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Mono
Kinds of Mono Selected AbstractsFolate deficiency in human peripheral blood lymphocytes induces chromosome 8 aneuploidy but this effect is not modified by riboflavinENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 1 2010Juan Ni Abstract Chromosome 8 aneuploidy is a common event in certain cancers but whether folate (F) deficiency induces chromosome 8 aneuploidy is not known. Furthermore the impact of riboflavin (R) deficiency, which may alter activity of a key enzyme in folate metabolism, on these events is unknown. Therefore, the aim of our research was to test the following hypotheses: (a) F deficiency induces chromosome 8 aneuploidy; (b) chromosome 8 aneuploidy is affected by F deficiency to a similar degree as chromosome 17 and (c) R deficiency aggravates the risk of aneuploidy caused by F deficiency. These hypotheses were tested in long-term cultures of lymphocytes from twenty female healthy volunteers (aged 30,48 years). Lymphocytes were cultured in each of the four possible combinations of low (L) and high (H) F (LF, 20 nmol/L, HF 200 nmol/L, respectively) and L and H R (LR 1 nmol/L, HR 500 nmol/L, respectively) media (LFLR, LFHR, HFLR, HFHR) for 9 days. Chromosomes 8 and 17 aneuploidy was measured in mononucleated (MONO) and cytokinesis-blocked binucleated (BN) cells using dual-color fluorescence in situ hybridization (FISH) with fluorescent centromeric probes specific for chromosomes 8 and 17. Culture in LF media (LFLR or LFHR) induced significant and similar increases in frequencies of aneuploidy of chromosomes 8 and 17 (P < 0.001) relative to culture in HF media (HFLR or HFHR). There was no significant effect of R concentration on aneuploidy frequency for either chromosome. We conclude that F deficiency is a possible cause of chromosome 8 aneuploidy. Environ. Mol. Mutagen. 2010. © 2009 Wiley-Liss, Inc. [source] Essential fatty acid enrichment of cultured rotifers (Brachionus plicatilis, Müller) using frozen-concentrated microalgaeAQUACULTURE NUTRITION, Issue 4 2009L.H. SEYCHELLES Abstract There is a growing interest in preserving microalgal preparations to maintain constant properties over a long period. The aim is to ensure sufficient delivery of essential fatty acids (and other key nutrients) to mollusc and crustacean larvae and to zooplankton used as live prey in the first feeding of fish larvae. For example, the rotifer Brachionus plicatilis has to be enriched with polyunsaturated fatty acids (PUFA) prior to fish feeding. We used four microalgal species [Isochrysis galbana (T-ISO), Chaetoceros muelleri (CHGRA), Pavlova lutheri (MONO), and Nannochloropsis sp.] both as fresh culture or in a frozen-concentrated form to enrich rotifers. Overall, rotifers had similar relative fatty acid levels when fed the frozen-concentrated or fresh microalgal diets. The levels of 20:4n-6, 22:6n-3, and 20:5n-3 between B. plicatilis and the microalgal diets were linearly correlated. The fatty acid 20:4n-6 was the most readily assimilated: the content found in rotifers reached half the level measured in the microalgal diets. Our results indicate that both the fresh and frozen-concentrated forms of the four microalgal species can be used to enrich PUFA levels in rotifers. Further experiments should be conducted to test if assimilation differs when rotifers are enriched with mono- or multispecific microalgal preparations. [source] Evaluation of tumor affinity of mono-[123I]iodohypericin and mono-[123I]iodoprotohypericin in a mouse model with a RIF-1 tumorCONTRAST MEDIA & MOLECULAR IMAGING, Issue 3 2007Humphrey Fonge Abstract In this study we have compared the tumour-seeking properties of mono-[123I]iodoprotohypericin and mono-[123I]iodohypericin in C3H mice with a subcutaneous radiation-induced fibrosarcoma-1 tumor. After intravenous injection, both tracers were rapidly cleared from all organs and were retained by the tumors. There was no significant difference in tumor uptake of the two tracers at all studied time points (p,>,0.05). To study the plausible mechanism of hypericin and mono-iodohypericin uptake in tumor, their plasma binding profile was investigated. Both agents show high affinity for low-density lipoproteins and to a lesser extent high-density lipoproteins and other heavy proteins. Mono-[123I]iodohypericin appears to be more promising as a tumor diagnostic agent, given its faster clearance from all organs. Copyright © 2007 John Wiley & Sons, Ltd. [source] Mono-, Bi-, Tri- and Tetranuclear Palladium(II), Copper(I), and Gold(I) Complexes of Morpholine- and N -Methylpiperazine-Functionalized Cyclodiphosph(III)azans, cis -[(tBuN-,)2(PNC4H8X)2] (X = O, NMe)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 26 2010Maravanji S. Balakrishna Abstract Bis(amido)cyclodiphosphazanes, cis -[(tBuN-,)2(PNC4H8O)2] (2) and cis -[(tBuN-,)2(PNC4H8NMe)2] (3) were synthesized by treating the corresponding amines with cis -[ClP(tBuN-,)2PCl] (1). The stoichiometric reactions of 2 or 3 with elemental sulfur and selenium afforded the bis-chalcogenides, cis -[(tBuN-,)2(P(E)NC4H8X)2] (X = O, E = S; 4, X = NMe, E = S; 5, X = O, E = Se; 6, X = O, E = Se; 7). The reactions of 2 or 3 with [PdCl2(SMe2)2] produced exclusively the mononuclear trans -[PdCl2{(tBuN-,)2(PNC4H8X)2}2] (X = O; 8, X = NMe; 9), whereas the reactions with [Pd(,-Cl)(,3 -C3H5)]2 afforded the bimetallic complexes [{PdCl(,3 -C3H5)}2{(tBuN-,)2(PNC4H8X)2}] (X = O; 10, X = NMe; 11) in good yield. Treatment of 2 or 3 with [AuCl(SMe2)] in 1:1 and 1:2 molar ratios yielded the mono- and binuclear complexes, [{AuCl(tBuN-,)2(PNC4H8O)2}] (X = O; 12, X = NMe; 13), [{AuCl}2{(tBuN-,)2(PNC4H8O)2}] (X = O; 14, X = NMe; 15), respectively. The PdII (8) and AuI (12) complexes were used as metallo-ligands to prepare homo- and heterometallic complexes, trans -[PdCl2{(tBuN-,)2(PNC4H8O)2}2{Pd(,3 -C3H5)Cl}2] (16), trans -[PdCl2{(tBuN-,)2(PNC4H8O)2}2(AuCl)2] (17), and [Cu(CH3CN)(,-Cl)2Cu(CH3CN){(tBuN-,)2(PNC4H8O)2}2(AuI)2](18). The crystal structures of 2, 4, 7,9, 14, 15, and 18 were established by single-crystal X-ray diffraction studies. [source] Dehydrogenation of Hydridoirida-,-diketones in Methanol: The Selective Formation of Mono- and Dinuclear Acyl ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2010Roberto Ciganda Abstract The hydridoirida-,-diketone [IrH{(PPh2(o -C6H4CO))2H}Cl] (1) reacts with diimines (NN) or with pyridine (py) in refluxing methanol to undergo dehydrogenation. The reactions afford selectively the cis -acyl, trans -phosphane isomers of the cationic [Ir(PPh2(o -C6H4CO))2(NN)]+ {NN = 2,2,-bipyridine (2); R,N=C(CH3),C(CH3)=N,R, [R = R, = NH2 (3); R = R, = OH (4); R = OH, R, = NH2 (5)]} or neutral [IrCl(PPh2(o -C6H4CO))2(py)] (6) derivatives. The reactions are faster for ligands containing amino substituents. Refluxing 1 in MeOH affords the formation of an equimolar mixture of dimercationic species [Ir2(,-Cl)(,-PPh2(o -C6H4CO))2(PPh2(o -C6H4CO))2]+ (7a and 7b) containing two acyls and a chloride as bridging groups. The isomers could be separated by fractional precipitation. Compound [3]Cl, containing amino substituents in the imino functionalities, catalyses the hydrogen transfer from 2-propanol to cyclohexanone to afford cyclohexanol. All the complexes were fully characterised spectroscopically. Single crystal X-ray diffraction analysis was performed on complexes 6 and [7b]ClO4. [source] Comparative Solution Equilibrium Study of the Interactions of Copper(II), Iron(II) and Zinc(II) with Triapine (3-Aminopyridine-2-carbaldehyde Thiosemicarbazone) and Related LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2010Éva A. Enyedy Abstract The interactions of CuII, ZnII and FeII with Triapine (3-aminopyridine-2-carbaldehyde thiosemicarbazone), which is currently undergoing phase II clinical trials as a chemotherapeutic antitumour agent, were investigated in a water/DMSO mixture. The proton-dissociation constants of the ligands, the stability constants and the coordination modes of the metal complexes formed were determined by pH-potentiometric, UV/Vis spectrophotometric, EPR, 1H NMR spectroscopic and ESI-MS methods. Two N-terminally dimethylated derivatives of Triapine were also studied. Mono- and bis-ligand complexes in different protonation states were identified. Furthermore, the formation of the dinuclear species [Cu2L3]+ was confirmed for all ligands by EPR spectroscopy and ESI-MS measurements. The results showed that the N-terminally dimethylated ligands are much more potent chelators than Triapine for the divalent metal ions studied. All three ligands formed the least stable complexes with ZnII, whereas the FeII complexes were somewhat more stable than the corresponding CuII species. [source] Mono- and Binuclear Arylnickel Complexes of the ,-Diimine Bridging Ligand 2,2,-Bipyrimidine (bpym)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2010Axel Klein Abstract The mono- and binuclear organometallic NiII complexes [(,-bpym){Ni(Mes)Br}n] (bpym = 2,2,-bipyrimidine; n = 1 or 2; Mes = mesityl = 2,4,6-trimethylphenyl) were prepared and characterised electrochemically and spectroscopically (NMR, UV/Vis/NIR) in detail. The long-wavelength absorptions for the binuclear complex reveal a marked electronic coupling of the two metal centres over the ligand bridge via their low-lying ,*-orbitals. While the mononuclear complex undergoes rapid dissociation of the bromido ligand after one-electron reduction the binuclear derivative exhibits reversible reductive electrochemistry and both of them yield stable radical anionic complexes with mainly bpym ligand centred spin density as shown by EPR spectroscopy of the free ligand bpym and the nickel complexes. The molecular structure of the binuclear bpym complex [(,-bpym){Ni(Mes)Br}2] was studied by EXAFS in comparison to the mononuclear analogue [(bpym)Ni(Mes)Br] revealing markedly increased Ni,C/N distance of the first coordination shell for the binuclear derivative suggesting an optimum overlap for the mononuclear complex, while two nickel complex fragments {Ni(Mes)Br} are seemingly too large to fit into the bis-chelate coordination site. [source] Mono(aryloxido)Titanium(IV) Complexes and Their Application in the Selective Dimerization of EthyleneEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2009Jean-Benoit Cazaux Abstract We report on the synthesis of mono(aryloxido)titanium(IV) complexes of general formula {Ti[O(o -R)Ar]X3}, with X = OiPr, ArO = 2- tert -butyl-4-methylphenoxy and R = CMe3 (2a), CMe2Ph (2b) and CH2NMe2 (2c). Attempts to reach pure mono(aryloxido) complexes when R = CH2NMe(CH2Ph) (2d) or