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  • 1990-1994  (2)
  • 1980-1984  (5)
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  • 1
    Electronic Resource
    Electronic Resource
    Halochrome Molekeln 3. Mitteilung [1]. Thermodynamische und kinetische Untersuchungen zum acidobasischen Verhalten substituierter 6,6-Diphenyl-6H-chromeno[4,3-b]indole (1980)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 63 (1980), S. 1284-1293 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Halochromic Molecules. Thermodynamics and Kinetics of the Acidobasic Behaviour of Substituted 6,6-Diphenyl-6H-Chromeno [4,3-b]IndolesThe complex halochromic behaviour of substituted 6, 6-Diphenyl-6 H-chromeno-[4,3-b]indoles was investigated by stopped flow techniques and spectrometric methods in 64% methanol/water mixtures at 25°. pK-values are determined, rates and mechanisms of coloration reaction are investigated and results are discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19800630519
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  • 2
    Electronic Resource
    Electronic Resource
    Polarographische Untersuchungen an symmetrischen Triazacarbocyaninen in Methanol (1983)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 661-668 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polarographic Investigations on Symmetrical Triazacarbocyanine Dyes in MethanolThe reduction mechanism of eleven symmetrical triazacarbocyanine dyes with different heterocycles in methanol (containing lithium chloride or lithium acetate/acetic acid) has been investigated by means of polarography, cyclic oscillopolarography and coulometry.The reduction occurs in a reversible to irreversible two electron transfer step, followed by an irreversible chemical step. Reduction potentials, transfer coefficients and specific currents have been measured and compared with properties measured in acetonitrile.The effect of substituents X has been studied on the compounds 1-ethyl-2-[3-(1-ethyl-6-X-1,2-dihydroquinolin-2-ylidene)-1-triazeno]-6-X-quinolinium tetrafluoroborate 1f(X) and 3-ethyl-2-[3-(3-ethyl-5-X-Δ4-1, 3-thiazolin-2-ylidene)-1-triazeno]-5-X-1, 3-thiazolium tetrafluoroborate 1g(X), and ρ-values of 0.20 and 0.40 V, respectively, have been found.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19830660228
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Azidinium-Salze. 25. Mitteilung24. Mitteilung: [1].. Symmetrische Azopyridinon-Farbsalze: Synthese, spektrophotometrische und acidobasische Eigenschaften, Metallkomplex-Bildung und kinetische Untersuchung der Azo-Kupplung (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 216-230 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Symmetrical Azopyridinone Dyes: Synthesis, Spectrophotometrical and Acidobasic Properties, Metal-Complex Formation and Kinetical Investigation of the Azo-Dye FormationThe 13 substituted symmetrical azopyridinone dyes 2a-n were synthesized and their VIS spectra measured. The pK*a values of some dyes and of pyridinone coupling components were determined in MeOH/H2O 64:36. The metal-complex formation of the dyes with Cd2+, Zn2+, Co2+, Ni2+, and Cu2+ was investigated, and complex-formation constants of the 1:1 complexes were determined in H2O for 2k (Table 2) and in dimethylformamide/H2O 1:1 for some other azopyridinone dyes (Table 3). The mechanism of the azo-dye formation was investigated and found to be much more complicated than expected. A mechanism of the coupling reaction was developed (see Scheme 4) and fitted by least-squares calculations.
