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  • General Chemistry  (34)
  • Organic Chemistry  (7)
  • Cyclic voltammetry  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Chromophore-Appended C60 and C70 Fullerenes: Anthracene and Pyrene Derivatives - Syntheses, Cyclic Voltammetry, and Spectra (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1549-1557 
    Details
    ISSN: 1434-193X
    Keywords: Functionalized fullerenes ; Cyclic voltammetry, spectroelectrochemistry ; Ions and radical ions ; Absorption and emission spectra ; Intramolecular energy transfer ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: C60 and C70 adducts containing spacer-linked phenyl (BK1), 9-anthracenyl (BK2), 4-(9-anthracenyl)phenyl (BK3), and 1-pyrenyl groups (BE1 and FE1) have been studied. Two different synthetic pathways were employed based on the [4+2] cycloaddition of fullerenes with 2-trimethylsiloxy-1,3-butadienes (TB). Spectroscopic data for the new compounds are given. Electrochemical and optoelectrochemical studies were undertaken by using cyclic voltammetry and spectroelectrochemical methods. The fluorescence emission spectra of BK2, BK3, BE1, and FE1 are reported. Intramolecular energy transfer from the excited fluorophore to the fullerene subunit is shown to occur.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Electron-Transfer Chemistry and Redox-Switching of Stilbene-Like Heteroaromatic Compounds  -  Syntheses, Optoelectrochemical and ESR/ENDOR StudiesDedicated to Prof. M. Hanack on the occasion of his 65th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 2069-2077 
    Details
    ISSN: 0947-3440
    Keywords: Stilbenes ; Push-pull substitution ; Electron transfer ; (Z)/(E) Isomerisation ; Radical ions ; Cyclic voltammetry ; Spectroelectrochemistry ; ESR / ENDOR ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Redox-active compounds, in which the electron donor and the acceptor subunits are covalently linked by a vinylene spacer group were synthesised and their properties were investigated by cyclovoltammetry, spectroelectrochemistry, and ESR/ENDOR spectroscopy.  -  10-Methylphenothiazinyl, 10-methylphenoxazinyl, and phenoxathiinyl were used as electron-donating groups whereas 9,10-anthraquinon-2-yl and phenyl groups were employed as acceptors. The synthesis of the push-pull-substituted stilbenes 1a, 1b, 1c, 2a, 2b and 2c was achieved by Wittig coupling of the heterocyclic aldehydes with the anthraquinoyl or phenyl phosphonium salts. The diastereoisomers were separated either by chromatography or by crystallization.  -  The redox potentials of the (Z) and (E) isomers differ only slightly. Spectroelectrochemical measurements indicate that the radical cations of the phenothiazine and phenoxazine derivatives undergo rearrangement from the (Z) to the (E) isomers. On the other hand, electron attachment leads to configurationally stable radical anions. This behaviour is rationalised in terms of the electron distribution reflected by the hyperfine data established by ESR/ENDOR spectroscopy.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961218
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  • 3
    Electronic Resource
    Electronic Resource
    Topologic Equivalents of Coronands, Cryptands and Their Inclusion Complexes: Synthesis, Structure and Properties of {2}-Metallacryptands and {2}-MetallacryptatesChelate complexes, part 9; for part 8 see ref. [7].Dedicated to Professor Paul von Ragué Schleyer on the occasion of his 68th birthday (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 2058-2062 
    Details
    ISSN: 0947-6539
    Keywords: iron ; metallacryptands ; metalla-cryptates ; self-assembly ; structure elucidation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and structural characterisation of two dinuclear iron(III) complexes are reported. The compounds of general structure [Fe2L13] [8; L1 = dianion of 2,2′-dicyano-2,2′-isophthaloyldi(isopropyldicarboxylate)] and [K ⊂ Fe2L23]+ (PF6)- [10; L2 = dianion of 1,1′-(2,6-pyridylene)bis-1,3-(4-dimethyl)-pentanedione] are formed by the deprotonation of ligands 7 and 9 with triethylamine and potassium hydride respectively, followed by addition of iron(III) chloride and work up with water or aqueous potassium hexafluorophosphate. X-ray crystallographic studies reveal that 8 is a racemic mixture composed of triple helicates with (Δ,Δ)-fac and (Δ,Δ)-fac configuration at the two iron bridgeheads. In contrast to racemic 8, the two iron centres in the meso-10 [(Δ,Δ)-fac] have opposite configuration. Investigations of the redox-active iron centres in {2}-metallacryptand 8 and {2}-metallacryptate 10 by cyclic voltammetry show slightly different behaviour. The peaks for the two consecutive reductions of the two iron centres of 8 can hardly be resolved, whereas 10 shows two well-separated peaks. Mössbauer measurements were performed on 8 and 10 between 4.2 and 300 K, with and without a field applied perpendicular or parallel to the γ-beam. All zero-field and 20 mT spectra exhibit a broad and unresolved absorption pattern. Application of 5.3 T at 4.2 K results in well-resolved magnetic hyperfine patterns which are practically the same for 8 and 10.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970031222
