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  • 1
    Electronic Resource
    Electronic Resource
    Influence of ligand structure and solvent effects on complexation of neutral guests by several crown ethers (1994)
    Springer
    Journal of solution chemistry 23 (1994), S. 53-61 
    Details
    ISSN: 1572-8927
    Keywords: Crown ethers ; benzocrown ethers ; non-charged complexes ; host-guest complexes ; calorimetric titration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The formation of complexes between crown ethers and acetonitrile, chloroform, and nitromethane were investigated in carbon tetrachloride at 25°C. A significant influence of the ring size on the selectivity of the host is evident. The host 18-crown-6 forms complexes for which the reaction enthalpy and entropy are quite high. Host molecules with benzene side groups form complexes of lower reaction enthalpy and entropy and therefore the complexes formed are less stable than that of the analogous crown ethers without aromatic groups. Solvent effects on the stability constant K, the reaction enthalpy ΔH, and the reaction entropy ΔS were studied for the complexation of malonitrile by 18-crown-6. The reaction enthalpy and entropy values change in accordance with the dielectric constant of the solvent used, but no overall effect on complex stability with change in solvent dielectric constant was observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00972607
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  • 2
    Electronic Resource
    Electronic Resource
    Liquid membrane transport of supramolecular complexes of some amines and amino acids with macrocyclic ligands (1995)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 23 (1995), S. 167-174 
    Details
    ISSN: 1573-1111
    Keywords: Amines ; amino acids ; liquid membrane ; macrocyclic ligands ; active transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The transport of some amines in protonated form was studied (viz. methylamine, dimethylamine, diethylamine andn-propylamine) and α-amino acids (l-leucine,l-methionine,l-isoleucine,l-phenylalanine,l-valine,l-α-alanine andl-cysteine). The following macrocyclic ligands were used as carriers throughout the experiments: 15-crown-5 (15C5), 18-crown-6 (18C6), benzo-18-crown-6 (B18C6), dibenzo-18-crown-6 (DB18C6), diazacrown ether [2.2] (1,7,10,16-tetraoxa-4,13-diazacyclooctadecane) and cryptand [2.2.2] (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo [8.8.8] hexacosane). The active transport, assisted by pH gradient, of amino acids and amines in protonated form as ion pairs in the presence of picrate anion was performed. The experiments suggested the influence of the ligand size, the donor atom type, and the substituents on the transport phenomena.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00709574
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  • 3
    Electronic Resource
    Electronic Resource
    Modifizierung von Faseroberflächen durch die permanente Fixierung supramolekularer Komponenten, Teil 1: GrundlagenAuszug aus der eingereichten Dissertation von U. Denter, Universität Duisburg 1997. (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 153-163 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: A new conception for modification of textile surfaces by permanent fixation of supramolecular components is explained. The principle of selective complexation is illustrated. Cyclodextrins, aza crown ethers, calixarenes, cyclotriveratrylenes and fullerenes are mainly suggested as suitable ligands for that procedure. The chemical structure and the complexation behaviour of the substances are described. Some surface properties which may be obtained with the ligands are especially emphasized.
