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  • 1980-1984  (16)
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  • 1
    Electronic Resource
    Electronic Resource
    Kinetics of diffusion-controlled reactions of particles with a nonuniform reactive surface (1981)
    Springer
    Theoretical and experimental chemistry 16 (1981), S. 538-542 
    Details
    ISSN: 1573-935X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00526979
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  • 2
    Electronic Resource
    Electronic Resource
    Pulse photolysis study of formation of ion-radicals in quenching of triplets of quinones by electron donors (1982)
    Springer
    Russian chemical bulletin 31 (1982), S. 466-470 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions 1. Values have been obtained for the rate constants of radiationless deactivation of triplet exciplexes to the ground state and the distances between ion-radicals in ion-radical pairs formed in the quenching of triplet states of quinones by electron donors. 2. The distances between the ion-radicals in collision complexes of quinone anion-radicals and electron donor cation-radicals are only slightly dependent on the structures of the donor and acceptor in nonsolvating solvents, and amount to 10–12 A. Alcohol molecules form hydrogen bonds with the quinone anion-radicals, leading to an increase in the distance between radicals in the pair. 3. For the rate constants of radiationless deactivation of triplet exciplexes to the ground state, the following rule is observed: the rate constant increases with decreasing level of the energy of the triplet exciplex, i.e., with decreasing energy interval of the transition. The solvation of triplet exciplexes by alcohol molecules leads to an increase in the rate constants of deactivation of triplet exciplexes to the ground state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00949761
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  • 3
    Electronic Resource
    Electronic Resource
    Quenching of duroquinone by aromatic donors of electron and hydrogen atom (1982)
    Springer
    Russian chemical bulletin 31 (1982), S. 890-894 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions 1. In the quenching of the triplet state of duroquinone by strong aromatic electron donors, which goes forward with diffusional rate constants, electron transfer is effected. Weak aromatic electron donors in nonsolvating solvents quench the duroquinone triplet through the formation of weak donor-acceptor complexes, and in alcohols through an electron transfer mechanism. 2. In the quenching of a triplet state of duroquinone by secondary aromatic amines and phenols, a hydrogen atom is transferred; this is accomplished in nonpolar exciplexes, or it may be a result of proton transfer in a radical pair that has been formed after electron transfer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00949938
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  • 4
    Electronic Resource
    Electronic Resource
    Quenching of triplet states of quinones by phenols (1984)
    Springer
    Russian chemical bulletin 33 (1984), S. 702-708 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions 1. The kinetics of quenching the triplet states of quinones by phenols in liquid solutions are determined by the process of forming a hydrogen-bond complex between the triplet and the quenching agent and by transfer of a hydrogen atom in this complex. 2. The isotope effect for the rate constant in quenching triplet states of quinones by phenols first increases with increasing acidity of the phenol, and then drops off. 3. The quantum yields of phenoxyl and semiquinone radicals formed by quenching triplet states of quinones by phenols are usually close to 100%, In quenching by phenols with strong acidic properties, the quantum yield of the radicals is lower if the triplet state of the quinone has a low energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00947818
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of the viscosity of the solvent on the kinetics of quenching of the triplet state of anthanthrone by aromatic electron and hydrogen atom donors (1984)
    Springer
    Russian chemical bulletin 33 (1984), S. 1160-1164 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions 1. The dependences of the rate constants of quenching of the triplet state of anthanthrone by aromatic electron and hydrogen atom donors on the viscosity of the solvent were obtained. The diffusion and kinetic elementary stages of the quenching reaction were distinguished, and the rate constants of these stages were determined. 2. The reaction of formation of a complex with a hydrogen bond, which is an intermediate stage in quenching of the triplet state of anthanthrone by phenols, is controlled by diffusion but is characterized by relatively low rate constants, since rigorous mutual orientation of the reagents is required in this reaction. 3. The rate constant of formation of an intermediate complex with a hydrogen bond between the triplet of anthanthrone and phenols decreases with an increase in the strength of the hydrogen bond, which requires a more rigorous mutual orientation of the reagents. 4. The rate constant of transfer of a hydrogen atom from phenol to the triplet of anthanthrone in a complex with a hydrogen bond decreases when electronegative substituants are introduced in the phenol molecule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00948979
