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  • 1
    Electronic Resource
    Electronic Resource
    Metal Complexes with Macrocyclic Ligands. Part XXVIIPart XXVI. Cu2+-promoted hydrolysis of carboxylic- and phosphonic-acid esters in the side chain of tetraazamacrocycles (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 131-138 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The X-ray structures of the Cu2+ complexes of 1,4,8,11-tetraazacyclotetradecane derivatives with an ethylpro-pionate and diethylphosphonate group, 5 and 6, respectively, indicate that the metal ion is pentacoordinated by the four N-atoms of the macrocycle and one O-atom. In the case of 5, it is the carbonyl O-atom of the carboxylate group, whereas for 6 it is the phosphonyl O-atom of the phosphonate group. The hydrolysis kinetics of the functional group in the Cu2+ complexes with the 1,4,8,11-tetraazacyclotetradecanes 3-6 have been measured by pH-stat and stopped-flow techniques. The rate law for the hydrolysis of the carboxylates 3-5 is proportional to the complex concentration and to [OH-] up to pH 13, whereas that of the phosphonate 6 is proportional to [OH-] up to pH 11.5, becoming independent of [OH-] at pH 〉 11.5. The mechanisms of these two reactions are discussed, considering the possibility of an intra- or an intermolecular OH- attack and the results of the X-ray structure analyses.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720117
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  • 2
    Electronic Resource
    Electronic Resource
    Metal complexes of macrocyclic ligands. Part XXIIIPart XXII: [1].. Synthesis, properties, and structures of mononuclear complexes with 12- and 14-membered tetraazamacrocycle-N,N′,N″,N‴-tetraacetic Acids (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 2067-2073 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The two tetraazamacrocycle-N,N′,N″,N‴-tetraacetic acids H4dota and H4teta form with Ni2+, Cu2+, and Zn2+ (M2+) mononuclear complexes MLH2 and M′[ML], M′ being an alkaline earth ion. The structures of Ni(H2dota) and Cu(H2dota) have been solved by X-ray structure analysis. The metal ions are in a distorted octahedral geometry coordinated by four amino N-atoms and two carboxylates. In the case of Cu2+, the distortions are more pronounced than for Ni2+ indicating that the Jahn-Teller effect is operating. Starting from these two structures, the coordination geometry of the other complexes is discussed using VIS and IR spectra.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690830
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  • 3
    Electronic Resource
    Electronic Resource
    Metal complexes with macrocyclic ligands. Part XXXIVPart XXXIII: [1].. Geometrical and conformational changes during the on/off reaction of the side chain in the CuII complex of 11-(3-aminopropyl)-1,4,7,11-tetraazacyclotetradecane (1991)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 74 (1991), S. 1689-1696 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solution studies of the Cu2+ complex with 11-(3-aminopropyl)-1,4,7,11-tetraazacyclotetradecane(L) indicate that, depending on the pH and on the age of the solution, different species are present. Dissolving the solid [CuL](ClO4)2 in slightly acidic solution gives the protonated complex AH, characterized by an absorption maximum at 574 nm, by a relatively fast proton-induced dissociation kinetics and by the typical colour change in basic solution to give the deprolonated form A with coordinated side chain. AH slowly interconverts in acidic solution to a new species BH, which has an absorption maximum at 547 nm, and which is kineticaily more stable against acid dissociation and shows no coordination of the amino group of the side chain. In alkaline solution, however, the deprotonated form B deliver A in a base induced reaction. The X-ray diffraction studies of A and BH allow to determine the geometry of the metal ion and the configuration of the macrocycle. In A, the Cu2+ is pentacoordinated by the five N-atoms of the ligand and the macrocycle is in the RRSR configuration, whereas in BH the Cu2+ is octahedrally coordinated by the four N-atoms of the macrocycle and two axial perchlorate O-atoms with the macrocycle in the RRRS configuration. The amino group of the side chain is protonated and not coordinated. Thus, the on/off equilibrium of the side chain not only changes the geometry of the metal ion, as is generally found, but also alters the macrocyclic moiety.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19910740809
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  • 4
    Electronic Resource
    Electronic Resource
