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  • Intramolecular electron transfer  (3)
  • Absorption and emission spectra of porphyrin-quinone cyclophanes  (2)
  • Isoalloxazinophanes  (2)
  • 1
    Electronic Resource
    Electronic Resource
    [3.3]Isoalloxazinophanes and Arene-Bridged Bis(isoalloxazines): Syntheses, Characterizations and Properties Related to Intramolecular Interactions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1653-1665 
    Details
    ISSN: 0009-2940
    Keywords: Flavin-flavin interactions ; Isoalloxazinophanes ; Bis(isoalloxazinyl)arenes ; Bis(isoalloxazines), absorption spectra and cyclovoltammetry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to study the orientation and distance dependence of π … π interactions between flavins in various redox states, two approaches to bis(isoalloxazine) model compounds are presented: The [3.3]isoalloxazinophanes 2 and 4 and the rigid single-bridged 1,8-naphthalene- and 1,8-anthracene-linked bis(isoalloxazine) systems 6, 8 and 26 were synthesized, characterized, and studied by spectroscopic methods and cyclic voltammetry. The experimental data are discussed in comparison with “monomeric” isoalloxazines and flexible single-chain trimethylene-linked bis(isoalloxazine) reference compounds. X-Ray structure analyses are reported for the 1,8-bis(isoalloxazinyl)-9,10-dihydroanthracene 26 and for 22 as an example of 1,8-disubstituted naphthalenes with strongly polar substituents comparable to 6.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270917
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Photoinduced electron transfer in porphyrin-quinone cyclophanes, 7. Porphyrin-quinone cyclophanes with gradually varied acceptor strength: Physical properties related to electron transfer (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2303-2310 
    Details
    ISSN: 0009-2940
    Keywords: Porphyrin-quinone cyclophanes ; Photoinduced electron transfer in porphyrin-quinone cyclophanes ; Absorption and emission spectra of porphyrin-quinone cyclophanes ; Redox potentials and electron transfer in intramolecular porphyrin-quinone systems ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Absorption and emission spectra of the doubly quinone-bridged porphyrin cyclophanes 1-4 with gradually varied acceptor strength as well as of the single-bridged analogues 5-9 and 10-13 are reported. Reduction and oxidation potentials of these intramolecular porphyrin-quinone systems have been determined. Based on these data, fluorescence quenching as well as time-resolved fluorescence lifetime measurements are discussed in terms of photoinduced electron transfer to the charge-separated zwitterionic state.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251018
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Syntheses and Properties of New Quinone-Bridged Diphenyl- and Tetraphenylporphyrins (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 223-229 
    Details
    ISSN: 0009-2940
    Keywords: Porphyrin-quinone cyclophanes ; Photoinduced electron transfer ; Absorption and emission spectra of porphyrin-quinone cyclophanes ; Photosynthesis models ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses and spectroscopic properties of the porphyrin-quinone cyclophanes 1, 2 and 3 of which structural and/or conformational studies have recently reported[1] are described. Physical properties related to photoinduced electron-transfer reactions like redox potentials, absorption and emission spectra were determined for these compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270132
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  • 4
    Electronic Resource
    Electronic Resource
    Intramolecular Electron Transfer between Terminal 1,4-Dimethoxybenzene Units in Radical Cations with a [2.2](1,4)Naphthalenophane, [2.2](1,4)Anthracenophane, and Pentacene Skeleton (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1161-1170 
    Details
    ISSN: 1434-193X
    Keywords: [2.2](1,4)Naphthalenophanes ; [2.2](1,4)Anthracenophane ; Pentacene ; Cyclic voltammetry ; Radical cations ; ESR/ENDOR spectroscopy ; Intramolecular electron transfer ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various radical cations, in which two terminal 1,4-dimethoxybenzene units are anellated to [2.2]paracyclophane (2b•+, 3b•+), [2.2](1,4)naphthalenophane (4d•+), and anthracene bridges (5•+), have been studied by ESR and ENDOR spectroscopy. In the syn- and anti-naphthalenophane radical cations 2b•+ and 3b•+ the delocalization of the unpaired electron over both π-moieties and the distinct difference between the first and second oxidation potentials, ΔE = E20 - E10, are evidence for a substantial intramolecular electronic interaction between the two electrophores. Extension of the bridge in 4d•+ and 5 by benzo anellation results in a localized radical cation. Strong intramolecular electronic interaction between the two electrophores is found in the 1,4,8,11-tetramethoxy-pentacene radical cation (5•+). The syntheses of 4d are described.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    π…π interactions of flavins, 5. Syntheses, structures and physical properties of flavin systems with covalent bonding to π donors and π acceptors (quinones) (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 1827-1836 
