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  • 1
    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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  • 2
    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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  • 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
    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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