CH2N(CH2Ph)2 (2e) were unsuccessful. When R = CH2OMe, the analogous mononuclear complex was not obtained, and instead, a dinuclear complex [(2- tert -butyl-4-methyl-6-methoxymethylphenoxy) TiCl(OiPr)(,2 -OiPr)2TiCl(OiPr)2] (3) was formed. Complexes 2b and 3 were characterized by single-crystal X-ray diffraction. The former contains a tetrahedrally coordinated TiIV centre, whereas in the latter the aryloxido ligand behaves as a chelating,bridging ligand between the two, chemically very different metal centres that form two face-sharing octahedra. Different synthetic approaches starting from [Ti(OiPr)4] or [TiCl(OiPr)3] were evaluated and are discussed. The hemilabile behaviour of the aryloxido ligand resulting from reversible coordination of its side arm was studied by variable-temperature 1H NMR spectroscopy for 2c (R = CH2NMe2). Complexes 2a,d were contacted with ethylene and AlEt3 as cocatalyst. When activated with AlEt3 (3 equiv.) at 20 bar and 60 °C, complex 2c exhibits interesting activity (2100 g/gTi/h) for the selective dimerization of ethylene to 1-butene (92,% C4=; 99+% C4=1). Noticeable differences in catalyst activity were observed when the R group was modified. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Mono-, Bi- and Tridentate N-Heterocyclic Carbene Ligands for the Preparation of Transition-Metal-Based Homogeneous CatalystsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2009Rosa Corberán Abstract This microreview focuses on the preparation of homogeneous catalysts of group 8,11 metals containing N-heterocyclic carbene ligands. The current status of the design of mono-, bi- and tridentate NHC ligands is reviewed through the description of the authors' own work. The catalytic applications of such complexes include hydrogen-borrowing, C,C coupling, reduction of double bonds and C,H activation reactions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Reactions of [Hg(Tab)2](PF6)2 [Tab = 4-(trimethylammonio)benzenethiolate] with NaX (X = Cl, NO2, NO3): Isolation and Structural Characterization of a Series of Mono- and Binuclear Hg/Tab/X CompoundsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2008Xiao-Yan Tang Abstract The complex [Hg(Tab)2](PF6)2 [Tab = 4-(trimethylammonio)benzenethiolate] (1) reacts with one or two equivalents of NaCl to afford the mononuclear complex [Hg(Tab)2Cl](PF6) (2) and the dinuclear complex [{Hg(,-Tab)(Tab)Cl}2]Cl2·H2O (3·H2O), respectively. Similar reactions of 1 with NaCl and NaX (molar ratio = 1:1) produce the dinuclear species [{Hg(,-Tab)(Tab)Cl}2]X2 [X = NO2 (4), NO3 (5)], while those with NaNO2 or NaNO3 give rise to [{Hg(,-Tab)(Tab)X}2]X2 [X = NO2 (6), NO3 (7)]. Complexes 2,7 have been characterised by elemental analysis, IR, UV/Vis, and 1H NMR spectroscopy, and X-ray crystallography. The Hg atom of the [Hg(Tab)2Cl]+ cation in 2 adopts a T-shaped coordination geometry. Two [Hg(Tab)2Cl]+ cations in 3·H2O, 4, and 5 are linked by a pair of weak Hg,S bonds to form a dimeric [Hg(,-Tab)(Tab)Cl]22+ dication, and the centrosymmetric [Hg(,-Tab)(Tab)X]22+ dication in 6 and 7 consists of two [Hg(Tab)2X]+ cations linked by a couple of weak Hg,S bonds. The hydrogen-bonding interactions in 2,7 lead to the formation of interesting 2D (5, 7) or 3D (2,4, 6) hydrogen-bonded networks.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Benzylideneruthenium Complexes Bearing Pyridine-Based Ligands and Their Influence on the Formation of Mono- or Bis(pyridine) ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 34 2007Wen-Zhen Zhang Abstract Benzylideneruthenium complexes bearing the N-heterocyclic carbene (NHC) ligand 1,3-bis(2,6-dimethylphenyl)-4,5-dihydroimidazol-2-ylidene (H2IMe) and one or two pyridine-based ligands have been prepared by treating [RuCl2(=CHPh)(H2IMe)(PPh3)] with the corresponding pyridine derivative. X-ray crystallographic and mass spectrometric evidence is used to investigate the interconversion between mono- and bis(pyridine) complexes and the influence of the pyridine ligand on the formation of these complexes. The catalytic activity of these complexes has been tested in the ring-closing metathesis (RCM) reaction of diallylmalononitrile and the cross metathesis (CM) reaction of acrylonitrile with terminal olefins.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Bulky-Hindrance-Controlled Ligand Transformation from Linked Bis(amidinate) to Linked Imido-Amidinate Promoted by a Mono(cyclopentadienyl)titanium GroupEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2006Sheng-Di Bai Abstract A novel class of silyl-linked bis(amidinate) ligands [SiMe2{NC(Ph)N(2,6-R2Ph)Li}2] [L1 (R = H), L2 (R = Me), and L3 (R = iPr)] reacted with TiCl3(C5H5) to produce the half-sandwich titanium complexes 1, 2, and 3. The molecular structures of 1,3 were confirmed successfully by X-ray crystallography. An unprecedented intramolecular ligand transformation from the linked bis(amidinate) configuration to the linked imido-amidinate configuration took place in the cases of L1 and L2. It was found that the rearrangement process was related to the steric hindrance of the terminal substituents. