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Amine Ligands (amine + ligand)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

New Chiral Amine Ligands in the Desymmetrization of Prochiral Phosphine Boranes.

CHEMINFORM, Issue 14 2005
Magnus J. Johansson
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Synthesis and Characterization of CuII Complexes with Amino Acid Substituted Di(2-pyridyl)amine Ligands

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2007
ko I. Kirin
Abstract The two-step syntheses of the substituted di(2-pyridyl)amine ligands (dpa), dpa-CH2CO2H (1) and dpa-PhCO2H (2), are described. Ligands 1 and 2 are successfully coupled to the amino acid phenylalanine, yielding the derivatives 4 and 6, respectively. Four CuII(dpa)2 complexes, [Cu(dpa-CH2CO2tBu)2(NO3)2] (3Cu), [Cu(dpa-CH2CO-PheOMe)2(H2O)2](NO3)2·2MeOH (4Cu), [Cu(dpa-PhCO2Me)2 (MeOH)2](ClO4)2 (5Cu) and [Cu(dpa-PhCO-PheOMe)2(ClO4)2] (6Cu) have been prepared and characterized, including their single crystal X-ray structures. Fluorescence emission at UV (for 3 and 4) or blue (for 5 and 6) wavelengths of the free ligands is preserved in the corresponding Cu complexes, although with lower intensity. X-band EPR spectra of 4Cu and 6Cu both revealed one axial CuII signal with hyperfine and superhyperfine splittings. Complexes 4Cu and 6Cu are chiral inorganic complexes with amino acid bioconjugates that may serve as nucleoside analogs in modified peptide nucleic acids (PNA). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Solution NMR and X-Ray Structural Studies on Phthalocyaninatoiron Complexes

HELVETICA CHIMICA ACTA, Issue 8 2006
Ignacio Fernández
Abstract The addition of primary amines as solubilizing reagents for phthalocyaninatoiron complexes is shown to afford six-coordinate bis(amine)phthalocyaninato complexes, i.e., [Fe(amine)2(pc)] 2 (amine,=,decan-1-amine) and 3 (amine,=,benzylamine), with the two new N-donors occupying the trans -axial positions. The new complexes were characterized by extensive NMR measurements in THF solution. For complex 3 with the benzylamine ligand, the solid-state structure was determined by X-ray diffraction methods. Complex 2 is sufficiently labile in THF solution to exchange one amine ligand against CO (gas) affording an equilibrium mixture containing [Fe(amine)(CO)(pc)] 4. [source]

Copper Complexes with Neutral N4 Tripodal Ligands: Influence of the Number of Nitrogen Donors on Their Structures, Properties, and Reactivity,

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 26 2009
Kiyoshi Fujisawa
Abstract Copper coordination complexes of the neutral tetradentate nitrogen-containing ligands tris(3,5-dimethylpyrazol-1-ylmethyl)amine (L0N4) and tris(3,5-diisopropylpyrazol-1-ylmethyl)amine (L1N4), namely the copper(II) chlorido complexes [CuII(L0N4)Cl2] (1) and [CuII(L1N4)Cl2] (2), the copper(II) nitrato complexes [CuII(L0N4)(NO3)](NO3) (3) and [CuII(L1N4)(NO3)](NO3) (4), and the copper(II) sulfato complexes [CuII(L0N4)(SO4)] (5) and [CuII(L1N4)(SO4)] (6), and the copper(I) complexes [CuI(L0N4)](PF6) (7) and [CuI(L0N4)(PPh3)](ClO4) (8), have been systematically synthesized in order to investigate the influence of the number of nitrogen donors on their structures, properties, and reactivity. All copper(II) complexes were fully characterized by X-ray crystallography and by IR/far-IR, UV/Vis absorption, and ESR spectroscopy. Although the structure of 7 was not determined by X-ray crystallography, this complex and the structurally characterized copper(I) triphenylphosphane complex 8 were fully characterized by IR/far-IR and NMR spectroscopy. A comparison of the copper(II) complexes with two tris(pyrazol-1-ylmethyl)amine ligands with different bulkiness of the pyrazolyl rings has allowed us to evaluate the second coordination sphere effects of the ligands. Moreover, the structures and physicochemical properties of these complexes are compared with those of related complexes containing the neutral tridentate tris(pyrazolyl)methane ligand and the neutral bidentate bis(pyrazolyl)methane ligand. Finally, the relative stability of the copper(I) complexes is discussed. The influence of the number of nitrogen donors in copper complexes is observed from these systematic results.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

