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  • General Chemistry  (172)
  • Template synthesis  (5)
  • Helical molecules  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Templat-Synthese makrobicyclischer Großhohlräume vom Tris(bipyridin)-Typ (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1725-1727 
    Details
    ISSN: 0009-2940
    Keywords: Cryptands ; Macrobicyclic ligands ; Template synthesis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Template Synthesis of Macrobicyclic Large Cavities of the Tris-(bipyridine)-TypeThe synthesis of the ligands 2 and 3 has been performed in a one-step procedure starting with the triamines 11 and 12 and 5,5′-bis(bromomethyl)-2,2′-bipyridine (6). The new macrobicyclic compounds were isolated and characterized as their sodium complexes. Dynamic 1H-NMR investigations reveal the conformational flexibility of the complex 2 · Na⊕.
    Notes: Die Liganden 2 und 3 wurden in einer Eintopf-Synthese ausgehend von den Triaminen 11 und 12 sowie 5,5′-Bis(brommethyl-2,2′-bipyridin (6) erhalten und als Natrium-Komplexe isoliert und charakterisiert. Die dynamische 1H-NMR-Spektroskopie des Komplexes 2 · Na⊕ belegt seine konformative Beweglichkeit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220920
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  • 2
    Electronic Resource
    Electronic Resource
    Helicale und planarchirale Pyridinophane - Neue Synthesemethodik und Struktur-Chiroptik-Beziehungen (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 347-355 
    Details
    ISSN: 0009-2940
    Keywords: Circular dichroism ; Helical molecules ; [2.2]Metacyclophanes ; Oxa[2.2]metacyclophane ; [2.2]Pyridinophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Helical and Planar-chiral Pyridinophanes - A New Synthesis and Structure/Chiroptic RelationshipsA new two-step synthesis for the strained helical oxa[2.2]phanes 1-5 and for a systematic series of novel structural isomeric (2,4)-pyridinophanes (6-10) is presented. The energy barriers for ring inversion of some intermediate [3.2]phanes and the kinetics of racemization of the [2.2]phanes are determined. Separation and enrichment of enantiomers is achieved by HPLC on cellulose tris(3,5-dimethylphenyl)carbamate and poly(triphenylmethylmethacrylate), resp. The circular dichroism curves of the isomers are compared with those of the corresponding protonated pyridinium compounds. The influence of the chromophor orientation on the circular dichroism is discussed.
    Notes: Eine neue Zweistufensynthese zu den stark ringgespannten, helicalen Oxa[2.2]phanen 1-5 und eine systematische Reihe neuer strukturisomerer (2,4)-Pyridinophane (6-10) werden vorgestellt. Die Energiebarrieren für die Ringinversion der intermediären [3.2]Phane und die Racemisierungskinetik der [2.2]Phane werden gemessen. Racematspaltungen bzw. -anreicherungen gelingen durch HPLC and Cellulose-tris(3,5-dimethylphenyl)carbamat und Poly(triphenylmethyl-methacrylat). Die Circulardichroismen der strukturisomeren Zehnringe und der protonierten Pyridinium-Verbindungen werden gemessen. Die Auswirkung der Chromophor-Orientierung auf den Circulardichroismus wird vergleichend erörtert.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220224
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  • 3
    Electronic Resource
    Electronic Resource
    Das erste helicale Naphthalinophan - Synthese, Enantiomerentrennung, Circulardichroismus und Racemisierungsbarriere (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1113-1117 
    Details
    ISSN: 0009-2940
    Keywords: 1-Oxa-[2.2](2,7)naphthalenophane ; Helical molecules ; Ring strain ; Circular dichroism ; Thiaphanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The First Helical Naphthalenophane - Synthesis, Separation off Enantiomers, Circular Dichroism, and Barrier of RacemisationPreparation and properties of the title compound (2; 1-Oxa-[2.2](2,7)naphthalenophane) are described. The enantiomers of 2 were separated or enriched by HPLC on cellulose-tris(3,5-dimethylphenyl)carbamate. Circular dichroism and kinetics of racemisation were elucidated. The energy barrier of ring inversion for the intermediate thia[3.2]phane 9 was determined. Spectroscopic and chiroptical properties are compared to the metacyclophane 1a and the [2.1]naphthalenophane 3.