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Synthesis and Characterization of Radical Cations Derived from Mono- and Biferrocenyl-Substituted 2-Aza-1,3-butadienes: A Study of the Influence of an Asymmetric and Oxidizable Bridge on Intramolecular Electron TransferEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 12 2005Vega Lloveras Abstract The synthesis and study of structural and electronic properties of mono-ferrocenyl ,-conjugated complexes 5a,d, whose electronic characteristics have been systematically varied by introducing an electron-donating or electron-withdrawing substituent either at the 1-position or at the 4-position of the 2-aza-1,3-butadiene moiety linked to the ferrocenyl unit, are presented. The structural and electronic properties of the homobimetallic complex 5f, with two ferrocene units linked through the asymmetric and oxidizable 2-aza-1,3-butadiene bridge, is also reported. The crystal structures of complexes 5b, 5d, and 5f show a large degree of conjugation in this family of compounds. Complexes 5 show a rich electrochemical behavior due both to the oxidation of ferrocenyl units and the 2-aza-1,3-butadiene bridge, as revealed by cyclic voltammetry. Radical cations 5+· were prepared from 5 by coulometric oxidations following their generation by absorption spectroscopy. The electronic properties of all reported neutral and oxidized ,-conjugated complexes have been investigated by means of UV/Vis,near-IR, EPR and 57Fe Mössbauer spectroscopy. The detailed study of mono-oxidized species 5a+·,5f+· has permitted the determination of the influence of an asymmetric bridge with an electroactive character on the intramolecular electron transfer (IET) phenomenon, thus demonstrating that the 2-aza-1,3-butadiene bridge promotes the IET between the two metallic units of 5f+· through two different pathways. The experimental data and conclusions are supported by DFT computations (B3LYP/3-21G*) and time-dependent DFT methods. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Mono- and Dinuclear CuII and ZnII Complexes of Cyclen-Based Bis(macrocycles) Containing Two Aminoalkyl Pendant Arms of Different LengthsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2005Carmen Anda Abstract The basicity and coordination properties towards CuII and ZnII of the bis(macrocycles) L1, L2 and L3 have been investigated by means of potentiometric, 1H NMR and UV/Vis spectroscopic titrations in aqueous solutions. The synthesis of L1 and L3 is also described. The three ligands are composed of two [12]aneN4 units separated by a p- phenylene spacer and differ in the length of the aminoalkyl pendant arms linked to each macrocyclic unit. L1,L3 form mono- and dinuclear complexes in aqueous solutions; in the dinuclear species each metal ion is coordinated by one of the two identical [12]aneN4 ligand moieties, as shown by the crystal structures of the complexes [Cu2L1]Cl4·8H2O, [Zn2L2](ClO4)4 and [Zn2L3](ClO4)4·H2O. In all structures the metal ion is pentacoordinate, and is bound to the four nitrogen donors of the cyclic unit and to the amine group of the side arm. The stability of both the [ML]2+ and [M2L]4+ complexes in aqueous solution decreases in the order L1 > L2 > L3. At the same time, both the [Cu2L]4+ and [Zn2L]4+ complexes show a different ability in proton binding among the three ligands, with the [M2L1]4+ complexes displaying the highest basicity. These results are explained in terms of the decreasing number of nitrogen donors involved in CuII or ZnII binding on passing from L1 to L3; in other words, while in the L1 dinuclear complexes each metal ion is coordinated to the four amine groups of a [12]aneN4 moiety and to the amine group of the side arm, in the L3 ones the metal cations are bound only to the four donor atoms of a cyclic moiety, the aminobutyl group not being coordinated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Mono-, Di- and Polymeric Calcium and Gadolinium Complexes of the Tripodal Ligand 2,2,,2,,-Nitrilotribenzoic AcidEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 4 2005Stefan Wörl Abstract Three novel carboxylate-bridged complexes incorporating the tripodal N,O ligand 2,2,,2,,-nitrilotribenzoic acid H3L of formula [CaII(H2L)(OH2)4][(H2L)]·4H2O (1), [CaII(OH2)4]-[CaII(L)(OH2)2]2·7H2O (2) and [GdIII(L)(OH2)3]2[GdIII(L)-(OH2)4]2·13H2O (3) were synthesized and characterized by X-ray crystallography. In all three complexes, the ligand H3L binds to the metal centre only by its three carboxylate donors, leaving the bridgehead nitrogen atom nonbonding. The calcium(II) ion in the monomeric complex 1 is distorted pentagonal-bipyramidal coordinated, the +1 charge of the complex cation [CaII(H2L)(OH2)4]+ is balanced by an H2L, anion and both units are connected by hydrogen bonds. The polymeric compound 2 displays a one-dimensional chain structure, in which two [CaII(L)]2, units form a dimeric structure and are connected by hydrated CaII ions. 3 contains two different [GdIII(L)(OH2)n] dimers. In one of them the two GdIII ions are linked by two monoatomic carboxylate O-bridges showing a short Gd···Gd distance of 3.99 Å. In the second, a syn - anti carboxylate 1,3-bridge with a longer Gd···Gd distance of 4.96 Å is observed. Magnetic measurements of 3 show paramagnetic behaviour with weak antiferromagnetic coupling. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Modes of Reactivity of Cyclic Diynes: Probing the syn/anti Selectivity of Tetrathiacycloalkadiynes and Mono(alkyne)cobalt ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2003Christoph Benisch Abstract Cyclic tetrathiaalkadiynes in which two 1,4-dithiaalkyne units are connected with alkane bridges of length n and m [A(m.n)] were treated with [,2 -bis(tert -butylsulfonyl)acetylene]carbonyl(,5 -cyclopentadienyl)cobalt(I) (8a) and several substituted analogues (8b,8e) in order to probe the reactivity of electron-rich cyclic diynes. Both mono- [B(m.n)] and bis(cyclobutadiene) [C(m.n)] complexes were isolated as products of these reactions and the anti/syn ratio of C(m.n) was determined. For m, n < 4 the syn isomers dominate and this is attributed to the configuration of the intermediate metallacycle which is correlated with the conformations of the rings in the mono(cyclobutadiene) products B(m.n). This analysis was corroborated by X-ray structural investigations of the products. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Mono- and Dimetallic Cyano Complexes with {Mo(,3 -allyl)(CO)2(N,N)} FragmentsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2003Julio Pérez Abstract Treatment of [MoCl(,3 -allyl)(CO)2(phen)] with NaCN in CH2Cl2/MeOH afforded [Mo(CN)(,3 -allyl)(CO)2(phen)] [allyl = C3H5 (1a); 2-MeC3H4 (1b)] as the sole products (no products of cyanide attack on the allyl group were detected). Treatment of 1a,b with [Mo(OTf)(,3 -C3H5)(CO)2(phen)] and NaBAr,4 in CH2Cl2 yielded the compounds [{Mo(,3allyl)(CO)2(phen)}(,-CN){Mo(,3 -C3H5)(CO)2(phen)}]BAr,4 (2a,b). Analogous treatment of 1a with fac -[M(OTf)(CO)3(bipy)] (M = Mn, Re) and NaBAr,4 resulted in the synthesis of [{Mo(,3 -C3H5)(CO)2(phen)}(,-CN){M(CO)3(bipy)}]BAr,4 (3, 4), in which the C and N atoms of the cyano bridge are bonded to Mo and M (M = Mn, Re), respectively. The linkage isomer of 4 (C and N atoms of the cyano group bonded to Re and Mo, respectively) (6) was prepared by treatment of [Re(CN)(CO)3(bipy)] (5) with [Mo(OTf)(,3 -C3H5)(CO)2(phen)] and NaBAr,4. Compounds 1a, 2b, 3, and 6 were characterized by X-ray diffraction. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Reactivity of (Mono- tert -butyloxiranyl)lithium: A Theoretical Ab Initio StudyEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 26 2008Abdelatif Bouyacoub Abstract The reactivity of the lithiated tert -butyloxiranyl anion has been studied by means of ab initio calculations at the CCSD(T)//MP2 level of theory. Four reaction paths have been studied (three ring-opening reactions and one addition reaction). All extrema were located and characterised. The effects of solvation by one or two MeLi molecules were studied for each reaction path by reoptimising the various extrema. It was found that the addition reaction path becomes competitive when at least two MeLi molecules are taken into account. This shows the catalytic effect of alkyllithium on this reaction path. In no case could a free carbene be characterised as a reaction intermediate. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Synthesis of New Sterically Hindered AnilinesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 19 2007Barry R. Steele Abstract Ring-alkylated primary, secondary and tertiary anilines have been ethylated with ethylene at benzylic positions in a simple and inexpensive one-pot procedure which is mediated bythe use of the superbase system nBuLi/LiK(OCH2CH2NMe2)2in the presence of Mg(OCH2CH2OEt)2. Primary and secondary anilines are ethylated readily at ortho -benzylic positions but with difficulty or not at all at other positions. Tertiaryanilines are ethylated at all positions. Mono- or diethylation occurs depending on the steric constraints present.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Electron-Transfer-Initiated Cascade Cyclizations of Terpenoid Polyalkenes in a Low-Polarity Solvent: One-Step Synthesis of Mono- and Polycylic Terpenoids with Various FunctionalitiesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2004Mustafa E. Ozser Abstract A methodology for the one-step synthesis of cyclic polyalkene terpenoids in a low-polarity solvent (dichloromethane) by photoinduced electron transfer (PET) is described. For the efficiency of such processes in low-polarity solvents, the use of the cationic electron acceptor N -methylquinolinium hexafluorophosphate is vital. The first direct cyclizations of farnesol and geranylgeraniol to the corresponding all- trans -fused 6,6- and 6,6,6-cyclic products are also reported. The mechanism of the termination of the cyclizations is also discussed, isotope-labeling experiments having shown that it proceeds through reduction of the final radical to the corresponding anion, followed by protonation. