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  • 1
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Carbene complexes ; Chromium ; Cyclophanes ; Chirality ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19971300812
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  • 2
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Chirality ; Chromium complexes ; Helicity ; Configuration (absolute) ; [2.2]Metacyclophanes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19921251130
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  • 3
    Digitale Medien
    Digitale Medien
    Deformierte chirale [n]Metacyclophane (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 759-765 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Chirality ; Circular dichroism ; Conformational mobility ; Cyclophanes ; [n]Phanes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270427
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  • 4
    Digitale Medien
    Digitale Medien
    Template synthesis of the first amide-based rotaxanes (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 739-743 
    Details
    ISSN: 0947-3440
    Schlagwort(e): Interlocked rings ; Macrocycles ; Mechanical bond ; Rotaxanes ; Template effect ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 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“.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.1995199505109
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  • 5
    Digitale Medien
    Digitale Medien
    Structure/Chiroptics Relationships of Planar Chiral and Helical Molecules (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1491-1509 
    Details
    ISSN: 1434-193X
    Schlagwort(e): Chirality ; Circular dichroism ; Cyclophanes ; Theoretical calculations ; Strained molecules ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Supramolecular chemistry ; Rotaxanes ; Mechanical bond ; Molecular recognition ; Chirality ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Amide-Based [3]Catenanes and [2]Catenanes with Aliphatic Chains (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 499-505 
    Details
    ISSN: 1434-193X
    Schlagwort(e): Catenanes ; Molecular recognition ; Template effect ; Mechanical bond ; Key-lock interaction ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---[3]Catenanes of the amide type were synthesized preparatively for the first time. Large macrocycles bearing two guest-binding sites were used to synthesize these amide-linked [3]catenanes in yields of 4%, either by formation of rigid macrocyclic boxes, or with macrocycles consisting of flexible long-chained aliphatic diamines. Furthermore, the systematic introduction of 1,ω-alkane diamines as building blocks for catenanes is described. The synthesis of a series of [2]catenanes by varying the ring size of one of the two macrocycles was also achieved in yields of 10%.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Azobenzene-Based Photoswitchable Catenanes (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 649-656 
    Details
    ISSN: 0947-3440
    Schlagwort(e): Catenanes ; Interlocked rings ; Mechanical bond ; Photoswitches ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Four catenanes (1-4) and the corresponding tetracationic monocycles 5-8 are synthesized. X-ray structural analyses allow a prediction of the mobility (circumrotation) of the „interlocked“ rings in the catenanes, which is proven by 1H-NMR spectroscopy. An unexpected order in the crystal packing of 6 is demonstrated. (E/Z) isomerization in one ring influences the second ring of 1-4 and inversely. An existing obstacle inside the cavity of the switchable macrocycle can block this isomerization completely.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.199519950491
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