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  • 1
    Electronic Resource
    Electronic Resource
    Photoinduzierte Elektronenübertragungsreaktionen zwischen aromatischen Diazoniumkationen und Anionen (1985)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 399-410 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photoinduced Electron Transfer between Arenediazonium Cations and AnionsAnions X⊖ can act as donors in electron transfer reactions to photoexcited arenediazonium ions. The yield of the arene formed in this reaction increases with decreasing electrochemical oxidation potential EoxD of X⊖ (X⊖ = BPh4⊖, Br⊖, HOOC—COO⊖, Cl⊖, BF4⊖). The oxidized donor X· (Cl·, ·COO⊖) and aryl radicals Ar· benig intermediates of the reductive dediazoniation of ArN2⊖ can be detected by spin trapping with nitrosodurene (ND) and phenyl-tert-butylnitrone (PBN). A solvent effect in the electron transfer reaction is interpreted in terms of ion pairing, where the electron transfer is favored by preorientation and a short distance between the electron donor and the acceptor previous to excitation of ArN2⊖ by light.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19853270306
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  • 2
    Electronic Resource
    Electronic Resource
    Solvenseffekte bei der Photoinduzierten Elektronenübertragung von ungeladenen Donatoren auf Arendiazoniumsalze (1985)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 411-421 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solvent Effects in the Photoinduced Electron Transfer Reaction of Uncharged Donors with Arenediazonium SaltsIn the photochemical electron transfer reactions to arene diazonium salts no strong Coulomb forces arise but the rate constants possibly vary in dependence on the state of the diazonium salt (tight ion pair in nonpolar solvents or free diazonium cations). This problem is studied in the present work using anthracene and tetracene, respectively, as electron donors. They react in their S1 states diffusion-controlled with ion pairs ArN2⊖ BF4⊖, whereas the respective triplet reactions proceed up to 103 times more slowly. These rates are not significantly influenced by the dielectric properties of the solvent. Thus, ion pairing of the diazonium salts in solvents of low polarity has no screening effect on the electron transfer.This behavior is explained including electrostatic effects into the MARCUS theory of outer sphere electron transfer processes. No indication of a Marcus inverted region was found.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19853270307
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  • 3
    Electronic Resource
    Electronic Resource
    Photochemical Dediazoniation of Arene Diazonium Salts sensitized by zink meso-tetraphenyl porphyrinProfessor Dr.-Ing. Dr.h.c. Eberhard Leibnitz zum 75. Geburtstage gewidmet (1985)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 21-34 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photoexcited zink tetraphenylporphyrin (ZnTPP) reacts with arene diazonium salts via electron transfer according to the oxidation mechanism. This is proved by ESR spectroscopy of ZnTPP+ formed and the fact that N2 and ZnTPP+ are formed in a molar ratio.Due to very different life-times of1(ZnTPP)* and 3(ZnTPP)* it is possible to differentiate between singlet and triplet electron transfer reactions using different diazonium salt concentrations. In this way, the respective quenching constants are determined by means of flash spectroscopy.Due to electron back transfer the singlet reaction at high concentrations of diazonium salts (0.1M) is inefficient (quantum yield 0.1), whereas back electron transfer is symmetry-forbidden in the triplet reaction which, therefore, proceeds with high quantum yields, mearly reaching the ISC quantum yield.From differences between the triplet quenching constants determined by flash spectroscopy and from product quantum yields, respectively, and from corresponding kinetic models it is concluded that the triplet reaction proceeds via a reversibly formed triplet exciplex.Complexes of meso tetraphenyl porphyrin containing Pb(II), Sn(IV), Mn(II), Ni(II), Cu(II) and Fe(III), respectively, have lower sensitization activities decreasing in the order, given in the text.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19853270105
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  • 4
    Electronic Resource
