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  • 1
    ISSN: 0947-3440
    Keywords: Catenane synthesis ; Macrocycles ; Molecular recognition ; Sulfonamides ; Intertwining mechanism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first catenanes containing sulfonamide units were synthesized. Selective formation of the in/out isomer 7 can be explained by host-guest interactions that cause a regioselective templating effect. Replacement of O2S-NH by O2S-NMe increases the yield significantly (from 10 to 19%). The sulfonamide catenane 7 has a topologically chiral structure.
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  • 2
    ISSN: 0570-0833
    Keywords: Host-guest chemistry ; Onium compounds ; Clathrates ; Inclusion compounds ; Macrocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The importance of organic onium compounds for host/guest interactions in biological processes has been long recognized. In contrast, the versatility of synthetic onium compounds as host molecules in abiotic chemistry has only been investigated in detail for the last few years. Due to their inclusion ability and selectivities, organic ammonium, pyridinium, and phosphonium salts and other organic salts with specific structural features are interesting as clathrate-forming molecules. The crystal structures of the clathrates afford insight into the conformational adaptability of onium clathrands with limited flexibility to the geometric requirements of the guest molecules. Optically active onium hosts can be used for enantiomeric enrichment. In crystalline tetracyanoquinodimethane(TCNQ) complexes and radical anion salts, the structure of the organic heterocation has a marked effect on the electrical conductivity. Macrocyclic onium compounds of the phane type with “exohydrophilic” and “endolipophilic” cavities are suitable as models of enzymes and biological receptors. They can also be used to transfer aromatic and aliphatic guest molecules selectively into aqueous solution. Catalytic activity (including H/D exchange) has already been obtained with synthetic compounds having large cavities. The further development of such host/guest systems may contribute to the understanding of biological systems and the improvement of technical processes (catalysis in molecular cavities).
    Additional Material: 22 Ill.
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  • 3
    ISSN: 0570-0833
    Keywords: catenanes ; macrocycles ; mechanical bonds ; rotaxanes ; template synthesis ; Catenanes ; Macrocycles ; Mechanical binding ; Rotaxanes ; Template synthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: After Sauvage et al. and Stoddart et al. had developed the now commonly used and well-established catenane and rotaxane synthesis utilizing phenanthroline/Cu+ and bipyridinium/crown units, a new way to synthesize mechanical bonds was discovered in 1992 - the synthesis of amide-linked catenanes and rotaxanes around a neutral template. The formation of the template, which leads to the host-guest bond, does not proceed by covalent or ionic interaction, but by weak supramolecular interactions, such as hydrogen bonding, π-stacking, π-donor-π-acceptor interaction, and steric complementarity. The simple synthetic units (arene dicarboxylic acid dichlorides and diamines) can be varied in an astonishing number of ways, few steps are required to obtain the target molecules, and the yields of these syntheses approach those of ordinary organic syntheses. After the preparation of [2]catenanes, it took only a few years to prepare [2]-, [3]-, and bis[2]-rotaxanes of the amide type. The introduction of sulfonamide groups enabled alkylation of the sulfonamide nitrogen atom, and this made chemical reactions with catenanes and rotaxanes feasible. Intra- and intermolecular connections of catenanes and rotaxanes were then possible, and a molecule with the topology of a “pretzel” has recently been prepared. This allowed new insights into the molecular recognition processes of neutral guest and host substances, as well as further understanding of these processes in template synthesis, isomerism in catenanes, and the regioselectivity of the formation of catenane isomers. Competitive binding studies of guest molecules in the cavity of concave receptors with more than one binding site can be perfomed. These studies might result in higher synthetic yields of molecules with mechanical bonds and lead to further progress in the development of supramolecular nanostructures and molecular switches.
