Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Modellgestützte Regelung von WärmeaustauschernVortrag von H. PREISIG auf der GVC-Jahrestagung, 28./30. Sept. 1994 in Aachen. (1995)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 67 (1995), S. 1472-1476 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330671110
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    Distance Dependence of Photoinduced Electron Transfer: Syntheses and Properties of Anthracene-Spacered Porphyrin-Quinone Cyclophanes (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 631-642 
    Details
    ISSN: 1434-193X
    Keywords: Electron transfer, distance dependence of ; Anthracene-spacered porphyrin-quinone cyclophanes ; Syntheses ; Characterizations ; Structures ; Physical properties ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In our previous work on benzene- and naphthalene-spacered porphyrin-quinone cyclophanes[1][2], the dependence of electron-transfer rates on reduction potentials of the acceptors and oxidation potentials of the porphyrins was studied. The present paper, dealing with the distance dependence of electron transfer, reports on the synthesis of anthracene-spacered analogues and on the electron-transfer rates, which are found to be drastically reduced.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 4
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Distance Dependence of Photoinduced Electron-Transfer: Syntheses and Properties of Biphenylene-Spacered Porphyrin-Quinone Cyclophanes (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 2149-2160 
    Details
    ISSN: 1434-193X
    Keywords: Porphyrin-quinone systems ; Biphenylene-spacered cyclophanes ; Syntheses, structures, spectroscopic properties ; Electron-transfer rates, distance dependence of ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In continuation of previous syntheses of benzene-, naphthalene-, and anthracene-spacered porphyrin-quinone cyclophanes 1, 2, and 4, biphenylene-spacered porphyrin-quinone cyclophanes of structure 3 as the “missing link” between 2 and 4 were prepared in multistep syntheses. These donor-acceptor systems are of interest since, with regard to electron-transfer rates, they complete the series of 1, 2, and 4. As expected the electron-transfer of 3 proceeds between that of 2 and 4 in an especially steep region of distance dependences of electron-transfer rates.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Porphyrin-Cyclophanes with 7,7,8,8-Tetracyanoquinodimethane as an Especially Strong Electron-Acceptor: Syntheses, Properties, Electron-Transfer Interactions (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 2703-2711 
    Details
    ISSN: 1434-193X
    Keywords: Porphyrin-acceptor cyclophanes ; 7,7,8,8-Tetracyanoquinodimethane (TCNQ)-bridged porphyrins ; Electron-transfer-related properties ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Previous work on intramolecular electron-transfer compounds of the quinone-porphyrin cyclophane type with gradually increasing electron-acceptor strength was now extended to acceptor-porphyrin cyclophanes with 7,7,8,8-tetracyanoquinodimethane (TCNQ) as an especially strong electron-acceptor. The vertically stacked TCNQ-porphyrin cyclophane 1 was prepared in a multi-step synthesis. Physical properties related to structure and electron-transfer processes of 1 are reported. To determine the distance dependence of the interaction between the electron-acceptor TCNQ and the porphyrin, first results on the synthesis of the corresponding naphthalene-spacered TCNQ-porphyrin cyclophane 15 are presented.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 7
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 8
    Electronic Resource
    Electronic Resource
    Pyromellitic Diimide-Porphyrin Cyclophanes: Syntheses, Transannular Interactions, and Structure Analysis (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1459-1470 
    Details
    ISSN: 1434-193X
    Keywords: Cyclophanes ; Donor-acceptor systems ; Syntheses ; Conformation analysis ; X-ray structure analysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The acceptor-porphyrin cyclophanes 2 and 4 with pyromellitic diimide (1) as strong electron-acceptor, and the corresponding porphyrin zinc complexes 3 and 5 were prepared by a route which differs considerably from that in the syntheses of previously prepared electron-acceptor porphyrin cyclophanes. The conformations of these electron-acceptor-porphyrin cyclophanes are discussed based on 1H-NMR and the X-ray structural analysis of 2. According to the results obtained, the plane of 1 and that of the porphyrin unit (at least in the crystalline state) are neither close nor parallel to each other. An unusual dihedral orientation of the donor and acceptor planes was detected for 2.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 9
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Photoinduced Electron-Transfer in Porphyrin-quinone Cyclophanes, 15.Part 14: Ref. Distance Dependence of Photoinduced Electron-Transfer: Syntheses and Structures of Naphthalene-Spacered Porphyrin-Quinone Cyclophanes (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 2321-2336 
    Details
    ISSN: 0947-3440
    Keywords: Photoinduced electron-transfer, distance dependence ; Naphthalene-spacered porphyrin-quinone cyclophanes ; Synthesis, conformations, structural analysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses, conformational and structural analyses of porphyrin-quinone cyclophanes 2 with naphthalene-spacers are presented and the findings are compared with data for previously investigated analogous benzene-spacered compounds 1. In combination with data for the biphenylene- and anthracene-spacered porphyrin-quinone cyclophanes 3 and 4, to be published in following papers, the results reported herein allow some appraisal to be made of the distance dependences of photoinduced electron-transfer from porphyrin to quinone units.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719971121
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...