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  • 1
    Electronic Resource
    Electronic Resource
    Metal Complexes with Macrocyclic Ligands. Part XXXIPart XXX: see [1].. Protonation studies and complexation properties of tetraazamacrocyclic methylenephosphonates with earth-alkali ions (1990)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 140-148 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The three ligands 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylenephosphonic acid) (1), 1,4,7,11-tetraazacyclotridecane-1,4,7,11-tetrakis(methylenephosphonic acid) (2), and 1,4,8,11-tetraazacyclotetradecane-1,4,8,1 1-tetrakis(methylenephosphonic acid) (3) have been synthesized by condensation of the corresponding macrocycles with formaldehyde and phosphorous acid. The protonation and stability constants with the earth-alkali ions have been determined at 25° and I = 0.1 M (Me4)N(NO3) by potentiometric titrations. Because of the high values of the first two protonation constants, 1H-NMR measurements were necessary to determine them. Titrations in different supporting electrolytes (NaNO3, KNO3, RbNO3, CsNO3, and Me4N(NO3)) show that their choice is of paramount importance, as the above ligands can form complexes with alkali-metal ions. The potentiometric results for the earth-alkali ions show that beside mononuclear complexes of different degrees of protonation ([MLHn], n = 0-4), also binuclear species are formed ([M2LHm], m = 0-2). It is interesting that 1 with the smallest macrocyclic ring has the greatest tendency to form binuclear complexes, which are so stable that they partially prevent the formation of the corresponding mononuclear species. For [ML], [MLH], [M2L], and [M2LH], the stability sequence is Mg2+ 〈 Ca2+ 〉 Sr2+ 〉 Ba2+, whereas for [MLH2], [MLH3], and [MLH4], the stability steadily decreases from Mg2+ to Ba2+.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19900730115
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  • 2
    Electronic Resource
    Electronic Resource
    Metal complexes of macrocyclic ligands. Part XXXVIIPart XXXVI: [1].. Synthesis of Heteroditopic Bis-macrocycles and Their Potential for Preparing Heterobinuclear Metal Complexes (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 23-35 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new and generally applicable synthetic path for the preparation of heteroditopic bis-macrocycles using tri-N-protected tetraazacycloalkanes as building blocks and bromoacetyl bromide as bridging reagent is described. In the first step, bromoacetyl bromide is used as acylating agent for one of the macrocycles, whereas in the second step it is used as alkylating agent for the second macrocycle, thus giving protected bis-macrocyclic amides (e.g. 6). After reduction of the amide moiety and deprotection, bis-azamacrocycles with an ethylene bridge are obtained (e.g. 8). The corresponding homoditopic bis-macrocycles 16 and 17 are also prepared for comparison purpose. Spectrophotometric studies indicate that bis-macrocycle 8, which consists of a 12- and a 14-membered ring, binds two metal ions with equal affinity, whereas compound 13, in which an unsubstituted (cyclam) and a trimethyl-substituted tetraazacyclotetradecane unit (Me3cyclam) are bridged, shows selective metal-ion binding. The first metal ion is always incorporated into the cyclam unit, whereas the second one binds to the Me3cyclam macrocycle. Thus, by sequential addition of two different metal ions, heterobinuclear complexes can easily be prepared. The electrochemistry of the binuclear Ni2+ complexes, studied by CV and DPV, as well as the EPR spectra of the binuclear Cu2+ complexes clearly indicate metal-metal interactions.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19940770105
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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 Macrocyclic Ligands. Part XXXIIPart XXXI, see [1].. Reactivity studies of the pendant carboxylic group in a macrocyclic Cu2+ complex towards amide formation and its use as a protein-labelling agent (1990)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 149-153 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Cu2+ complex of 1, having a non-coordinating carboxylic group, can be reacted under the typical conditions of peptide formation with amines such as 2-methylpropylamine or (pyrid-2-yl)methylamine to give, after removal of Cu2+ with CN-, the amides 4 and 5. The Cu2+ ion is of paramount importance since it protects the four amino groups of the macrocycle so that the amide condensation can specifically be done with the exogenous amine It is also shown that the Cu2+ complex of 1 can be covalently attached to bovine serum albumin (BSA), thus opening the possibility to use this compound as a labelling agent for proteins and antibodies.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19900730116
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  • 5
    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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  • 6
    Electronic Resource
    Electronic Resource