    Additional Material: 32 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0009-2940
    Keywords: Azines ; Bis(azines) ; Macrocycles ; Tetraazapolyenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new macrocyclic bis(azine) 2 forming yellow microcrystals has been prepared in 72% yield by treating the diketone 1 with hydrazine hydrate under high-dilution conditions. In contrast to the UV/Vis spectrum of the “open-chain” azine 4, that of 2 shows characteristic features of a polyene chromophore containing (Z)-configurated double bonds.
    Additional Material: 1 Ill.
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  • 5
    ISSN: 0009-2940
    Keywords: Biphenylophane ; Kharasch coupling reaction ; Macrocycles ; TCNQ ; TTF ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecules of the TTF and TCNQ Type with Macrocyclic SkeletonsThe electron-rich and electron-poor macrocycles 1 - 3 have been synthesized. Their [1.1](3,3′)biphenylophane framework is formed by Kharasch reaction. Whereas in the well-known donors and acceptors I-III the functionalities are conjugated, in their macrocyclic “analogues” 1-3 the conjugation is prevented by the meta-connection of the phenylene rings. The redox properties  - studied by cyclovoltammetry  -  are discussed. The X-ray analysis of 3 shows considerable deviations from a planar structure.
    Additional Material: 5 Ill.
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  • 6
    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.
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  • 7
    ISSN: 0009-2940
    Keywords: Concave molecules ; Cyclophanes ; High-dilution principle ; Macrocycles ; Spheriphanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Concave MacroheterocyclesMacrocyclic compounds of the general type 2 having a spherical shape and a molecular cavity have been synthesized. A „fold and paste“-type cyclization step generates the macroheterocycles 4, 10, 11, 14, and 21. Since this approach is difficult to apply for O-substituted derivatives, the „spheriphane“ 24 was synthesized by intermolecular cyclizaiton. The X-ray structure analysis of 11 shows intermolecular interactions („dimer formation“) in the crystal.
    Additional Material: 5 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0009-2940
    Keywords: Cyclohexanes ; Cyclohexanones ; Cyclophanes ; Macrocycles ; Paracyclophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Way to Macrocyclic para-PhenylenesStrategies are presented to synthesize the hitherto unknown [On]Paracyclophanes 1. Open chain belt-type molecules based on 1,4-connected carbocyclic six-membered rings were prepared. Functionalization of the outer rings in 4-position is the prerequisite for cyclization or lengthening of the molecular belts. In order to obtain the macrocyclic target molecules 1, well preorganized cis-isomers of 1,4-disubstituted cyclohexanes were prepared. X-ray structural analyses reveal the static stereochemistry of the intermediates 8, 9, 17, 18, and 24. The macrocyclic hydrocarbon 29 containing five cyclohexylidene units was detected.
    Additional Material: 3 Ill.
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  • 9
    ISSN: 0947-3440
    Keywords: Cyclophanes ; Macrocycles ; Phanes ; Pyridinophanes ; Ring compounds ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first synthesis of the ribbon-like compounds 6-10 is described. The new building block diethyl 2,6-bis(bromomethyl)pyridine-3,5-dicarboxylate 1 was prepared and characterized. Single-crystal X-ray structure analyses indicate that these ribbon-like molecules arrange in a folded conformation, with the pyridine and benzene units being folded in a face-to-face manner, and the tosyl units of 8-10 pointing outwards. The “intramolecular self-assembly” (folding) of these molecular ribbons is primarily attributable to the energetically more favourable syn conformation of both the [3.3]metacyclophanes and the pyridinophanes.
    Additional Material: 6 Ill.
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  • 10
    ISSN: 0947-3440
    Keywords: Interlocked rings ; Macrocycles ; Mechanical bond ; Rotaxanes ; Template effect ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first rotaxanes 6a, 6b and 11 with an amide structure are described. Their (supramolecular template) syntheses are strikingly simple. The central part of the „axle“ is added to the „wheel“ and subsequently capped. The macromonocycle („wheel“) provides the receptor cavity for the „axle“ and the triphenylmethane stoppers confirm the mechanical bond between „wheel“ and „axle“.
    Additional Material: 3 Ill.
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