    Notes: Erstmalige Darstellung und Eigenschaften der chiralen Titelverbindung (2; 1-Oxa[2.2](2,7)naphthalinophan) werden beschrieben. Deren Enantiomere wurden durch HPLC an Cellulose-tris-(3,5-dimethyphenyl)carbamat getrennt bzw. angereichert. Circulardichroismus und Racemisierungskinetik von 2 wurden ermittelt. Außerdem wurde die Energiebarriere für Ringinversion des intermediären Thia[3.2]phans 9 bestimmt. Spektroskopische und chiroptische Eigenschaften von 2 werden anhand des Metacyclophans 1a und des [2.1]Naphthalinophans 3 erörtert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220617
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  • 4
    Electronic Resource
    Electronic Resource
    Intra- und extraannular funktionalisierte helical-chirale [2.2]Metacyclophane: Synthese, Circulardichroismus und Struktur-Chiroptik-Beziehungen (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1859-1868 
    Details
    ISSN: 0009-2940
    Keywords: Circular dichroism ; [2.2]Metacyclophanes ; Helical molecules ; Absolute configuration ; Structure-chiroptic relationships ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intra- und Extraannularly Functionalized Chiral [2.2]Metacyclophanes: Synthesis, Circular Dichroism, and Structure - Chiroptic RelationshipsA simple one-step cyclization reaction for the synthesis of the title compounds 1-5 is presented; separation (enrichment) of enantiomers is achieved by HPLC mainly on (+)-PTrMA. The kinetics of interconversion (racemization) of the new dihetera[2.2]metacyclophanes are determined: No racemization of the internally substituted phanes is found on heating until decomposition, whereas the extraannularly substituted compounds exhibit barriers of interconversion of about 130 kJ/mol, similar to that of the unfunctionalized skeleton 1a. For the pyridinophane 2 the barrier (110 kJ/mol) is lower corresponding to the decreased spatial requirement of the nitrogen lone pair compared to a C-H bond. The circular dichroism curves of the intraannularly functionalized phanes are compared with those of the extraannularly functionalized reference compounds: A bathochromic shift of the Cotton effect at short wavelengths is found, which is increasing with the bulkiness of the internal functional group.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230918
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  • 5
    Electronic Resource
    Electronic Resource
    Nitro- und Allyloxy-substituierte helicale [2.2]Metacyclophane: Synthese, Circulardichroismus und Röntgen-Kristallstrukturanalysen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1585-1590 
    Details
    ISSN: 0009-2940
    Keywords: Charge transfer ; Circular dichroism ; Helical molecules ; [2.2]Metacyclophanes ; Structure-chiroptic relationships ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nitro- and Allyloxy-Substituted Helical [2.2]Metacyclophanes: Synthesis, Circular Dichroism and Crystal StructuresThe preparations of the title compound 3a, intraannularly nitro-functionalized, of the extraannularly substituted reference compound 3b, and of the sulfone 4 are described. Enantiomeric resolution of these helical phanes was accomplished on (+)-PTrMA and cellulose tris(3,5-dimethylphenyl)carbamate by HPLC. Racemization of the enantiomers of 3b is faster than that of the previously reported extraannularly substituted phanes. The crystal structure of 3a as well as that of the allyl ether 3d show severe distortions of the benzene rings; the CD spectrum of 3a is pointing at an intramolecular charge-transfer complex, an effect that cannot be evaluated from the CD spectrum of 3b.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240719
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  • 6
    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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  • 7
    Electronic Resource
    Electronic Resource
    Non-Ionic Template Synthesis of Amide-Linked Rotaxanes: Olefinic and Aliphatic Axle Building Blocks (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 2269-2273 
    Details
    ISSN: 0947-3440
    Keywords: Association constant ; Mechanical bonding ; Molecular recognition ; Template synthesis ; Supramolecular chemistry ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first synthesis of amide-linked rotaxanes with non-arene axle building blocks is reported. The threading synthesis of rotaxane 8 with olefinic fumaryl chloride proves that arene moieties are not necessary for non-ionic template syntheses. Mass spectroscopic evidence of a rotaxane bearing an aliphatic axle, derived from succinic acid, revealed that hydrogen bonding, rather than π,π interactions, is the predominant template binding force. 1H-NMR titration studies on the threading synthesis of these mechanically bonded molecules were carried out. The association constants measured suggest that the incorporation of the corresponding monoamide monochloride (cf. 7), rather than the incorporation of the diacid dichloride (cf. 5), plays the key role in these rotaxane syntheses. The X-ray structural analysis of a semi axle (14) reveals hydrogen bonding patterns characteristic of diamides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719971114
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  • 8
    Electronic Resource
    Electronic Resource
    Nanometre-scale molecular ribbonsDedicated to Professor Heinz A. Staab on the occasion of his 70th birthday (1996)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 2 (1996), S. 832-837 
    Details
    ISSN: 0947-6539
    Keywords: cyclophanes ; macrocyclisations ; molecular ribbons ; nanostructures ; repetitive syntheses ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The longest molecular ribbons known to date (3-10), composed of a series of [3.3]metacyclophane units, have been synthesised by means of a repetitive synthetic strategy. These multiple ring systems with up to nine bridged benzene rings in a row are the longest structurally perfect cyclophane sequences known to date. The synthetic strategy comprises three steps: ester reduction to a tetrakis(hydroxymethyl) compound, derivatisation to the corresponding tetrakis(bromomethyl) derivative, and double cyclisation with the new key building block 14, which was especially developed for this sequence. Single-crystal X-ray analyses (3 a-7 a) and 1H NMR spectroscopy (3-10) show that, regardless of their length, these molecules adopt zigzag folded all-syn conformations. π-Stacks of nanometre dimensions are thus formed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.1460020714
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  • 9
    Electronic Resource
    Electronic Resource
    Concave Hydrocarbons (1996)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 2 (1996), S. 1585-1595 
    Details
    ISSN: 0947-6539
    Keywords: concave hydrocarbons ; cyclophanes ; host/guest chemistry ; ion-selective electrodes ; prismands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Concave hydrocarbons, such as 1 (C36H36), 4 (C60H60), 5 (C54H48), and 6 (C60H52), represent three-dimensionally clamped analogues of π-prismands. They encapsulate small metal ions and accomplish metal-ion extraction from aqueous solution. Their remarkable selectivity allows applications such as incorporation in ion-selective electrodes. The synthetic route is based on well-established cyclophane methodology and, thus, offers a general approach to a whole family of concave hydrocarbons.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19960021218
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  • 10
    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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