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Subsite specificity of trypanosomal cathepsin L-like cysteine proteasesFEBS JOURNAL, Issue 9 2001Probing the S2 pocket with phenylalanine-derived amino acids The S2 subsite of mammalian cysteine proteinases of the papain family is essential for specificity. Among natural amino acids, all these enzymes prefer bulky hydrophobic residues such as phenylalanine at P2. This holds true for their trypanosomal counterparts: cruzain from Trypanosoma cruzi and congopain from T. congolense. A detailed analysis of the S2 specificity of parasitic proteases was performed to gain information that might be of interest for the design of more selective pseudopeptidyl inhibitors. Nonproteogenic phenylalanyl analogs (Xaa) have been introduced into position P2 of fluorogenic substrates dansyl-Xaa-Arg-Ala-Pro-Trp, and their kinetic constants (Km, kcat/Km) have been determined with congopain and cruzain, and related host cathepsins B and L. Trypanosomal cysteine proteases are poorly stereoselective towards d/l -Phe, the inversion of chirality modifying the efficiency of the reaction but not the Km. Congopain binds cyclohexylalanine better than aromatic Phe derivatives. Another characteristic feature of congopain compared to cruzain and cathepsins B and L was that it could accomodate a phenylglycyl residue (kcat/Km = 1300 mm,1·s,1), while lengthening of the side chain by a methylene group only slightly impaired the specificity constant towards trypanosomal cysteine proteases. Mono- and di-halogenation or nitration of Phe did not affect Km for cathepsin L-like enzymes, but the presence of constrained Phe derivatives prevented a correct fitting into the S2 subsite. A model of congopain has been built to study the fit of Phe analogs within the S2 pocket. Phe analogs adopted a positioning within the S2 pocket similar to that of the Tyr of the cruzain/Z-Tyr-Ala-fluoromethylketone complex. However, cyclohexylalanine has an energetically favorable chair-like conformation and can penetrate deeper into the subsite. Fitting of modeled Phe analogs were in good agreement with kinetic parameters. Furthermore, a linear relationship could be established with logP, supporting the suggestion that fitting into the S2 pocket of trypanosomal cysteine proteases depends on the hydrophobicity of Phe analogs. [source] Effect of plantation design on stem-infecting form of rust in willow biomass coppiceFOREST PATHOLOGY, Issue 2 2002T. HUNTER Planting of genotype mixtures is a major strategy for the non-chemical control of willow rust in short-rotation coppice willows grown for biomass. In 1997 and 1998, the relative severity and spatiotemporal distribution of stem canker damage by Melampsora spp. on Salix viminalis `Bowles Hybrid' in a field trial containing monocultures and two design mixtures (random or regular) of three or five genotypes were assessed. Sphaerellopsis filum, a hyperparasite of Melampsora spp. was detected in all plots during the summer (1998) between the time of the two canker assessments. The percentage of rust pustules with this hyperparasite was initially greater in monoculture plantings than in mixtures in June, but by July, more than 92% of pustules were parasitized, irrespective of plantation design. The stem rust assessments showed that, in general, there were fewer cankers per stool in plots containing mixtures of willow genotypes compared with monoculture plantings. The distribution of rust cankers was different between monocultures and willow mixture designs, with differences between years for monocultures. Effet du type de plantation sur l'infection de la tige par la rouille, dans un taillis de saule Le mélange de clones constitue une stratégie majeure pour controler non chimiquement la rouille du saule dans les taillis à courte rotation en vue de la production de biomasse. En 1997 et 1998, on a évalué la gravité et la répartition spatio-temporelle du chancre de tige provoqué par Melampsora spp. sur Salix viminalis `Bowles Hybrid' dans un essai au champ comprenant des parcelles monoclonales ou deux types de mélange de 3 ou 5 clones (régulier ou aléatoire). Sphaerellopsis filum, un hyperparasite de Melampsora spp. a été détecté dans toutes les parcelles pendant l'été (1998) entre les deux dates d'évaluation du chancre. En juin, le pourcentage initial de pustules de rouille infectées par l'hyperparasite était plus élevé dans les parcelles monoclonales que dans les mélanges; en juillet, plus de 92% des pustules étaient parasitées, quel que soit le type de parcelles. L'évaluation de la rouille de tige a montré qu'en général il y avait moins de chancres par pied-mère dans les parcelles polyclonales que dans les parcelles monoclonales. La répartition des chancres de rouille était différente entre les parcelles mono et polyclonales; des différences existaient aussi entre les années dans les parcelles monoclonales. Der Einfluss des Pflanzschemas auf die Infektion mit Stammrost in Weidenplantagen Sortenmischung ist eine der besten Strategien zur biologischen Bekämpfung des Weidenrosts in Weiden-Energieholz-Plantagen mit kurzer Umtriebszeit. Mischkulturen mit drei oder fünf Genotypen, die nach einem zufälligen oder regelmässigen Muster angelegt wurden, sowie Monokulturen von Salix viminalis `Bowles Hybrid' wurden 1997 and 1998 auf das relative Schadensausmass und die räumlich-zeitliche Verteilung durch von Melampsora spp. verursachten Krebsen in Feldversuchen verglichen. Sphaerellopsis filum, ein Hyperparasit von Melampsora spp., wurde im Sommer 1998 in der Periode zwischen den beiden Erhebungsterminen in allen Versuchsflächen nachgewiesen. Im Juni war der Prozentsatz von Rostpusteln mit Hyperparasitenbefall in den Monokulturen höher als in den Flächen mit mehreren Genotypen, aber ab Juli waren unabhängig von der Kulturform > 92% der Pusteln parasitiert. Die Erhebungen zeigten, dass in Mischkulturen im Vergleich zu den Monokulturen im allgemeinen weniger Krebse pro Stock