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  • Chirality  (5)
  • Rotaxanes  (5)
  • macrocycles  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Nanometre-sized Macrocyclic Oligoamides by Iterative Synthesis (2000)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 37 (2000), S. 309-329 
    Details
    ISSN: 1573-1111
    Keywords: large rings ; nanocycles ; paracyclophanes ; macrocycles ; sulfonamides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract New nanometre-sized macrocyclictosylaza[3n]paracyclophanes have been synthesized bymeans of an iterative synthetic strategy using linearbuilding blocks with up to four benzene units. Theformation of the open-chain difunctionalized linearmolecules was achieved by a three step reactionsequence including nucleophilic substitution andtransformation of the terminal ester groups to thecorresponding dialcohol and dibromide. The finalintermolecular macrocyclizations were carried out byreaction of open chained dibromides andbis(tosylamides) to obtain nanosize macrocyclicoligotosylamides in 31–50% yield. Highly symmetricaltosylaza[3n]paracyclophanes containing up to sevenbenzene units and up to 49 ring members (n = 5–7) wereobtained. Also described is the preparation of30–90-membered paracyclophanes containing biphenyl orterphenyl units.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008174220437
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  • 2
    Electronic Resource
    Electronic Resource
    Chiral Metal Carbene Modified [2.2]Metacyclophanes: Synthesis, Structure, and Chiroptic Properties (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1105-1111 
    Details
    ISSN: 0009-2940
    Keywords: Carbene complexes ; Chromium ; Cyclophanes ; Chirality ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pentacarbonyl(4-[2.2]metacyclophanyl(methoxy)carbene)-chromium(0) (6) was prepared according to the Fischer route from 4-bromo[2.2]metacyclophane. Aminolysis with non-chiral and chiral amines affords aminocarbene complexes 7-12. X-Ray structure analyses for 6 and its aminocarbene analogs 7 and 8 indicate that the incorporation of the chromium-carbene fragment has no significant influence on the deformation of the [2.2]metacyclophane skeleton.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300812
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  • 3
    Electronic Resource
    Electronic Resource
    Tricarbonylchrom-Komplexe von chiralen [2.2]Metacyclophanen: Darstellung, Struktur und chiroptische Eigenschaften (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2553-2569 
    Details
    ISSN: 0009-2940
    Keywords: Chirality ; Chromium complexes ; Helicity ; Configuration (absolute) ; [2.2]Metacyclophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tricarbonylchromium Complexes of Chiral [2.2]Metacyclophanes: Syntheses, Structures, and Chiroptical PropertiesHPLC-baseline separations of three racemic cyclophanes 3, 4, and 6 on cellulose tris(3,5-dimethylphenyl)carbamate led to their enantiomers with high optical purity. Complexation of (-)-3 and (+)-3 with triamminetricarbonylchromium yielded chiral Cr(CO)3 complexes (-)-(S)P-(3S)M-3a and (+)-(R)P-(3R)M-3a stereoselectively. Derivatisation of the complexes by lithiation and reaction with electrophiles gave new substituted chiral Cr(CO)3 complexes of [2.2]metacyclophanes regio-selectively. X-ray structure analyses of one chiral chromium complex (-)-(R)P-(5S)M-14a and three chiral chromium-free ligands (-)-(S)P-3, (-)-(S)P-4, and (-)-(S)P-6 led to the assignment of the absolute configurations of all chiral compounds discussed here. The influences of substituents on the chiroptical properties are investigated. The helicity of [2.2]metacyclophanes is discussed. For the first time X-ray structure analyses were performed of a bis-Cr(CO)3 complex (9a) as well as of the first chromium complex 10a of a heteraphane. Dethioketalisation of (-)-(S)P-3 with NBS gave (-)-(S)P-18, the absolute chirality of which has been known, under retention of configuration.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251130
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  • 4
    Electronic Resource
    Electronic Resource
    Deformierte chirale [n]Metacyclophane (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 759-765 
    Details
    ISSN: 0009-2940
    Keywords: Chirality ; Circular dichroism ; Conformational mobility ; Cyclophanes ; [n]Phanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Deformed Chiral [n]MetacyclophanesThe new dithiametacyclophane 3c and the thiaazametacyclophanes 6a, b are chiral, but do not contain chirality centres. They are obtained by cyclization of 1,3-propanedithiol (2), or of the thiaza precursors 5a, b, with the bis(bromomethyl) compounds 1, 4a, b. The dynamic behaviour of the aliphatic chains in 3c, and 6a, b (flipping/rotation) have been studied by dynamic NMR. X-ray analyses of 3c and 6a document the out-of-plane deformation of the boat-shaped benzene ring. The circular dichroism of enantiomer-enriched 3c is reported.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270427
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  • 5
    Electronic Resource
    Electronic Resource
    Chemical Reactions in the Axle of Rotaxanes - Steric Hindrance by the Wheel (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1233-1238 
    Details
    ISSN: 1434-193X
