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  • 1
    Electronic Resource
    Electronic Resource
    [2.2](2,6)- and [2.2](2,5)Pyrazinophanes: Synthesis and Molecular Structure (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 523-533 
    Details
    ISSN: 0009-2940
    Keywords: Hofman 1,6-elimination / Pyrazine derivatives / [2.2]Pyrazinophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compounds 1-3 and their methyl derivatives 4-7 were synthesized 2,11-dithia[3.3]pyrazinophanes 24-26 or by Hofmann 1,6-elimination of the appropriate [(5-methyl-2-pyrazinyl)methyl]trimethylammonium hydroxides followed by dimerization of the generated 2,5-dihydro-2,5-dimethylenepyrazines. α-Chlorination of the methylpyrazines 8-10 with N-chlorosuccinimide gave the required precursors 11, 12, 14, 17 and 18. The results of the X-ray structure determinations for 1-4 and 7 which indicate an unequivocal isomer assignment are discussed with regard to steric strain in these molecules. The electronic spectra of the pyrazinophanes 7-7 are reported and compared with those of the parent methylpyrazines.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230319
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  • 2
    Electronic Resource
    Electronic Resource
    Oligooxa[3n.3]paracyclophane Quinhydrones  -  Cation-Induced Charge-Transfer Absorptions and Structures of the Metal Complexes (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1993-2008 
    Details
    ISSN: 0009-2940
    Keywords: Electron donor-acceptor cyclophanes ; Charge-transfer compounds ; Crown ethers ; Oligooxaparacyclophane metal complexes, charge-transfer absorption of, crystal structures of ; Cyclophanes, electron donor-acceptor ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The intramolecular oligooxa[3n.3]paracyclophane quinhy-drones 2-5 (with n = 3 to 6) were synthesized and their interactions with alkali and alkaline earth metal and mercury(II) ions were studied by electron absorption and NMR spectroscopy. Remarkable enhancements of the CT absorptions were observed by complexation with metal ions of the pentaoxa[15.3]paracyclophane quinhydrone 4 and the hexaoxa[18.3]paracyclophane quinhydrone 5 to the corresponding complexes 6a-e and 7, respectively. The various donor-acceptor orientations and the crown ether-like complexation in the calcium complex 6d, the mercury complex 6e and the barium complex 7 were determined by X-ray analysis. Moreover, the X-ray structures of the tetramethoxy-2,5,8-trioxa[9.3]paracyclophane 8a, a precursor of the quinhydrone 2, and of the pentaoxa[15.3](2,5)-p-benzoquinonophane 20, the product of oxidative demethylation of the quinhydrone 4, are given. For comparison with the cyclic quinhydrones acyclic analogs are also described.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271024
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  • 3
    Electronic Resource
    Electronic Resource
    Photoinduced Electron Transfer in Porphyrin-Quinone Cyclophanes, 8 Conformational Mobility and Crystal Structures of Porphyrin-Quinone Cyclophanes (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 811-821 
    Details
    ISSN: 0009-2940
    Keywords: Porphyrin-quinone cyclophanes ; Photoinduced electron transfer ; Porphyrin cyclophanes, conformational mobility of, crystal structures of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to correlate photoinduced electron-transfer in porphyrin-quinone cyclophanes to specific molecular conformations, the internal mobility of single-and double-bridged porphyrin-quinone cyclophanes was studied by low-temperature 1H-NMR measurements. The dynamic processes observed are discussed in terms of N-H/N tautomerisation, of the rotation of the rings in the bridges, and of a specific “swinging bridge” process back and forth between two equivalent unsymmetrical conformations with a tilted orientation of the porphyrin and quinone ring planes. For comparison with the conformational situation in solution the results of X-ray structure analyses of 3(X=OMe) and 6, as representative examples of single-bridged quinone-porphyrin cyclophanes, and of the corresponding tetramethoxybenzene-bridged octamethylporphyrin cyclophane 4(X=OMe) are reported and discussed. In contrast to the previously solved crystal structure of the quinone-porphyrin-quinone cyclophane 1(X=H), all three X-ray structure analyses of the single-bridged porphyrin cyclophanes proved the existence of unsymmetrical, tilted-plane structures similar to those discussed as the stable conformations in the “swinging bridge” process.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260336
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  • 4
    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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  • 5
    Electronic Resource
    Electronic Resource
    Pyridinio-isoalloxazinophanes as Model Systems for Active-Site Complexes in Flavoenzymes: Syntheses, X-Ray Structure Analyses and Spectroscopic Properties (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1667-1680 
    Details
    ISSN: 0009-2940