beobachtet wurden. Die Verteilung der Krebse in Mono- und Mischkulturen waren verschieden. Zudem wurden für die Monokulturen Unterschiede zwischen den beiden Jahren festgestellt. [source] Solution-Processible Phosphorescent Blue Dendrimers Based on Biphenyl-Dendrons and Fac -tris(phenyltriazolyl)iridium(III) Cores,ADVANCED FUNCTIONAL MATERIALS, Issue 19 2008Shih-Chun Lo Abstract Solution-processible saturated blue phosphorescence is an important goal for organic light-emitting diodes (OLEDs). Fac -tris(5-aryltriazolyl)iridium(III) complexes can emit blue phosphorescence at room temperature. Mono- and doubly dendronized fac -tris(1-methyl-5-phenyl-3- n -propyl-1H -[1,2,4]triazolyl)iridium(III) 1 and fac -tris{1-methyl-5-(4-fluorophenyl)-3- n -propyl-1H -[1,2,4]triazolyl}iridium(III) 4 with first generation biphenyl-based dendrons were prepared. The dendrimers emitted blue light at room temperature and could be solution processed to form thin films. The doubly dendronized 3 had a film photoluminescence quantum yield of 67% and Commission Internationale de l'Eclairage (CIE) coordinates of (0.17, 0.33). OLEDs comprised of a neat film of dendrimer 3 and an electron transport layer achieved a brightness of 142,cd m,2 at 3.8,V with an external quantum efficiency of 7.9%, and CIE coordinates of (0.18, 0.35). Attachment of the fluorine atom to the emissive core had the effect of moving the luminescence to shorter wavelengths but also quenched the luminescence of the mono- and doubly dendronized dendrimers. [source] Monitored Natural Attenuation of Manufactured Gas Plant Tar Mono- and Polycyclic Aromatic Hydrocarbons in Ground Water: A 14-Year Field StudyGROUND WATER MONITORING & REMEDIATION, Issue 3 2009Edward F. Neuhauser Site 24 was the subject of a 14-year (5110-day) study of a ground water plume created by the disposal of manufactured gas plant (MGP) tar into a shallow sandy aquifer approximately 25 years prior to the study. The ground water plume in 1988 extended from a well-defined source area to a distance of approximately 400 m down gradient. A system of monitoring wells was installed along six transects that ran perpendicular to the longitudinal axis of the plume centerline. The MGP tar source was removed from the site in 1991 and a 14-year ground water monitored natural attenuation (MNA) study commenced. The program measured the dissolved mono- and polycyclic aromatic hydrocarbons (MAHs and PAHs) periodically over time, which decreased significantly over the 14-year period. Naphthalene decreased to less than 99% of the original dissolved mass, with mass degradation rates of 0.30 per year (half-life 2.3 years). Bulk attenuation rate constants for plume centerline concentrations over time ranged from 0.33 ± 0.09 per year (half-life 2.3 ± 0.8 years) for toluene and 0.45 ± 0.06 per year (half-life 1.6 ± 0.2 years) for naphthalene. The hydrogeologic setting at Site 24, having a sandy aquifer, shallow water table, clay confining layer, and aerobic conditions, was ideal for demonstrating MNA. However, these results demonstrate that MNA is a viable remedial strategy for ground water at sites impacted by MAHs and PAHs after the original source is removed, stabilized, or contained. [source] Synthesis and Characterization of Copper Complexes Containing the Tripodal N7 Ligand Tris{2-[(pyridin-2-ylmethyl)amino]ethyl}amine (=N,-(Pyridin-2-ylmethyl)- N,N -bis{2-[(pyridin-2-ylmethyl)amino]ethyl}ethane-1,2-diamine): Equilibrium, Spectroscopic Data, and Crystal Structures of Mono- and Trinuclear Copper(II) ComplexesHELVETICA CHIMICA ACTA, Issue 9 2005Christian Gérard The stability constants of the CuII chelates with the tripodal heptadentate ligand tris{2-[(2-pyridylmethyl)amino]ethyl}amine (=N,-(pyridin-2-ylmethyl)- N,N -bis{2-[(pyridin-2-ylmethyl)amino]ethyl}ethane-1,2-diamine; tpaa), determined by potentiometry and UV spectrometry, show the formation of [Cu(tpaaH)]3+ and [Cu(tpaa)]2+ species. In the solid state, two mononuclear CuII compounds, [Cu(tpaa)](PF6)2 (1) and [Cu(tpaaH)](ClO4)3,H2O (2), and one trinuclear [Cu3(tpaa)2(ClO4)2](ClO4)4,2,H2O (3) complex were isolated and characterized by IR, UV/VIS, and EPR spectroscopy. An X-ray structure of the mononuclear protonated complex 2 shows that the Cu2+ ion has a distorted square-pyramidal geometry (,=0.21). and the proton is bound to the secondary-amine function of one uncoordinated arm of the tripod ligand (Fig.,4). The crystal lattice for 2 is stabilized by the H-bonds between the N-atom of the free pyridinyl group with the proton of the free secondary-amine function of the neighboring molecule. The linear trinuclear complex 3 consists of two entities of the pyramidal mononuclear complex 1 bound to the third central Cu2+ ion by the free unprotonated arms of the ligands in equatorial position (Fig.,5). The octahedral geometry of the third CuII atom is achieved by two perchlorate anions in the axial positions. The redox properties of 1,3 compounds was examined by cyclic voltammetry. [source] Silicon Surface-Bound Redox-Active Conjugated Wires Derived From Mono- and Dinuclear Iron(II) and Ruthenium(II) Oligo(phenyleneethynylene) Complexes,ADVANCED MATERIALS, Issue 10 2008Nicolas Gauthier Electron-rich mononuclear Fe(II) or dinuclear Fe(II)/Ru(II) acetylide complexes are photochemically grafted