    Electronic Resource
    Eberson, L.: Electron transfer reactions in organic chemistry. 234 S., 65 Abb., 32 Tab., 17 × 25 cm. Berlin, Heidelberg, New York, London, Paris, Tokyo: Springer-Verlag 1987. (Reactivity and Structure. Concepts in Organic Chemistry, Vol. 25). Leinen, 128,-DM (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 175-176 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310130
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  • 5
    Electronic Resource
    Electronic Resource
    Photoreduction of Methyleneblue by the two-equivalent electron donor N-methyl-9-phenylacridane and the use of the system for the spectrally sensitized dediazoniation of p-N,N-dimethylamino benzenediazonium tetrafluoroborate (1990)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 651-657 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photoreduction of methyleneblue by N-methyl-9-phenylacridane (ACH) is studied in acetonitrile by means of flash photolysis and quantum yields. In the first step, due to fast proton shift within the original electron transfer product protonated semi-methyleneblue MBH.+ and the deprotonated donor radical (N-methyl-9-phenylacridanyl radical AC·) are formed with a rate constant of 2×108 M-1 s-1. In this radical pair a second electron is transferred very fast from AC· to MBH.+ with a rate constant ke2 ≈ 1010 s-1 to form leuco-methyleneblue and N-methyl-9-phenyl-acridinium salt (AC+). About 80% of the two-equivalent reduction product, leuco-methyleneblue, are formed within the first solvent cage during the flash. The maximum quantum yields of photoreduction approach ϕisc of MB+ as expected for a two-equivalent reduction reaction.The out-of-cage reaction consists of the known disproportionation of the protonated semi-methyleneblue MBH.+ and its reduction by the N-methyl-9-phenylacridanyl radical AC·. From the decay kinetics kred = 3×109 M-1 s-1 and kdis = 8×108 M-1 s-1 is derived.The system sensitizes the dediazoniation of p-N,N-dimethylamino benzenediazonium tetrafluoroborate efficiently even at very low diazonium salt concentrations (Φ = 0.6).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19903320510
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  • 6
    Electronic Resource
    Electronic Resource
    Determination of the Dipole Moment of the Charge-Shift Triplet Exciplex from zinc phthalocyanine tetrasulfomorpholide and p-methoxy-benzenediazonium tetrafluoroborateDedicated to Prof. Dr. M. Schulz on the occasion of his 60th birthday (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 989-994 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Triplet exciplexes are known to have usually relatively low polarities, in contrast to singlet exciplexes. It is shown that triplet quenching rate constants of the title system can be used to determine the exciplex dipole moment if it is (plausibly) assumed that the dissociation rate constants of charge-shift exciplexes only depend on the viscosity but not on the polarity of the solvent.The quenching rate constants kq of the title system in various acetonitrile/acetone or acetonitrile/ethylacetate mixtures are determined and treated by an adapted McRAE equation developed for UV-VIS absorption spectroscopic data.The dipole moment of p-methoxy-benzenediazonium tetrafluoroborate necessary for the solution of the McRAE equation is estimated by a Hammett correlation of known data which gives by extrapolation μ(p-MeO—C6H4N2⊕BF4⊖) = 31.4 × 10-30 Cm (9.4 Debye). Using this value and a cavity radius of 3.7 × 10-10m (cp. [1]) μex3(ZnPcTSM…p-MeO-C6H4N2⊕BF4⊖)* = 16.0 × 10-30 cm (4.8 Debye) is obtained. According to this value the triplet exciplex studied has a lower polarity than the starting diazonium salt.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310613
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  • 7
    Electronic Resource
    Electronic Resource