    Keywords: Isoalloxazinocyclophanes ; Pyridinio-isoalloxazinophanes ; Nicotinic ester and nicotinic acid isoalloxazinophanes, intramolecular interactions of, X-ray structure analyses of ; Flavin-nicotinamide models ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As model systems for active site complexes in flavoenzymes, flavin and nicotinamide analogues were linked together in cyclophane skeletons of specific sterical structures. Elaborating this concept, we prepared [4]metacyclo[3](10,6)isoalloxazinophane (3), [4](3,1)pyridino[3](10,6)isoalloxazinophane (4), as well as the 16-methoxycarbonyl and the 16-carboxylato derivatives (2 and 34, resp.), of 4 by multistep syntheses. For the isoalloxazinophanes 2, 3, 4, and 34 X-ray structure analyses were performed and are discussed with regard to intramolecular interactions. Preliminary UV/Vis-spectroscopic results related to π…π interactions in these isoalloxazinophanes are reported.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270918
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  • 6
    Electronic Resource
    Electronic Resource
    Photoinduced electron transfer in porphyrin-quinone cyclophanes, 6. Porphyrin-quinone cyclophanes with gradually varied acceptor strength: Syntheses and characterizations (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2285-2301 
    Details
    ISSN: 0009-2940
    Keywords: Porphyrin-quinone cyclophanes ; Photoinduced electron transfer ; Porphyrin cyclophane syntheses ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For studying intramolecular electron-transfer reactions, three groups of double- and single-bridged porphyrin-quinone cyclophanes 1-4, 5-9, and 11-14, resp., with gradual variation of quinone acceptor strengths were synthesized. As key intermediates for building up the porphyrin-cyclophane skeleton the correspondingly 3,6-substituted 1,4-bis[4-(2-formylphenyl)-butyl]-2,5-dimethoxybenzenes 15-20 were synthesized. Condensation with pyrrole yielded the doubly bridged porphyrin cyclophanes 42-45; via the bis(dipyrrolylmethyl) derivatives 46-51 and 64-67 the single-bridged porphyrin cyclophanes 58-63 and 72-75 were obtained by acidic condensation with triethyl formate. Cleavage of the methoxy groups and oxidation yielded the corresponding porphyrin-quinone systems. Some magnesium and zinc complexes of these cyclophanes are described. Spectroscopic data (MS, 1H NMR) are reported in support of the proposed structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251017
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  • 7
    Electronic Resource
    Electronic Resource
    Photoinduced electron transfer in porphyrin-quinone cyclophanes, 5. Quinone-porphyrin-quinone and quinone-porphyrin-donor cyclophanes: Syntheses, structures and electron-transfer-related properties (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2275-2283 
    Details
    ISSN: 0009-2940
    Keywords: Photosynthesis models ; Photoinduced electron transfer ; Porphyrin-quinone cyclophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To study the structure dependence of photoinduced electron transfer between porphyrins and quinones the concept of a new family of porphyrin-quinone cyclophanes with vertical arrangements of porphyrin and quinone units is presented. The syntheses of the quinone-porphyrin-quinone cyclophane 1, the prototype of this series, and of the quinone-porphyrindonor cyclophanes 12 and 14 are described. Spectroscopic data are discussed with regard to the structures involved and in relation to electron-transfer reactions occurring in these systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251016
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  • 8
    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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  • 9
    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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  • 10
    Electronic Resource
    Electronic Resource
    Zinc Complexes of Porphyrin-Quinone Cyclophanes: Syntheses, Structures and Electron-Transfer-Related Properties (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 231-236 
    Details
    ISSN: 0009-2940
    Keywords: Zinc porphyrin complexes ; Porphyrin-quinone cyclophanes ; Photoinduced electron transfer ; Electron-transfer mechanism in metalloporphyrin-quinone cyclophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to increase the driving force for photoinduced electron-transfer reactions of porphyrin-quinone cyclophanes, the zinc complexes 3a-e and 4a-e were prepared from the corresponding cyclophanes of the 1 and 2 series. Electron-transfer-related properties like redox potentials and fluorescence spectra were determined for 3a-e and 4a-e. The X-ray structure analysis of 4a indicates that for the very fast and solvent-independent electron transfer in these systems a specific mechanism involving an interaction of a quinone carbonyl group with the zinc might be considered as an alternative to through-space electron-transfer.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270133
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