onto hydrogenated silicon surfaces following a simple and mild one-step procedure. The monolayers of redox-active organometallics that are formed exhibit efficient electrical communication between their bound metallic centers and the silicon surface through interfacial SiC bonds. [source] Glycosylation status of haptoglobin in sera of patients with prostate cancer vs. benign prostate disease or normal subjectsINTERNATIONAL JOURNAL OF CANCER, Issue 1 2008Tsutomu Fujimura Abstract We studied chemical level and glycosylation status of haptoglobin in sera of patients with prostate cancer, as compared to benign prostate disease and normal subjects, with the following results. (i) Haptoglobin level was enhanced significantly in sera of prostate cancer. (ii) Sialylated bi-antennary glycans were the dominant structures in haptoglobins from all 3 sources, regardless of different site of N-linked glycan. The N-linked glycans at N184 were exclusively bi-antennary, and showed no difference between prostate cancer vs. benign prostate disease. (iii) Tri-antennary, N-linked, fucosylated glycans, carrying at least 1 sialyl-Lewisx/a antenna, were predominantly located on N207 or N211 within the amino acid 203-215 sequence of the ,-chain of prostate cancer, and were minimal in benign prostate disease. Fucosylated glycans were not observed in normal subjects. A minor tri-antennary N-linked glycan was observed at N241 of the ,-chain in prostate cancer, which was absent in benign prostate disease. (iv) None of these N-linked structures showed the expected presence of disialylated antennae with GalNAc,4(NeuAc,3)Gal,3(NeuAc,6)GlcNAc,Gal, or its analogue, despite cross-reactivity of prostate cancer haptoglobin with monoclonal antibody RM2. (v) Minor levels of O -glycosylation were identified in prostate cancer haptoglobin for the first time. Mono- and disialyl core Type 1 O-linked structures were identified after reductive ,-elimination followed by methylation and mass spectrometric analysis. No evidence was found for the presence of specific RM2 or other tumor-associated glycosyl epitopes linked to this O -glycan core. In summary, levels of haptoglobin are enhanced in sera of prostate cancer patients, and the N -glycans attached to a defined peptide region of its ,-chain are characterized by enhanced branching as well as antenna fucosylation. © 2007 Wiley-Liss, Inc. [source] Iron-Catalyzed Oxidative Mono- and Bis-Phosphonation of N,N -DialkylanilinesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2010Wei Han Abstract The dehydrogenative ,-phosphonation of substituted N,N -dialkylanilines by dialkyl H -phosphonates was achieved under mild conditions by using environmentally benign iron(II) chloride as catalyst and tert -butyl hydroperoxide as oxidant. The reaction proceeded in the presence of electron-donating (methoxy, methyl, benzyl) and electron-withdrawing ring-substitutents (bromo, carbonyl, carboxyl, m -nitro) in moderate to good yields. The X-ray crystal structure of N -(5,5-dimethyl-2-oxo-2,5 -[1,3,2]dioxaphosphinan-2-yl-methyl)- N -methyl- p -toluidine was determined. Bis-(4-(dimethylamino)phenyl)methane and bis-4,4,-(dimethylamino)benzophenone underwent bisphosphonation selectively by respective monophosphonation at the remote dimethylamino groups. Furthermore, the use of excess dialkyl H -phosphonate and oxidant allowed us to functionalize both methyl groups of N(CH3)2 in N,N -dimethyl- p -toluidine and N,N -dimethylaminomesidine, respectively, to obtain ,,,,-bisphosphonatoamines in high yield. [source] Properties and Catalytic Activities of New Easily-Made Amphiphilic Phosphanes for Aqueous Organometallic CatalysisADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010Michel Ferreira Abstract Mono- and disulfonated amphiphilic versions of triphenylphosphane (PPh3) and cyclohexyl(phenyl)phosphane were easily synthesized from commercial reagents and sulfuric acid. The behaviour of these phosphanes in solution was investigated by surface tension, isothermal titration calorimetry, nuclear magnetic resonance and cryo-transmission electron microscopy. Two different supramolecular assemblies were evidenced according to the degree of sulfonation. The monosulfonated phosphanes formed well organized micelle-like aggregates while the disulfonated phosphanes formed heterogeneous and disorganized vesicle-like assemblies. The efficiency of these amphiphilic phosphanes was evaluated in the aqueous biphasic, palladium-catalyzed cleavage of allyl alkyl carbonates. [source] Resorcin[4]arene-Derived Mono- and Diphosphines in Suzuki Cross-CouplingADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2010Hani El Moll Abstract Three resorcin[4]arene cavitands (1,3) having either one or two resorcinolic C-2 atoms substituted by a CH2PPh2 podand arm were assessed in the Suzuki arylation of aryl bromides with phenylboronic acid. Using P:Pd ratios of 2:1 and operating in dioxane at 100,°C with a catalyst loading of 0.001,mol% resulted in highly efficient catalytic systems. For example, TOFs up to 34570 mol(converted ArBr),mol(Pd),1,h,1 were obtained with the proximally-disubstituted cavitand 3 when using 4-bromotoluene as substrate. The performance was shown to vary in the following order: monophosphine 1
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