Synthesis and Characterization of CuII Complexes with Amino Acid Substituted Di(2-pyridyl)amine Ligands

Synthesis of Polyamines from Ethylenediamine and Their Platinum(II) Complexes, Potential Antitumor Agents

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2006
Mara Rubia Costa Couri
Abstract This work describes the synthesis and characterization of five new amine ligands and also the preparation and characterization of their respective platinum(II) complexes by reaction with K2PtCl4 in water. These ligands were obtained by treatment of different halides or epoxides with ethylenediamine. Cytotoxic activity and cellular accumulation of three complexes were investigated in a human small-cell lung carcinoma cell line and its cisplatin resistant subline. The introduction of a spacer (cycle) between the two platinum atoms leads to a significant decrease in cytotoxic activity. At equitoxic doses, the intracellular platinum concentrations found for compounds 12 and 15 were significantly higher than those found for the reference compounds, cisplatin, carboplatin, or compound 9. This fact suggests that the formation of adducts between compounds 12 and 15 and the putative pharmacological target, DNA, is less favored. If these compounds bind more slowly to DNA, interaction with other intracellular ligands such as sulfur-containing molecules will become relevant and it may be the reason for the elevated intracellular platinum concentrations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Discrete Cyanide-Bridged Mixed-Valence Co/Fe Complexes: Outer-Sphere Redox Behaviour

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2003
Paul V. Bernhardt
Abstract The outer-sphere redox behaviour of a series of [LnCoIIINCFeII(CN)5], (Ln = n -membered pentadentate aza-macrocycle) complexes have been studied as a function of pH and oxidising agent. All the dinuclear complexes show a double protonation process at pH , 2 that produces a shift in their UV/Vis spectra. Oxidation of the different non-protonated and diprotonated complexes has been carried out with peroxodisulfate, and of the non-protonated complexes also with trisoxalatocobaltate(III). The results are in agreement with predictions from the Marcus theory. The oxidation of [Fe(phen)3]3+ and [IrCl6]2, is too fast to be measured, although for the latter the transient observation of the process has been achieved at pH = 0. The study of the kinetics of the outer-sphere redox process, with the S2O82, and [Co(ox)3]3, oxidants, has been carried out as a function of pH, temperature, and pressure. As a whole, the values found for the activation volumes, entropies, and enthalpies are in the following margins, for the diprotonated and non-protonated dinuclear complexes, respectively: ,V, from 11 to 13 and 15 to 20 cm3 mol,1; ,S, from 110 to 30 and ,60 to ,90 J K,1 mol,1; ,H, from 115 to 80 and 50 to 65 kJ·mol,1. The thermal activation parameters are clearly dominated by the electrostriction occurring on outer-sphere precursor formation, while the trends found for the values of the volume of activation indicate an important degree of tuning due to the charge distribution during the electron transfer process. The special arrangement on the amine ligands in the isomer trans -[L14CoIIINCFeII(CN)5], accounts for important differences in solvent-assisted hydrogen bonding occurring within the outer-sphere redox process, as has been established in redox reactions of similar compounds. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Formation of molecular radical cations of aliphatic tripeptides from their complexes with CuII(12-crown-4)