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  • 4
    Electronic Resource
    Electronic Resource
    Multi-mode switching based on dihydroazulene/vinylheptafulvene photochromism: Synergism of photochromism and redox switching in heteroaryl-functionalized systemsFor the preceeding publication. see ref. [1]. (1996)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 2 (1996), S. 1150-1158 
    Details
    ISSN: 0947-6539
    Keywords: electrochromes ; cyclic voltammetry ; heterocycles ; optical memory ; photochromes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses of the dihydroazulenes (DHAs) DHA-a-DHA-f containing covalently linked heteroaromatic subunits derived from dibenzodioxin, thianthrene, phenoxathiine, N-methylphenothiazine, N-methylphenoxazine, and N,N′-dimethylphenazine groups are described, and their spectroscopic and analytical data are reported. The dihydroazulene/vinylheptafulvene (DHA/VHF) photochromism (photochemical forward and thermal back reaction) depends with high sensitivity on the electronic properties of the functional groups. Whereas the dimethylphenazine derivative DHA-f is photochemically inactive towards rearrangement, all other DHAs (DHA-a-DHA-e) were found to isomerize to the corresponding vinylheptafulvene forms under irradiation. Cyclic voltammetry revealed that the DHA and the VHP forms have significantly different oxidation and reduction waves. The products of the-oxidative one-electron transfer are characterized by UV/Vis/NIR spectroelectrochemistry. Those DHAs having weaker donor substituents (DHA-a-DHA-c) undergo oxidative dimerization whereas DHAs with stronger donating heterocyclic subunits (DHA-d-DHA-f) form stable radical cations.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.1460020916
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  • 5
    Electronic Resource
    Electronic Resource
    Functional dyes for molecular switchingPreceding communication: Ref.. Dihydroazulene/vinylheptafulvene photochromism: Effect of π-arylenes on the switching behaviorDedicated to Prof. F. Effenberger on the occasion of his 65th birthday. (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 1637-1641 
    Details
    ISSN: 0947-3440
    Keywords: Thermal and photochemical electrocyclization reactions ; Photochromism ; Molecular switching ; Luminescent properties ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reversible interconversion of dihydroazulene (DHA) and vinylheptafulvene (VHF) can be utilized to switch a number of physical properties. This communication reports on a fluorescent switch. By a multistep sequence involving an [8 + 2] cycloaddition route 9-anthracenyl-1,4-phenylene was covalently attached to C-2 of the DHA chromophore affording DHA-1 which undergoes complete and clean photochemical ring opening to vinylheptafulvene VHF-1. The latter is thermally reverted to DHA-1. The kinetics and the energetics of the thermal back reaction are discussed. On/off switching of luminescence was investigated: DHA-1 displays fluorescence whereas VHF-1 is nonfluorescent at ambient temperature.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1995199509227
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  • 6
    Electronic Resource
    Electronic Resource
    Stabile 2,4,6-Cycloheptatrien-1-ylmethyl-Kationen (1971)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 83 (1971), S. 289-290 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19710830808
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  • 7
    Electronic Resource
    Electronic Resource
    Stereochemiekontrolle durch sekundäre “through space”-Wechselwirkung: exo/endo-Stabilität 7-acceptorsubstituierter 2,4-Norcaradiene (1974)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 86 (1974), S. 54-54 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19740860116
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  • 8
    Electronic Resource
    Electronic Resource
    Konstitutions- und Konfigurationsstabilität eines Carbamoyltetracarbonyleisen-AnionkomplexesDiese Arbeit wurde von der Deutschen Forschungsgemeinschaft und dem Fonds der Chemischen Industrie unterstützt. (1975)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 87 (1975), S. 489-490 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19750871310
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  • 9
    Electronic Resource
    Electronic Resource
