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  • 1
    Electronic Resource
    Electronic Resource
    Komplexierung von Blei(II) durch Azakronenether und Kryptanden in Methanol (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3408-3412 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexation of Lead(II) by Aza Crown Ethers and Cryptands in MethanolThe stability of PbII complexes with the mono- and bicyclic ligands 1 - 5 in methanol was determined by potentiometric titrations using an ion-selective lead(II) electrode. Reaction enthalpies ΔH were measured by calorimetric titrations. Substitution of the protons at the nitrogen atoms of aza crown 1b by the long decyl chains in 1d leads to a great increase in ΔH, whereas the complex stability is scarcely influenced. Benzo anellands (3, 4) reduce the ligand flexibility and cause a decrease in reaction enthalpies. The reaction entropies are nearly unchanged.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180837
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  • 2
    Electronic Resource
    Electronic Resource
    Stabilitätskonstanten und thermodynamische Werte für die Bildung von 1:1- und 2:1-Komplexen von Kronenethern mit Alkali- und Erdalkali-Ionen in Methanol (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2746-2756 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stability Constants and Thermodynamic Values for the Formation of 1:1- and 2:1-Complexes of Crown Ethers with Alkali and Alkaline-earth Ions in MethanolThe determination of stability constants and thermodynamic values for the reaction of crown ethers with alkali-, alkaline-earth ions, and the silver ion was achieved by calorimetric titration in methanol. Through modification of the experimental conditions it is possible to measure separately the formation of 1:1- and 2:1-complexes (ratio of ligand to cation). With the exception of Ag+ and Ca2+ all ions examined form both kinds of complexes with the various 15 C 5 ligands. The complex stabilities are influenced by enthalpic and entropic contributions. 18 C 6 and DC 18 C 6, having a bigger diameter than 15 C 5, show a definite increase of the stability of 1:1-complexes. Only the Cs+ ion with the largest radius forms 2:1-complexes. A good agreement is found with values determined potentiometrically for the 1:1- and 2:1-complex formation of Na+.
    Notes: Die Komplexstabilitäten und thermodynamischen Werte für die Reaktion von Kronenethern mit Alkali-, Erdalkali-Ionen und dem Silber-Ion in Methanol wurden mittels kalorimetrischer Titrationen bestimmt. Durch Veränderung der experimentellen Bedingungen ist es möglich, sowohl die Bildung von 1:1- als auch 2:1-Komplexen (Verhältnis von Ligand zu Kation) getrennt voneinander zu messen. Mit Ausnahme von Ag+ und Ca2+ bilden alle untersuchten lonen beide Arten von Komplexen mit den verschiedenen 15 K 5-Liganden. Die Komplexstabilitäten werden von enthalpischen und entropischen Faktoren beeinflußt. 18 K 6 und DC 18 K 6, die einen größeren Durchmesser als 15 K 5 besitzen, zeigen einen deutlichen Anstieg der Stabilität der 1:1-Komplexe. 2:1-Komplexe bildet nur noch das Cs+ -Ion mit dem größten Radius. Ein Vergleich mit potentiometrisch bestimmten Daten für die 1:1- und 2:1-Komplexbildung von Na+ zeigt gute Übereinstimmung.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180717
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  • 3
    Electronic Resource
    Electronic Resource
    Synthese und Komplexbildung eines neuen makrocyclischen Liganden mit drei Benzimidazolin-2-on-Einheiten (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2483-2485 
    Details
    ISSN: 0009-2940
    Keywords: Macrocyclic ligand ; Benzimidazolin-2-one ; Complexation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Complex Formation of a New Macrocyclic Ligand Incorporating Three Benzimidazolin-2-one Units The new macrocyclic ligand 1 composed of three benzimidazolin-2-one-1,3-diyl and three propane-1,3-diyl building blocks has been synthesized. Complex formation constants in water involving Li+, Na+, K+, Mg2+ Ca2+, Si2+, and Ba2+ are discussed. The most stable complex is formed with Ca2+.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251121
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  • 4
    Electronic Resource
    Electronic Resource
    all-Homocalixarene: Carbocyclische Wirtverbindungen mit intra- und extraannularen Ligandarmen (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2483-2491 
    Details
    ISSN: 0009-2940