    Metal Complexes with Macrocylclic Ligands. Part XXXVPart XXXIV: [1].. Stabilities of some bivalent metal-ion complexes with 1,4,7-triazacyclononane-1-acetie acid (1993)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 557-562 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stability constants of the Mn2+, Zn2+, Ni2+, pb2+, and Cd2+ complexes with 1,4,7-triazacylononane-1-acetic acid (noma) were determined at 25° and 0.5M (KNO3) by potentiometric titrations. The species [ML] and [ML(OH)] were found in al cases except for Ni2+, whereas [ML2] was only detected for Cd2+. For the complexes [ML], the order of stability is Mn2+ 〈 Cd2+ 〈 pb2+ 〈 Zn2+ 〈 Zn2+ 〈 Ni2+ 〈 Cu 2+, which is consisten with the Irvin-Williams Series.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19930760137
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis of Benzazepine Analogues of Noscapine (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 1590-1594 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of benzazepine analogues of the opium alkaloid noscapine (1) is described. The benzazepines 2 and 3 were prepared starting from nornarceine ethyl ester (4; readily available from 1) in several steps. X-Ray analysis of compound 2 revealed that it is not a diastereosisomer mixture but a racemate of the threo-form and thus has the same configuration as 1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19940770615
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  • 6
    Electronic Resource
    Electronic Resource
    Metal Complexes with Macrocyclic Ligands. Part XXXIXPart XXXVIII:[1].. Mono- and binuclear copper(II) complexes of a bridging bis[1, 4, 7-triazacyclononane] (1995)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 78 (1995), S. 693-702 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new bis-macrocycle 1, 1′-[(1H-pyrazol-3], 5-diyl)bis(methylene)bis[1, 4, 7-triazacyclononane] (1) was synthesized and its complexation with Cu2+ studied. Potentiometric and spectrophotometric titrations indicate that, in addition to the mononuclear species [Cu(LH2)]4+, [Cu(LH)]3+, [CuL]2+, and [Cu(LH-1)]+, binuclear complexes such as [Cu2L]4+, [Cu2(LH-1)]3+, and [Cu2(LH-2)]2+ are also formed in solution. The stability constants and spectral properties of these are reported. The binuclear species [Cu2(LH-1)]3+ specifically reacts with an azide ion to give a ternary complex [Cu2(LH-1)(N3)]2+, the stability and structure of which were determined spectrophotometrically and by X-ray diffraction, respectively. The two Cu2+ ions are in a square-pyramidal coordination geometry. The axial ligand is one of the N-atoms of the 1, 4, 7-triazacyclononane ring, whereas at the base of the square pyramid, one finds the other two N-atoms of the macrocycle, one N-atom of the pyrazolide and one of the azide, both of which are bridging the two metal centres. In [Cu2(LH-1)(N3)]2+, a strong antiferromagnetic coupling is present, thus resulting in a species with a low magnetic moment of 1.36 B.M. at room temperature.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19950780316
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  • 7
    Electronic Resource
    Electronic Resource
    Metal Complexes with Macrocyclic Ligands. Part XL.Part XXXIX: [1]. Syntheses and silver(I) complexes of mono- and disubstituted dithiadiazamacrocycles (1995)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 78 (1995), S. 1325-1333 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of N2S2-macrocycles with ring sizes varying between 12 and 16, as well as two 12-membered N2S2-rings with a pendant carboxylic and amino group, respectively, were synthesized. Their complexation properties towards Ag+ were studied by pH titrations and by potentiometry with a silver electrode. The observation that 1:1 ([AgLH2]3+, [AgLH]2+, [AgL]+) and 1:2 species ([AgL2H2]3+, [AgL2H]2+, [AgL2]+) were formed is interpreted by postulating that Ag+ can bind either to the S-donors only, or to both the N- and S-atoms. The most stable complex [AgL]+ in the series of the nonfunctionalized macrocycles was found for the 12-membered N2S2-ring 3. The stability of it increased when an additional donor group was introduced into the side chain. The highest formation constant (logβ110 = 14.43(1)) was obtained with the 12-membered ring 12 carrying the ethanamine side chain. In view of a radiochemical application, all Ag+ complexes were tested in blood serum for their stability, but were not stable enough against transmetallation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19950780522
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  • 8
    Electronic Resource
    Electronic Resource
