2)Ni four membered ring. Complex VII crystallizes in the space group C2/c with the cell parameters: a = 26.436(8), b = 20.542(6), c = 19.095(8) Angstrom; beta = 125.00(3)degrees and Z = 4; R = 0.080 for 3802 independent reflections. The structural study reveals a perfect linear arrangement of the three metal atoms Cu-W-Cu.

Sol-gel synthesis and luminescence of Y4Al2O9:RE3+(RE=Eu, Tb)

Y4Al2O9 (YAM) was prepared by a sol-gel process, using yttrium and aluminum citrate complexes as precursors. The sol-gel process produced single-phase YAM at 900 degrees C, as opposed to the conventional solid-state reaction, which led to the formation of other phases, even if at 1600 degrees C. The emission and excitation spectra of Eu3+ and Tb3+ in YAM showed the existence of two luminescence centers, agreeing with the crystal structure of YAM. The spectral properties of the samples are discussed.

A STUDY ON THE LUMINESCENCE PROPERTIES OF EU3+ AND DY3+ IN M(2)RE(8)(SIO4)(6)O-2 (M=MG, CA RE=Y, GD, LA)

In this paper, the luminescence properties of Eu3+ and Dy3+ in the oxyapatites M(2)RE(8)(SiO4)(6)O-2 (M=Mg, Ca; RE=Y, Gd, La) were studied. The spectral characters of Eu3+ were discussed in relation to the crystal structure. The dependence of the red-to-orange intensity ratio and the position of the charge transfer band of Eu3+ and the yellow-to-blue intensity ratio of Dy3+ together with their fluorescence intensities (I-R for Eu3+ and I-Y for Dy3+) On the M(2+) and the substitution of BO45- and PO43- for SiO44- was discussed. Finally, the concentration quenching of Dy3+ luminescence was reported.

SYNTHESES, CHARACTERIZATION AND CRYSTAL-STRUCTURES OF THE COMPLEXES OF RARE-EARTH WITH O-CHLOROBENZOIC ACID

REL3.H2O (RE=Y, La is similar to Lu; HL = o-chlorobenzoic acid) were synthesized. Their thermal decomposition and IR spectra were studied. The crystal structures of the complexes of neodymium, terbium and lutetium were determined by X-ray diffraction method. They crystallize in the monoclinic space group P2(1)/n and show infinite chain structures. The coordination numbers of rare earth ions are nine.