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  • 1
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1491-1509 
    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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  • 2
    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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  • 3
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 2115-2121 
    ISSN: 0947-3440
    Schlagwort(e): Cyclophanes ; Macrocycles ; Phanes ; Pyridinophanes ; Ring compounds ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 0947-3440
    Schlagwort(e): Catenanes ; Circumrotation ; Macrocycles ; Mechanical bonds ; Template syntheses ; Host-guest chemistry ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: New catenanes of the amide-linked type, such as 11 with one macrocycle containing two (CH2)12 chains are synthesized from long-chain alkanediamines in yields of up to 21%. Consequently, the preorganization afforded by fixed and angular building units - so far considered essential - proves not to be necessary. The new sulfonamide catenanes exhibit high conformational flexibility. However, the circumrotation of one of the macrocycles can be hindered by substitution with bipyridine units at the sulfonamide nitrogen.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 739-743 
    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
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  • 6
    ISSN: 0947-3440
    Schlagwort(e): Catenane synthesis ; Macrocycles ; Molecular recognition ; Sulfonamides ; Intertwining mechanism ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1097-1103 
    ISSN: 0009-2940
    Schlagwort(e): Bond formation, C-C ; Iron complexes ; Macrocycles ; Molecular tweezers ; Naphthalenophane ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Preorganized Bis-ethynes: Molecular π-Tweezers?1,8-Bis[(arylethynylphenyl)]naphthalenes of type V (e.g. 10, 11) and 1,8-bis[(arylethenylphenyl)]naphthalenes (6, 6a, 7, 7a) were synthesized for the first time. In contrast to the known 1,8-bis(arylethynyl)naphthalenes VI their “stereologs” 10 and 11 are thermally stabile. Yet they react with pentacarbonyliron to yield dinuclear transition metal complexes of the type 12, 13, i.e. a strained cyclophane macrocycle is formed by C-C bond formation. The X-ray analysis of the di-tert-butyl compound 11 shows that the peri substituents diverge, but with increasing distance from the naphthalene skeleton one of the arylethynyl units is bent to the opposite direction (Figure 2). The question whether the new molecular skeleton V can be viewed as molecular tweezers is discussed: as the hydrocarbons react irreversibly with transition metal carbonyls, they may rather be taken as “tweezers for single use”.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 671-672 
    ISSN: 0009-2940
    Schlagwort(e): Azines ; Bis(azines) ; Macrocycles ; Tetraazapolyenes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1675-1686 
    ISSN: 0009-2940
    Schlagwort(e): Azobenzene ; Concave dyes ; Dyes ; Isomerism, in-out ; Macrocycles ; Molecular switches ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Concave Dyes with Azobenzene Units as Chromophores, Photoswitchable and Cavity-Forming ElementsFive monomacrocyclic (12a-e) and three types of threefold azobenzene-bridged oligomacrocyclic compounds (15, 17, 28, 31) have been synthesized. Due to the cavity-forming chromophores at the periphery of these molecules they represent concave dyes. The watersoluble monocycles 12b-e were photoisomerized and investigated before and after E/Z isomerization with regard to their host properties for small neutral organic guest compounds. The bicyclic azobenzene derivative 31 with triphenylethane spacers exhibits in/out isomerism. The in/out isomer 31c was separated by HPLC from 31a and b, which are in equilibrium at room temperature. The tris(2-aminoethyl)amine-capped Schiff bases 15 and 17 form complexes with Cu(CH3CN)4BF4.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1881-1887 
    ISSN: 0009-2940
    Schlagwort(e): Heteraphanes ; Cyclophanes ; Macrocycles ; Tube-shaped molecules ; Phanes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: From Fourfold Functionalized Cyclophanes to Tube-Shaped MoleculesA series of fourfold functionalized 2,11-dithia- and 2,11-diaza[3.3]cyclophanes 15-17 and 18-22, resp., is prepared by using a new multistep-strategy starting from 7 or m-xylene, respectively. The cyclophanes are used to construct tube-shaped molecules of type 24 by macrocyclization reactions of e. g. 21 and 22. Macrocycle 24 turns out to be conformationally flexible.
    Materialart: Digitale Medien
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