    Metal Complexes with Macrocyclic Ligands. Part XLIPart XL: [1].. Nickel(II) and copper(II) complexes with mono-N-functionalized dithiadiazamacrocycles (1996)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 79 (1996), S. 235-243 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three N2S2 macrocycles (3, 10, 12) carrying an amino group as a pendant arm have been synthesized and their complexation properties towards Ni2+ and Cu2+ studied. The crystal structures of the Cu2+ complexes with 10-methyl-1,4-dithia-7,10-diazacyclododecane-7-ethanamine (3) and 11-methyl-1,4-dithia-8,11-diazacyclotetradecane-8-ethanamine (10) show that, in both cases, the Cu2+ is pentacoordinated by the four donor atoms of the macrocycle and the amino group of the side chain. In aqueous solution, however, two forms of the complexes with stoichiometries [MLH] and [ML] (M = Cu2+ or Ni2+) have been observed. In [MLH], the amino group is protonated and does not bind to the metal ion, whereas in [ML] the amino group is bound, and a pentacoordinated geometry results. The pKa values for the equilibrium [ML] + H+⇌[MLH]+ decrease in the order 12 〉 10 〉 3, indicating that the 2-aminoethyl side chain binds better to the Cu2+ than the 3-aminopropyl side chain. Cyclic voltammetry for the Cu2+/Cu+ pair shows that the 2-aminoethyl pendant arm stabilizes the Cu2+ oxidation state, when the metal ion is in the 14-membered ring (10), whereas it stabilizes Cu+ for the 12-membered macrocycle (3).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19960790124
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  • 9
    Electronic Resource
    Electronic Resource
    Metal Complexes with Macrocyclic Ligands. Part XLIIIPart XLII [1]. Tetraazamacrocyclic nickel(II) and copper(II) complexes with aliphatic methylthio- and methoxy-substituted pendant chains (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 241-252 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 14-membered tetraazamacrocyclic Ni2+ and Cu2+ complexes of 4 (1, 4, 8-trimethyl-11-[(2-methylthio)ethyl]-1, 4, 8, 11-tetraazacyclotetradecane), 5. (1, 4-dimethyl-8, 11-bis[2-(methylthio)ethyl]-l, 4, 8, 11-tetraazacyclotetradecane), and 7 (1, 4, 8, ll-tetrakis[2-(methylthio)ethyl]-1, 4, 8, 11-tetraazacyclotetradecane), with pne, two, and four methylthio-substituted pendant chains, respectively, and the Ni2+ complex of 6 (1, 4-dimethyl-8, 11-bis (2-methoxyethyl)-1, 4, 8, 11-tetraazacyclotetradecane), with two methoxy-substituted pendant chains, were synthesized and their chemistry studied with regard to modelling F430. Solution spectra in H2O, MeCN, and DMF indicate participation of the side chain in metal coordination when the donor group is a thioether, whereas no coordination with the metal ion is observed with the ether group. Similarly the X-ray structures of the thioether-containing compounds [Ni(5)](ClO4)2, [Cu(5)](ClO4)2, and [Cu(7)](ClO4)2 show a coordination number of 5, whereas that of [Ni(6)](ClO4)2 with ether pendant chains, shows a coordination number of 4. Cyclic voltammetry of these complexes in MeCN reveals that Ni2+ is reversibly reduced to Ni+ between -0.64 and -0.77 V vs. SCE, the potential being influenced by the nature and number of the pendant chains. At more negative potentials, the thioether is cleaved, whereby a thiol is formed; the thiol is then oxidized at ca. + 0.8 V vs. SCE, when a glassy carbon electrode is used, or at ca. 0 V vs. SCE at a dropping Hg electrode. No cleavage of the ether bond in [Ni(6)](ClO4)2 is observed under similar conditions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800122
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  • 10
    Electronic Resource
    Electronic Resource
    Comparison of the Complexation of Open-Chain and Cyclic N2S2 Ligands with Cu+ and Cu2+ (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1216-1223 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complexation properties of the open-chain N2S2 ligands 1-4 are described and compared to those of analogous N2S2 macrocycles 5-7. With Cu2+, the open-chain ligands give complexes with the stoichiometry CuL2+ and CuLOH+, the stabilities and absorption spectra of which have been determined. The ligand field exerted by these ligands is relatively constant and independent of the length of the chain. With Cu+, the species CuLH23+, CuLH2+, and CuL+ were identified and their stabilities measured. The redox potentials calculated from the equilibrium constants and measured by cyclic voltammetry agree and lie between 250 and 280 mV against SHE. The comparison between open-chain and cyclic ligands shows that (1) a macrocyclic effect is found for Cu2+ but not for Cu+, (2) the ligand-field strength is very different for the two types of ligands, and (3) the redox potentials span a larger interval for the macrocyclic than for the open-chain complexes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690529
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