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2004
Ivan K. Chu
Molecular radical cations have proven to be difficult to generate from aliphatic peptides under electrospray ionization mass spectrometry (ESI-MS) conditions. For a family of small aliphatic peptides GGX, where XG, A, P, I, L and V, these cations have been generated by electrospraying a mixture of Cu.2+, 12-crown-4 and GGX in methanol/water. GGX.+ is readily formed from the collision-induced dissociation (CID) of [CuII(12-crown-4)(GGX)].2+. The formation of these aliphatic peptide radical ions from these complexes, in cases where it is not possible from the corresponding complexes involving a series of amine ligands instead of 12-crown-4, is likely due to the second ionization energy of the [CuI(12-crown-4)(GGX)]+ complex being higher than that of the corresponding [CuI(amine)(GGX)]+ complex. Using these 12-crown-4 complexes, GGI can be differentiated from the isomeric GGL by comparing the CID spectra of their [a3+H].+ ions. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Long-chain silanes as reducing agents part 1: a facile, efficient and selective route to amine and phosphine-stabilized active Pd-nanoparticles

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 3 2010
Bhanu P. S. Chauhan
Abstract Recently, metal nanoparticles have found applications in various fields, which have necessitated exploration of new avenues to obtain such materials. In this publication, a hydrosilane-based reduction and characterization of resulting palladium nanoparticles is achieved using palladium acetate as nanoparticle precursor and octadecylsilane as a reducing agent. The influence of phosphine and amine ligands in the stabilization of nanoparticles is also investigated. In addition, a brief mechanistic proposal of the reduction process is also discussed. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Palladium(0) pre-catalysts with heteroditopic NHC,amine ligands by transmetallation from their silver(I) complexes

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 6 2009
Stefan Warsink
Abstract The synthesis of an air-stable series of Pd0 complexes with dissymmetric bidentate N -heterocyclic carbene,amine ligands has been performed. The key step is an unprecedented carbene transfer from AgI to obtain electron-rich zero-valent palladium precatalysts. The coordination behavior of the ligands was determined with X-ray crystallography. Surprising results were obtained in the catalysis of transfer semi-hydrogenation, where the addition of base appeared not to be necessary to obtain the desired product stereoselectively. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Unique Properties of DNA Interstrand Cross-Links of Antitumor Oxaliplatin and the Effect of Chirality of the Carrier Ligand

CHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2008
Jana Kasparkova Dr.
Abstract The different antitumor and other biological effects of the third-generation antitumor platinum drug oxaliplatin [(1R,2R -diamminocyclohexane)oxalatoplatinum(II)] in comparison with those of conventional cisplatin [cis -diamminedichloridoplatinum(II)] are often explained by the ability of oxaliplatin to form DNA adducts of different conformation and consequently to exhibit different cytotoxic effects. This work describes, for the first time, the structural and biochemical characteristics of the interstrand cross-links of oxaliplatin. We find that: 1),DNA bending, unwinding, thermal destabilization, and delocalization of the conformational alteration induced by the cross-link of oxaliplatin are greater than those observed with the cross-link of cisplatin; 2),the affinity of high-mobility-group proteins (which are known to mediate the antitumor activity of platinum complexes) for the interstrand cross-links of oxaliplatin is markedly lower than for those of cisplatin; and 3),the chirality at the carrier 1,2-diaminocyclohexane ligand can affect some important structural properties of the interstrand cross-links of cisplatin analogues. Thus, the information contained in the present work is also useful for a better understanding of how the stereochemistry of the carrier amine ligands of cisplatin analogues can modulate their anticancer and mutagenic properties. The significance of this study is also reinforced by the fact that, in general, interstrand cross-links formed by various compounds of biological significance result in greater cytotoxicity than is expected for monofunctional adducts or other intrastrand DNA lesions. Therefore, we suggest that the unique properties of the interstrand cross-links of oxaliplatin are at least partly responsible for this drug's unique antitumor effects. [source]