    Ein erstes Beispiel eines porphyrinoiden Fulvalens: Synthese, Struktur, ESR- und elektrochemische UntersuchungenProf. Dr. Fabian Gerson in Anerkennung seiner Beiträge zum Verständnis von π-Systemen gewidmet (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 2456-2476 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A First Example of a Porphyrinoid Fulvalene: Synthesis, Structure, ESR and Electrochemical InvestigationsThe macrocyclic tetraepoxy-1H-[21]annulen-1-one 4 can by synthesized by the cyclizing Wittig reaction of 5,5′-carbonylbis[furan-2-carboxaldehyde] (11) and the bisphosphonium salt 12, obtained from 2,2′-bifuran-5,5′-dicarboxaldehyde (13). According to an X-ray structure analysis, the annulenone 4 is not planar in the crystal; the 1H-NMR spectra of 4 reveal an averaged planarity with respect to the NMR timescale. The McMurry reaction of 4 yields fulvalene 3 in 43% yield as the most expanded fulvalene hithertoo known. The X-ray structure analyses of 3 surprising establishes a ‘syn’-orientation of the two rings with respect to the central C=C bond, thus forming a basket-like molecule. The 1H-NMR spectrum confirms the averaged planarity of both macrocycles in 3. CV and spectroelectrochemical measurements of 3 suggest a reversible two-electron reduction producing dianion 15 with two aromatic, anionic 5a,15a-didehydro-10H-21,22,23,24-tetraoxa-5a,15a-dihomocorrole (= tetraoxa[22]porphyrin(2.1.2.0)) ring systems containing 22π electrons each. The formation of 15 can also be achieved chemically by reaction of 3 with metallic potassium. The dication 16 of 3 may be antiaromatic, but the exact electronic structure is dubious. ESR and ENDOR investigations on the radical cation and the radical anion of 3 indicate that the free electron is delocalized in the entire molecule.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800814
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  • 10
    Electronic Resource
    Electronic Resource
    Elektronentransferchemie chinoider Verbindungen: Chemische, elektrochemische und UV/VIS-spektroelektrochemische Untersuchungen von Acenazulendionen (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 727-735 
    Details
    ISSN: 0009-2940
    Keywords: Quinones ; Electron exchange ; Radical ions ; Cyclic voltammetry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Electron-Transfer Behaviour of Quinoid Compounds: Acenazulenediones - A Study by Chemical and Electrochemical Methods and by UV/VIS SpectroelectrochemistryIn contrast to arene-condensed benzoquinones, polycyclic 1,4-quinones (Q) containing azulenoid partial structurs dimerize on reduction to their radical anions. These investigations were undertaken with naphth[2,3-a]azulene-5,12-dione (1), azuleno[1,2-b]anthracene-6,13-dione (8), benzazulenediones 10, and with benz[a]anthracene-7,12-dione (9). Evidence which originally came from cyclovoltammetry is now confirmed by spectroscopic data (UV/VIS spectroelectrochemistry) and by chemical reduction with sodium metal. The equilibrium 2 Q·- ⇌ (Q-Q)2- depends strongly on structural details. In case of extended arene condensation it is shifted to the dimeric. The structure and the electron transfer behaviour of the dimeric dianions (Q-Q)2- are determined. The radical anions (Q)·- are characterized by their UV/VIS spectra obtained from UV/VIS spectroelectrochemistry. A qualitative evaluation of the strength of the central bond in the radical anions (Q-Q)·- as well as in the dianions (Q-Q)2- and the radical trianions (Q-Q)3·- is given. Some chemical and physical properties of the radical cation 1·+ are reported.
    Notes: Polycyclische Chinone (Q) mit azulenoiden Teilstrukturen dimerisieren bei der Reduktion zu den Radikalanionen. Die konstitutionsisomeren arenkondensierten Verbindungen zeigen dieses Verhalten nicht. Dies wird am Beispiel von Naphth[2,3-a]azulen-5,12-dion (1), Azuleno[1,2-b]anthracen-6,13-dion (8), Benzazulendionen 10 und Benz[a]anthracen-7,12-dion (9) gezeigt. Erste Hinweise für die Ursache dieses Verhaltens stammen aus Untersuchungen mit der Cyclovoltammetrie. Eine Bestätigung dieser Ergebnisse erfolgt jetzt durch spektroskopische Daten (UV/VIS-Spektroelektrochemie) und durch die chemische Reduktion mit Natrium. Die Lage des Gleichgewichts 2 Q·- ⇌ (Q-Q)2- ist strukturabhängig. Die Strukturen der dimeren Dianionen (Q-Q)2- und der Radikalanionen (Q)-) werden durch Elektronenspektroskopie und teilweise durch 1H-NMR charakterisiert und zugeordnet. Die Stärke der zentralen Bindung der Radikalanionen (Q-Q)·-, Dianionen (Q-Q)2- und Radikaltrianionen (Q-Q)3·- wird qualitativ abgeschätzt. Über einige chemische und physikalische Eigenschaften des Radikalkations 1·+ wird außerdem berichtet.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220421
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