    Notes: NO ABSTRACT.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19940770124
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  • 4
    Electronic Resource
    Electronic Resource
    Polarographische Untersuchungen an symmetrischen Triazacarbocyaninen in Acetonitril (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1522-1532 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polarographic Investigations on Symmetrical Triazacarbocyanine Dyes in Acetonitrile SolutionThe reduction behaviour of thirteen symmetrical triazacarbocyanine dyes with different heterocycles in acetonitrile solution has been investigated by means of dc- and ac-polarography, cyclic oscillopolarography and coulometry.The reduction mechanism has been found to be of the type eec with the first step being reversible and the second step being reversible to irreversible. Reduction potentials, transfer coefficients and specific currents of both steps have been measured (E1/2: -0,110 to -1.025 V vs. Ag/AgCl for the first step) and compared with known properties of carbocyanines and triazenium salts and to HMO calculations.The effect of substituents X has been studied on the compounds 1,3-diethyl-2-[(1,3-diethyl-5-X-benzimidazolin-2-yliden)triazenyl]-5-X-benzimidazolium-tetra-fluoroborate (1a (X)) and 3-ethyl-2-[(3-ethyl-5-X-Δ4-1,3-triazolin-2-yliden)triazenyl]-5-X-1,3-thiazolium-tetrafluoroborate (1g(X)), and p-values of 0,36 and 0,72 V, respectively, have been found.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19810640528
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Voltammetrische Untersuchungen der Oxydation der symmetrischen Triazacarbocyanine in Acetonitril (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 765-769 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Voltammetric Investigations on the Oxidation Step of Symmetrical Triazacarbocyanine Dyes in Acetonitrile SolutionThe oxidation behaviour of twelve symmetrical triazacarbocyanine dyes with different heterocycles in MeCN (containing tetrabutylammonium perchlorate) has been investigated by means of dc-, ac- and cyclic triangular wave voltammetry. The oxidation mechanism has been found to be of the type ec, with the electrochemical step being reversible to irreversible. Oxidation potentials and transfer coefficients have been measured (E1/2 1.60 to 2.12 V vs. Ag/AgCl) and compared with known properties of carbocyanines. The effect of substituents X has been studied on the compounds 1,3-diethyl-2-[3-(1,3-diethyl-5-X-benzimidazolin-2-ylidene)-1-triazeno]-5-X-benzimidazolium tetrafluoroborate ((1a(X)) and 3-ethyl-2-[3-ethyl-5-X-Δ4-1,3-thiazolin-2-ylidene)-1-triazeno]-5-X-1,3-thiazolium tetrafluoroborate (1g(X)), and ρ-values of 0.425 and 0.565 V, respectively, have been found.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670317
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  • 6
    Electronic Resource
    Electronic Resource
    Polarographische und voltammetrische Untersuchungen an symmetrischen Methin-, Azamethin- und Phosphamethincyaninen in Acetonitril (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 770-773 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polarographic Investigations on Symmetrical Methine-, Azamethine-, and Phosphamethinecyanine dyes in Acetonitrile SolutionThe reduction and oxidation behaviour of six symmetrical methine-, azamethine-, and phosphamethine dyes with different heterocycles in MeCN solutions has been investigated by menas of dc- and ac-polarography (DME, MDE and rotating Pt-electrode) and cyclic triangular wave voltammetry. The reduction and oxidation mechanism has been found to be of the type ec with the reduction and oxidation step being reversible to irreversible. Reduction and oxidation potentials, transfer coefficients, and specific currents have been measured and compared with known properties of methinecyanines, carbocyanines, and triazacarhocyanines.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670318
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  • 7
    Electronic Resource
    Electronic Resource
    Tetrazinodiheteroarene: ‘Charge-Transfer’-Komplexbildung mit Akzeptorverbindungen (1990)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 81-85 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Charge-Transfer Complexes of Tetrazinodiheteroarenes with Acceptor CompoundsThe formation of charge-transfer complexes and radical-ion pairs of donor compounds 1-6 with acceptor compounds 7-12 has been investigated by means of VIS/NIR-spectroscopic methods. The equilibrium constants KCT up to 1100M-1 for the donor/acceptor couple dipyrido[1,2-b:1,2′-e][1,2,4,5]tetrazine (2)/ethylenetetracarbonitrile (11) and spectra of the CT complexes have been determined in 1,2-dichloroethane solution at 25°. Results are discussed in relation to known CT-complex properties and to voltammetric redox-potentials E1/2.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19900730108
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