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  • 6
    Electronic Resource
    Electronic Resource
    Mechanism of quenching of triplet exciplexes by aromatic hydrogen-atom donors (1984)
    Springer
    Russian chemical bulletin 33 (1984), S. 1603-1607 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions 1. In the quenching of triplet exciplexes of quinones by phenols and secondary aromatic amines, hydrogen atom transfer is accomplished with the formation of phenoxyl or aminyl radicals. The radical yields depend on the prototropic equilibrium in the complexes. The complex consisting of neutral particles dissociates into radicals; however, the main channel for the destruction of the complex containing the charged particles is intercombinational conversion to the ground state. 2. The addition of an alcohol to the nonpolar solvent lowers the yield of radicals in quenching triplet exciplexes of quinones by phenols and secondary aromatic amines. Specific solvation of the complex formed after hydrogen atom transfer shifts the prototropic equilibrium in this complex toward the complex with charged particles. Here, the main role is played by solvation of the electron donor introduced into the composition of the triplet exciplex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00959189
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of the solvent viscosity on the rate of phenoxyl radical recombination (1980)
    Springer
    Russian chemical bulletin 29 (1980), S. 182-186 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions 1. The relation between the rate of dimerization of various phenoxyl radicals and the viscosity of the medium has been studied. 2. A generalization of the contact model of the liquid-phase bimolecular reaction has been described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00961742
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of solvent and substituents on electron and hydrogen atom transfer in quenching of quinone triplets by secondary aromatic amines (1983)
    Springer
    Russian chemical bulletin 32 (1983), S. 251-257 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions 1. Hydrogen-atom transfer in quenching of triplet states of quinones by secondary aromatic amines takes place by establishment of prototropic equilibrium in the radical pair due to electron transfer. Electron transfer is the first event in quenching. 2. The characteristics of the effect of the substituents and the medium on the position of prototropic equilibrium between radical pairs of neutral and charged radicals were established. A V-shaped dependence of the equilibrium constant on dielectric permeability in nonsolvating solvents was found. The specific solvation of hydroxyl-containing solvents results in a significant shift in the equilibrium toward formation of ion-radicals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00957926
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  • 9
    Electronic Resource
    Electronic Resource
    Study of excited states in phenyl-substituted p-benzoquinones by laser photolysis and CNDO/S calculation (1980)
    Springer
    Russian chemical bulletin 29 (1980), S. 1087-1091 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions 1. The introduction of phenyl substituants into the p-benzoquinone molecule lowers the energy of the lowest singlet and triplet ππ* states. The lowest triplet states for 2-phenyl- and 2,6-diphenyl-l,4-benzoquinone are ππ* states. 2. The lifetime of triplet aryl-substituted p-benzoquinones in liquid solutions increases as the energy of the lowest triplet ππ* state decreases owing to an increase in the contribution from this state to the lowest triplet state of the quinone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00949159
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  • 10
    Electronic Resource
    Electronic Resource
    Investigation of the mechanism of electron and hydrogen-atom transfer during quenching of the triplet state of 2,6-diphenyl-1,4-benzoquinone by aromatic amines using the methods of laser photolysis and CIDNP (1980)
    Springer
    Russian chemical bulletin 29 (1980), S. 1919-1924 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions 1. Using the methods of laser photolysis and CIDNP the mechanism of the photoreduction of 2,6-diphenyl-1,4-benzoquinone by diphenylamine has been established and the kinetics and spectral characteristics of the short-lived intermediate products formed during the photo-reduction process have been determined. 2. Quenching of triplet 2,6-diphenyl-1,4-benzoquinone by diphenylamine occurs by an electron and H-atom transfer mechanism, both processes taking place in an encounter complex and being concurrent with one another. 3. The nature of the short-lived intermediate products formed during quenching of the triplet 2,6-diphenyl-1,4-benzoquinone by aromatic amines in a weakly polar medium has been established. When quenching with diphenylamine a nondissociated ion-radical pair is formed, but with triphenylamine a triplet exciplex is formed. 4. The predominant role of the triplet mechanism in giving rise to CIDNP in ion-radical reactions which occur in weakly polar media has been confirmed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00949657
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