Topic
Mesomeric effect
About: Mesomeric effect is a research topic. Over the lifetime, 182 publications have been published within this topic receiving 3590 citations.
Papers published on a yearly basis
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Papers
TL;DR: In this paper, the influence of donor and acceptor substituents on the second and third order hyperpolarizabilities β and γ of large conjugated molecules such as stilbene and styrene derivatives was investigated.
Abstract: We have investigated the influence of donor and acceptor substituents on the second and third order hyperpolarizabilities β and γ of large conjugated molecules such as stilbene and styrene derivatives. This was performed by two independent measurements of β and γ using the techniques of dc electric‐field induced second‐harmonic generation and tunable four‐wave mixing in liquids and solutions. For trans−stilbene derivatives, β and γ are typically 10 times larger than for the corresponding benzene compounds, and are strongly correlated with the mesomeric effect of the substituents. A series of disubstituted molecules with strong donor–acceptor intramolecular charge transfer exhibit very large β, and it is shown that this enhancement can be predicted from the basic properties of the first electronic excited state.
1,502 citations
TL;DR: The optimized geometry of BBC using density functional theory shows that the energetically favored chair conformation is not observed for central cyclohexanone ring and is found to possess a nearly 'half chair' conformation and shows less expansion of the angles and more rotation about the bonds.
182 citations
TL;DR: In this paper, a series of R3SnO2CR' compounds, where R = Me (1), Et (2), Bu-n (3), Ph (4), and cHex (5) and R'CO2 is the carboxylate residue of 2-[(E)-2-(2-hydroxy-5-methylphenyl)-1-diazenyl]benzoic zoic acid, has been shown by multinuclear magnetic resonance studies to be monomeric in solution.
135 citations
TL;DR: In this article, the influence of 2-methyl-6-tert.butyl substitution on certain properties of compounds such as nitrobenzene, aniline, N-methylaniline and acetanilide was discussed.
Abstract: Following up earlier work, this paper discusses the influence of 2-methyl-6-tert.butyl substitution and/or 2,6-di-tert.butyl substitution on certain properties of compounds such as nitrobenzene, aniline, N-methylaniline, N,N-dimethylaniline, acetanilide, 4-nitro-aniline, and 4-nitro-acetanilide.
For the derivatives of nitrobenzene, N,N-dimethylaniline, and acetanilide the electronic absorption spectra indicate a complete or almost complete elimination of the mesomeric interaction. In contrast with this it has to be concluded for all the primary amines investigated that the mesomerism is fully developed; in the relevant discussion the vectorial treatment of absorption Intensities has been of decisive importance. The secondary amines take up an intermediate position; in these cases, owing to the pyramidal configuration of the nitrogen atom, the angle of twist cannot be forced to values exceeding about 60°.
The basic strength of 2,6-di-tert.butyl-substituted primary amines is lower by a factor of about 108 than might be expected on the basis of the electrical effects of the alkyl groups; the basic strength of 2-methyl-6-tert.butyl-substituted N,N-dimethylanilines is lower by a factor of about 106 than might be expected on the basis of the electrical effects of the alkyl groups and the steric inhibition of the mesomerism present in these compounds. These reductions of the basic strength have been ascribed to steric hindrance to solvation.
The basic strength of 3,5-di-tert.butyl-4-nitroaniline confirms previously obtained information on the quantitative significance of the inductive and the mesomeric effect of the nitro group in 4-nitroaniline as well as on the meta/para ratio of the inductive effect.
98 citations
TL;DR: In this article, a number of simple prototype reactions involving radicals and atoms and ethylenic bonds were investigated and it was found that the heat of reactions is a most important factor in determining the activation energies of such reactions and this result was extended to a wide variety of substituted radicals and monomers.
Abstract: By using the methods which have been developed to describe the activation energy of chemical reactions in terms of bond energies and the repulsing energies between reacting centers, the factors influencing the activation energies of reactions between radicals and monomers are discussed. Calculations are reported on a number of simple prototype reactions involving radicals and atoms and ethylenic bonds. It is found that the heat of reactions is a most important factor in determining the activation energies of such reactions and this result is extended to a wide variety of substituted radicals and monomers. The variation in the heat of reaction is expressed in terms of the resonance energies of the reacting radicals and molecules. Another important factor is the energy of repulsion between the reacting centers, and this energy is affected by (a) the charge distribution on the reacting centers and (b) the steric effect of substituent groups. The effect of substituents on the charge distribution is discussed in terms of the molecular orbital method, an attempt being made to distinguish between the influence on the π electrons of the inductive and mesomeric effect of substituents.
83 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 4 |
| 2020 | 5 |
| 2019 | 4 |
| 2018 | 2 |
| 2017 | 2 |
| 2016 | 4 |