    Spectral Sensitization of Dediazoniation by the 2-electron-transfer system meso-tetraphenylporphinato-dichlorostannate(IV)/10-methyl-9-Phenyl-9.10-dihydro-acridine (1990)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 241-250 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photoreduction of meso-tetraphenylporphinatodichlorostannate(IV) (SnCl2TPP) by 9-phenyl-10-methyl-9,10-dihydro-acridine (ACH) in 1,2-dichloroethane/acetonitrile 1:1 (v/v) under argon proceeds only with a low quantum yield in spite of the fact that ACH is in other cases an excellent 2-electron donor. The reason may be the formation of a triplet exciplex which opens a new deactivation channel. Evidence for such an exciplex is given by means of the WARE treatment of flash-photolytic experiments and quantum yields of dediazoniation, Keq ≈ 650 M-1 and τexc = 46 μs.The exciplex reacts fast with p-N,N-dimethylamino-benzenediazonium tetrafluoroborate (kr = 4.1 × 108 M-1 s-1) under electron transfer leading to dediazoniation. At high ACH concentrations (8 × 10-3 M) the dediazoniation gives even at very low diazonium salt concentrations (≈ 4 × 10-5 M) quantum yields as high as 1.95 (0.37 stemming from sensitization by the SnCl2 complex of tetraphenylchlorine present as an impurity of SnCl2TPP. SnCl2TPP) remains unchanged during the sensitization reaction, i.e. the process is fully photocatalytic.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19903320216
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  • 8
    Electronic Resource
    Electronic Resource
    Tietze, L. F. Eicher, Th: Reaktionen und Synthesen im organisch-chemischen Praktikum. 592 S., Format 16×23 cm, Stuttgart-New york:Georg Thieme Verlag 1981n, Paperback preis 54,- DM (1983)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 325 (1983), S. 1047-1048 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19833250626
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  • 9
    Electronic Resource
    Electronic Resource
    Photoinduzierte Elektronentransfer-Reaktionen von Komplexen der Arendiazoniumsalze mit KronenethernVortrag auf der Hauptjahrestagung der Chemischen Gesellschaft der DDR 1980 in Karl-Marx-Stadt. (1984)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 326 (1984), S. 92-100 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photoinduced Electron Transfer-Reactions of Arenediazonium Ions Complexed with Crown EthersThe photolysis (full light of a medium pressure Hg-lamp) of p-methylbenzenediazonium-tetrafluoroborate in the presence of the crown ether 18-crown-6 (1) yields mainly the products of a heterolytic dediazoniation via arene cations as intermediates. The quantum yield ϕges of the photolysis from p-methoxybenzenediazonium-tetrafluoroborat in CH2Cl2 decreases in the presence of 18- crowns-6 (1) from 0.66 to 0.08. In contrast to 1, the photolysis of arenediazonium salts in the presence of dibenzo-18-crown-6 (3) yields mainly the products of a homolytic dediazoniation as a consequence of an electron transfer from 3 to the diazonium ion. ϕges of this reaction increases with decreasing wavelength of the exciting light from 0.09 (436 nm) to 0.32 (366 nm). this wavelength dependence is explained by formation of a correlated radical pair after excitation. In agreement with this situation a photo-CIDNP-effect is observed in the 15N-n.m.r.-spectra of isotopically labeled arenediazonium salts complexed by 3 and benzo-18-crown-6(2). No photo-CIDNP-effect is observed in the presence of 1. This different behaviour of the EDA-complexes formed by arenediazonium salts with the two different groups of crown ethers 1 and 2, 3 is discussed as a control of the electron transfer-reaction by the structure of the frontier orbitals.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19843260114
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  • 10
    Electronic Resource
    Electronic Resource
    Fluoreszenzlöschung und Excimerenbildung von Pyren-3-sulfonat in wäßrigen Lösungen von Polydimethyldiallylammoniumchlorid (1987)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 329 (1987), S. 87-94 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quenching of Fluorescence and Excimer Formation of Sodiumpyren-3-sulfonate in Aqueous Solutions of Polydimethyldiallylammonium ChlorideThe fluorescence spectra and lifetimes of sodium-pyren-3-sulfonate have been measured in the presence of polydimethyldiallylammonium chloride. It is shown, that the excimer formation by static self-quenching of fluorescence of the pyren-3-sulfonate is based on the cooperative effect of the macroion. The association constants of interaction between the aromatic compound and the polycation are determined. Presence of diazoniumcations leads to quenching of fluorescence of pyren-3-sulfonate in both the polyelectrolyte and aqueous phases. The quenching constants are discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19873290112
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