    Keywords: Carbocycles ; Homocalixarenes ; Calixarenes, Homo- ; Large rings ; Macrocycles ; [2n]Metacyclophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: all-Homocalixarenes: Carbocyclic Host Compounds with Intra- and Extraannular Ligand ArmsMethoxy-substituted [2n]metacyclophanes 1-10, obtained by Müller-Röscheisen cyclization, are converted into all-homocalixarenes 11-20 with free phenolic hydroxy functions. The well-soluble cyclic pentamer 11 and octamer 14 with endo-acidic host properties are investigated with regard to guest binding. They exhibit selectivity towards alkaline earth metal ions (Ba2+) in liquid/liquid extraction studies. Some of the macrocyclic oligophenols are transformed into homocalixarenes 21-25 with intra- or extraannular oxapropionate groups. The diester 22 and the tetraester 23 are converted into carbocycles 26 and 27 with two and four free oxapropionic acid groups. Complexation properties of the oligoesters in extraction studies and log K values in water are reported. X-ray structural analyses were performed of the [6]-, [8]- and [4]- homocalixarenes 9 and 21, 14 and 23; the inclusion of solvent molecules is proven.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261123
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  • 5
    Electronic Resource
    Electronic Resource
    Unusual Complexation Behavior of Metallomacrocycles Based on Isothiosemicarbazides with Respect to Alkali and Alkaline Earth Metal Ions: Novel 2:1 Associates (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 1089-1093 
    Details
    ISSN: 0009-2940
    Keywords: Metallomacrocycles ; Nickel complexes ; Complexation reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions between alkali and alkaline earth metal ions and nickel(II) macrocycles based on S-alkylated isothiosemi-carbazides with different crown ether cavity size were studied in propylene carbonate by spectrophotometric and calorimetric titrations. Metallomacrocycles 1 and 2 exhibit normal behavior on 1:1 complexation with alkali- and alkaline earth metal ions and resemble in this respect 15C5 and 18C6, respectively. The most stable complexes are formed by these “ligands” when the diameter of the cation and the crown ether hole have approximately the same size. The most striking feature of the complexation processes studied is the formation of 1:2 metal-ligand associates even in the case of the smallest cations. These associates are very different from “normal” crown ether sandwich complexes. In reality, the particle formed is an associate between a 1:1 complex, in which the corresponding metal ion is well accommdated inside the ligand cavity, and a second metallomacrocyclic ligand. Their formation is disfavored by enthalpic contributions. A special kind of “switch” from these associates to normal sandwich complexes takes place in the case of 1, when the cation diameter compared to hole size increases. The macrocycle 2 forms this kind of associates with all akali and alkaline earth ions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951281106
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  • 6
    Electronic Resource
    Electronic Resource
    Komplexierung von AgI durch Kronenether mit unterschiedlichen Donoratomen und strukturell variierten Kryptanden in Methanol (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 4297-4302 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Complexation of AgI by Crown Ethers with Different Donor Atoms and Structural Varied Cryptands in MethanolThe complex stability of AgI with mono- and bicyclic ligands 1-6 was measured by potentiometric titrations in methanol. The reaction enthalpies were estimated by means of calorimetric titrations. All examined monocyclic ligands not only containing oxygen as donor atoms form - with one exception - more stable complexes than crown ethers. Ligands with a cavity too small for Ag+ ions are able to complex the cation with a ratio of ligand to cation of 2:1. Reducing the cavity size of cryptands by benzo anellands (4, 5) leads to a small decrease in complex stability. Other structural changes at the bicyclic ligands do not influence the complex formation.
    Notes: Die Komplexstabilität von AgI mit mono- und bicyclischen Liganden 1-6 wurde durch potentiometrische Titrationen in Methanol gemessen. Mit Hilfe kalorimetrischer Titrationen wurden die Reaktionsenthalpien bestimmt. Alle monocyclischen Liganden, die neben Stickstoff auch Sauerstoff und Schwefel als Donoratome enthalten, bildeten - mit einer Ausnahme - stabilere Komplexe als reine Kronenether. Liganden, deren Durchmesser kleiner ist als der von Ag+, sind in der Lage Komplexe zu bilden, deren Zusammensetzung Ligand zu Kation 2:1 ist. Die Verkleinerung des Hohlraumes der Kryptanden durch Benzo-Anellanden (4,5) führt nur zu einer kleinen Abnahme der Komplexstabilität. Andere strukturelle Veränderungen an den bicyclischen Liganden beeinflussen die Komplexbildung nicht.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851181102
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