    Details
    ISSN: 0947-3440
    Keywords: Isoalloxazinophanes ; Flavins ; π Donors ; π Acceptors ; Quinones ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To study π…π interactions of flavins of different redox states with π-electron donors and acceptors, the syntheses of compounds in which such π systems are linked to flavins by using the „cyclophane concept“ were attempted and partially achieved. The syntheses of the metacyclo-isoalloxazinophanes 1 and 2 are reported as well as the X-ray structure analysis of 2. The conversion of 1 or 2 to the benzoquinono-isoalloxazinophanes 3 or 4, respectively, was not achieved, obviously due to the specific sterical shielding of the methoxy groups in the isoalloxazinophanes. Benzoquinone-isoalloxazine systems in which the two components are linked by only one triethylene chain were obtained. Spectroscopic and electrochemical properties related to intramolecular interactions are reported.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1995199510256
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  • 6
    Electronic Resource
    Electronic Resource
    [2.2]Paracyclophane-4,7,12,15-tetrone, [2.2](1,4)Naphthalenophane-4,7,14,17-tetrone, and 1,4,8,11-Pentacenetetrone Radical Anions - A Comparative ESR Study (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 221-227 
    Details
    ISSN: 1434-193X
    Keywords: 1,4-Benzoquinones ; [2.2]Paracyclophanes ; 1,4,8,11-Pentacenetetrones ; Cyclic voltammetry ; Radical anions ; ESR/ENDOR spectroscopy ; Intramolecular electron transfer ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three types of tetrone radical anions in which two 1,4-benzoquinone units are connected by ethano (1·-, 2·-), [2.2]paracyclophane (3·-, 4·-), and anthracene bridges (5·-, 6·-) have been studied by ESR and ENDOR spectroscopy. The displacement of the unpaired electron over the two π moieties in the [2.2]cyclophane radical anions 1·--4·- and the marked difference between the first and second reduction potentials, ΔE = |E20 - E10| ≥ 0.20 V, are evidence for a substantial intramolecular electronic interaction between the two electrophores. Similar ΔE data for the syn- (3) and anti-naphthalenophanes (4) indicate that most of the intramolecular electronic interaction takes place through the [2.2]paracyclophane bridge. When ion pairing is inhibited by complexation of the cation, the unpaired electron in 5·- and 6·- is also delocalized over the whole pentacenetetrone system at temperatures as low as 160 K.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 7
    Electronic Resource
    Electronic Resource
    Intramolecular Electron Transfer between 2,5-Dimethoxy-1,4-phenylene Units in [n.n]Paracyclophane Radical Cations (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 139-148 
    Details
    ISSN: 1434-193X
    Keywords: Paracyclophanes ; Cyclic voltammetry ; Radical cations ; ESR/ENDOR spectroscopy ; Intramolecular electron transfer ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A range of [n.n]paracyclophane radical cations (4·+-12·+), in which two 2,5-dimethoxy-1,4-phenylene units are connected by alkano bridges of varying length, have been studied by ESR and ENDOR spectroscopy. In the [2.2]- and [3.3]paracyclophane radical cations 4·+-6·+, 10·+ and 11·+ the delocalization of the unpaired electron over both π-moieties and the distinct difference between the first and second oxidation potentials, ΔE = E20 - E10, are evidence for a strong intramolecular electronic interaction between the two electrophores. The [5.5] and [7.7] species (8·+ and 9·+) are localized radical cations at low temperature (ca. 220 K). At room temperature, the higher molecular flexibility leads to a significant increase in the number of internal collisions between the electrophores, resulting in a fast (ESR time scale) intramolecular electron transfer. The intermediate [4.4]paracyclophane radical cations 7·+ and 12·+ are apparently also localized radical cations. The close interplanar distance between the two π-moieties, however, facilitates their mutual contacts. In 7·+, the intramolecular electron transfer becomes fast on the ESR time scale at room temperature; in 12·+ the transfer is fast over the temperature range 200-300 K.
    Type of Medium: Electronic Resource
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