    Keywords: Electrophilic additions ; Bromine addition to double bonds ; Hydrogenation of double bonds ; Rotaxanes ; Supramolecular chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Here we report on the possibility of using rotaxane wheels as noncovalent protecting groups which significantly decrease the activity of functional groups in the central part of the axle. The amide-linked rotaxanes 5aand 5b, each containing a C=C double bond in their axle, have been synthesised. The catalytic hydrogenation of these two rotaxanes proceeds slower than those of the corresponding free axle compounds 6a and 6b, indicating steric hindrance of the C=C double bond by the wheel of the rotaxane in each case. Nontheless, the rotaxane 9with an aliphatic (succinic acid) middle region in its axle can be prepared in this manner. Dehydrobromination of the axle in the rotaxane 15yields the rotaxane 16 with a C≡C triple bond located in the centre of the axle.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Template synthesis of the first amide-based rotaxanes (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 739-743 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1995199505109
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  • 7
    Electronic Resource
    Electronic Resource
    Rotaxanes with Chiral Stoppers and Complexation of Cations by Podand Axles with Sugar Terminal GroupsDedicated to Professor S. Hünig on the occasion of his 75th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 495-499 
    Details
    ISSN: 0947-3440
    Keywords: Ligand ; Metal complexation ; Podand ; Sugar stopper ; Supramolecular chemistry ; Rotaxanes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new π-donor/π-acceptor type rotaxanes 15, 16 bearing chiral sugar units as blocking groups have been synthesized in 2% and 6% yield, starting from acetobromo glucose 10 and the podands 8 or 9, followed by the reaction of the resulting axles 11 and 12 with the dicationic bis(bipyridinio) wheel precursor 13 and the bis(bromomethyl) compound 14. The capability of the podands 11 and 12 and of the rotaxanes 15 and 16 to form podate-like complexes with metal salts was investigated by NMR; the effect of metal thiocyanate salt addition was monitored. Distinct changes of proton shifts that indicate complex formation were only observed between the free axles 11, 12 and the metal salts, whereas no major effects were found in case of the rotaxanes 15, 16. Glucose entities were chosen as stopper units in order to support metal complexation as terminal groups and to introduce a source of chirality into the molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970309
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  • 8
    Electronic Resource
    Electronic Resource
    Structure/Chiroptics Relationships of Planar Chiral and Helical Molecules (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1491-1509 
    Details
    ISSN: 1434-193X
    Keywords: Chirality ; Circular dichroism ; Cyclophanes ; Theoretical calculations ; Strained molecules ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chiroptical properties of planar-chiral and helical molecules without stereogenic centres and with well-defined structure, strain, electronic properties and chirality are investigated by experimental and theoretical circular dichroism spectroscopy. We report on the synthetic and theoretical achievements made during the past 10 years in the field of rigid [2.2]metacyclophane propellers, as well as in the area of [n]para- and [n]metacyclophanes containing aliphatic parts like adamantane or unsaturated bridges. Results for carbo and hetero helicenes and helicene-related molecules like twisted phenanthrenes are presented. It is demonstrated how reliable theoretical calculations using configuration interaction and time-dependent methods in combination with density functional theory today are and how useful the interplay between theory and experiment stimulates the development of chiral molecules optimized for this purpose. Even for large molecules it is routinely possible to assign Cotton effects to electronic transitions, to evaluate chromophore contributions, to determine absolute configurations and conformational equilibria, and to discover intramolecular charge transfer effects.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Chiral Amide Rotaxanes with Glucose Stoppers - Synthesis, Chiroptical Properties and Wheel-Axle Interactions (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 2003-2007 
    Details
    ISSN: 1434-193X
    Keywords: Supramolecular chemistry ; Rotaxanes ; Mechanical bond ; Molecular recognition ; Chirality ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper we report on amide rotaxanes with tetrabenzoylglucose stoppers. When acetyl groups are used instead of benzoyl groups, merely a pseudo-rotaxane 5 is obtained. The circular dichroism measurements of the rotaxanes 6a and 6b differ significantly from that one of the free axle 7. Similarly, the Cotton effects of the mixtures of achiral wheels 2a and 2b and chiral axle indicate intermolecular host-guest interactions, likewise. After an addition of a solution of NaOMe the wheel is slipping off immediately and quantitatively by hydrolysis, as the benzoylglucose stoppers decrease in size by hydrolysis.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    A [3]rotaxane of the amide type (1996)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 2 (1996), S. 640-643 
    Details
    ISSN: 0947-6539
    Keywords: lactam ; macrocycles ; rotaxanes ; self-assembly ; template syntheses ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new rotaxane types, the [2]rotaxanes 12a,b and the [3]rotaxane 13, have been synthesised by treating the “axle” 7 with the stopper component 9 in the presence of the “wheel” 8. A nonionic template intermediate of type 10 is proposed. The [3]rotaxane 13 was only obtained when the chain of the “axle” had a certain length: with n = 1 only [2]rotaxane 12 a was isolated, whereas with n = 2 the [3]rotaxane 13 was formed besides the [2]rotaxane 12 b. This suggests that more extended rotaxanes and polyrotaxanes can be synthesised by the template strategy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.1460020605
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