    Notes: Ein neues Konzept zur Modifizierung von Faseroberflächen durch permanente Fixierung supramolekularer Verbindungen wird vorgestellt, und das Prinzip der selektiven Komplexierung wird erklärt. Als für die Behandlung grundsätzlich geeignete Liganden werden insbesondere Cyclodextrine, Azakronenether, Calixarene, Cyclotriveratrylene und Fullerene hinsichtlich ihrer chemischen Struktur sowie ihrer komplexierenden Eigenschaften beschrieben. Einige erreichbare Oberflächeneffekte werden hervorgehoben.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052480110
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  • 4
    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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  • 5
    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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  • 6
    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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  • 7
    Electronic Resource
    Electronic Resource
    The Complexation of Amino Acids by Crown Ethers and Cryptands in Methanol (1998)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 30 (1998), S. 21-28 
    Details
    ISSN: 1573-1111
    Keywords: Amino acids ; crown ethers ; cryptands ; complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Complex formation between several crown ethers and the cryptand (222) and α-amino acids in methanol was studied by calorimetric titration. The ligand structure and the donor atoms of the ligands play an important role in determining the measured values of the reaction enthalpies and entropies. However, with the exception of the diaza crown ether (22) all stability constants are of the same order of magnitude. The enthalpic and entropic contributions to the stabilities of the complexes formed compensate each other. In methanolic solution the amino acids exist in their zwitterionic form. This equilibrium can be influenced. Under acidic, neutral or basic conditions different values of the reaction enthalpies are measured for the complexation of some amino acids with 18-crown-6. These results demonstrate that the concentration of the zwitterionic form of the α-amino acids can be influenced. Thus the reaction between macrocyclic and macrobicyclic ligands and amino acids should be described by at least two different reaction schemes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007941023186
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  • 8
    Electronic Resource
    Electronic Resource
    Zum Einfluß von arylständigen Substituenten auf die Komplexbildung von Monobenzokronenethern mit Alkalimetallionen in Methanol und Aceton (1994)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 336 (1994), S. 5-10 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Influence of Aryl-bonded Substituents on Complex Formation of Benzocrown Ethers with Alkali Metal Ions in Methanol and Acetone SolutionsThe influence of aryl-bonded substituents upon the complex formation of monobenzocrown ethers towards alkali metal ions in methanol and acetone solutions are investigated by using calorimetric and potentiometric titration. A different complexation behaviour of the ligands in acetone and methanol was found. In the case of the 1:1 complexation of Na+ a correlation between substiuent effects and stability constants in acetone was noticed, however, the influence of substituents upon complex stability is weak. In methanol solutions no similar correlation could be established. During sandwich complexation of K+ in methanol, no significant substituent influences on K1 and K2 were observed. On the other hand, a considerable increase of ΔH2 for both the electron accepting and electron releasing substituents was found, probably caused by changes in ligand-cation solvation due to the substituents.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19943360103
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  • 9
    Electronic Resource
    Electronic Resource
    Modifizierung von Faseroberflächen durch die permanente Fixierung supramolekularer Komponenten, Teil 2: CyclodextrineAuszug aus der Dissertation von U. Denter, Universität Duisburg (eingereicht). (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 165-188 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Cyclodextrin derivatives may be fixed permanently onto different fibre surfaces by suitable functional groups using conventional technologies of textile processing. As a result of the modification process the properties of the polymers are influenced. Some examples are discussed in detail. For several ligands it is illustrated that the fixed cavities do not lose their complexing power. Thus, special functional properties can be obtained by the inclusion of specific active agents.
    Notes: Mit herkömmlichen Verfahrenstechniken der Textilveredlung werden ausgewählte Cyclodextrinderivat über geeignete funktionelle Gruppen permanent auf verschiedenen Fasermaterialien fixiert. Einige der durch die Oberflächenmodifizierung beeinflußten Eigenschaften der Polymeren werden im einzelnen diskutiert. Insbensondere kann für mehrere Liganden gezeigt werden, daß die verankerten molekularen Hohlräume nicht die Fähigkeit verlieren, hydrophobe organische Verbindungen zu komplexieren. Somit lassen sich durch den Einschluß spezifischer Wirksubstanzen spezielle funktionelle Eigenschaften erzielen.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052480111
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis of mono-, oligo- and polyamide-cucurbituril rotaxanesDedicated to Prof. Hartwig Höcker on the occasion of his 60th birthday (1998)
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 19 (1998), S. 59-63 
    Details
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mono-, oligo- and polyamide rotaxanes with the macrocycle cucurbituril are synthesized easily with high yields by interfacial condensation. The complex of cucurbituril with 1,6-hexanediammonium ion is used as preorganized structure. With different acid and diacid chlorides a great variety of amiderotaxanes and polyrotaxanes can be synthesized. The characterization is difficult due to the low solubility of cucurbituril and rotaxanes. But with the methods of IR, DTA, 1H NMR and elemental analyses, the existence of the rotaxanes is shown.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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