    Metal complexes with macrocyclic ligands. Part XXXVIPart XXXVI:[1].. Thermodynamic and kinetic studies of bivalent and trivalent metal ions with 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 383-398 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: NMR, potentiometric, and UV/VIS measurements were run to study the protonation and the In3+ and Cu2+ stability constants of 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (do3a, L). The protonation of do3a follows the typical scheme with two high and several low log KH values. Between pH 11 and 13, the protonation mainly occurs at the N-atom, which is not substituted by an acetate side chain. The In3+ complex is not appreciably protonated even at low pH values (pH ⋐ 1.7), whereas [CuL] can add up to three protons in acidic solution to give the species [CuLH], [CuLH2], and [CuLH3], the stability of which was determined. The formation rates of the Y3+, Gd3+, Ga3+, and In3+ complexes with do3a were measured using a pH-stat technique, whereas that of Cu2+, being faster, was followed on a stopped-flow spectrophotometer. In all cases, the reaction scheme implies the rapid formation of partially protonated intermediates, which rearrange themselves to the final product in the rate-determining process. ([MLH])in, an intermediate, in which the metal ion probably is coordinated by two amino acetate groups, proved to be the reactive species for Y3+, Gd3+, and Ga3+. The formation of [Cu(do3a)] was interpreted by postulating that either ([CuLH])in or ([CuLH])in, and ([CuLH2])in are the reactive complexes. The rates of dissociation of the Y3+, Gd3+, and Cu2+ complexes with do3a were studied spectrophotometrically. For Y3+ and Gd3+, arsenazo III was used as a scavenger, whereas for Cu2+ the absorption associated with d-d* transition was followed. For [Y(do3a)] and [Gd(do3a)], the rate law follows the kinetic expression kobsd = k0 + k1[H+]. The dissociation of [Cu(do3a)] goes through the proton-independent dissociation of [CuLH3], which is the main species at low pH.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19940770136
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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Metal complexes of macrocyclic ligands. Part XXXIIIPart XXXII:[1]. Effect of the side-chain length on the on/off equilibrium in the Ni2+ and Cu2+ complexes of 11-(2-aminoethyl)- and 11-(3-aminopropyl)-1,4,7,11-tetraazacyclotetradecane (1990)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 716-722 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkylation of 1,4,7-tritosyl-1,4,7,11-tetraazacyclotetradecane with CH2O/KCN or acrylonitrile gave the corresponding cyanomethyl or 2-cyanoethyl derivatives, which, by treatment with Na in BuOH, were detosylated and reduced to the macrocyclic pentaamines 1 and 2. The Ni2+ and Cu2+ complexes with 1 and 2 show a reversible pH-dependent change in geometry, in which the side-chain amino group is either coordinated to the metal ion (basic form) or protonated and, thus, non-coordinated (acidic form). The length of the side chain determines the log Ka values of these protonation/deprotonation equilibria: 1.89 and ∼ 2.0 for the Cu2+ and Ni2+ complexes of ligand 1 with the 2-aminoethyl side chain, and 6.17 and 7.43 for the Cu2+ and Ni2+ complexes of ligand 2 with the 3-aminopropyl side chain.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19900730320
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  • 9
    Electronic Resource
    Electronic Resource
    Survey of the DNA binding properties of natural and synthetic polyamino compounds (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 461-466 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Using a flourescence-detected ethidium displacement assay, the calf thymus DNA complexation properties of 27 mono-, di-, tri-, tetra- and hexacationic polyamines were determined. The DNA-binding affinity of these polyamine compounds increased with increasing cationic charge on the polyamine. Although most of the compounds exhibited no base pair binding selectivity, two of the tricationic polyamines possessing additional neutral amine groups exhibited approximately tenfold GC binding selectivities.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050807
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  • 10
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of the dissociation of the Cu2+ and Ni2+ complexes with monooxo- and dioxomacrocyclic tetraamines (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 549-555 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the acid-induced dissociation of the Ni2+ and Cu2+ complexes of a monooxo and two dioxo tetraaza macrocycles were studied by stopped-flow spectrophotometry at single wavelengths and using a photodiode array, For the monooxo derivative the dissociation rate follows the law vd = k1Ccom [H+]/(K2 + [H+]), whereas for the dioxo derivatives the law is vd = k2Ccom [H+]2/(K1 + K2 [H+] + [H+]2). The dissociation kinetics are interpreted by a mechanism in which protonated intermediates are formed in a rapid pre-equibrium, the rate-determining step being the dissociation of this species. Comparison of the spectral results from multi-wavelength stopped-flow measurements with those acquired in the equilibium study using spectrophotometric titrations allows the nature and structure of these intermediates to be discussed. The order of the dissociation rates in strongly acidic solution, where a plateau in the pH dependence is reached, was determined and it demonstrates the importance of the ring size on one hand and of the number of amide groups on the other.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050818
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