Substituent effects on 1H NMR spectra of 4‐and 4′‐substituted tras‐N‐benzylideneanilines in acidic solution

Odian, George; Yang, Nan‐Loh; Wei, Yen

doi:10.1002/mrc.1260231106

Cited by 20 publications

(9 citation statements)

References 29 publications

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“…On the other hand, NMR shielding is affected by the electron density, and the field of resonance increases with the increasing electron density of the protons and carbon nucleus in molecules [1,2]. So the NMR chemical shifts of CH=N (δ H (CH=N) and δ C (CH=N)) were always applied to investigate the substituent effects in past years [3][4][5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Substituent Effects on 13C NMR and 1H NMR Chemical Shifts of CH=N in Multi-substituted Benzylideneanilines

Cao¹,

Wang

2018

Chinese Journal of Chemical Physics

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Fifty-three samples of multi-substituted benzylideneanilines XArCH=NArYs (abbreviated XBAYs) were synthesized and their NMR spectra were determined. An extensional study of substituent effects on the 1 H NMR chemical shifts (δ H (CH=N)) and 13 C NMR chemical shifts (δ C (CH=N)) of the CH=N bridging group from di-substituted to multi-substituted XBAYs was made based on a total of 182 samples of XBAYs, together with the NMR data of other 129 samples of di-substituted XBAYs quoted from literatures. The results show that the substituent specific cross-interaction effect parameter (∆ (∑ σ) 2) plays an important role in quantifying the δ C (CH=N) values of XBAYs, but it is negligible for quantifying the δ H (CH=N) values; the other substituent parameters also present different influences on the δ C (CH=N) and δ H (CH=N). On the whole, the contributions of X and Y to the δ C (CH=N) of XBAYs are balanced, but the δ H (CH=N) values of XBAYs mainly rely on the contributions of X.

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Section: Introductionmentioning

confidence: 99%

Substituent Effects on 13C NMR and 1H NMR Chemical Shifts of CH=N in Multi-substituted Benzylideneanilines

Cao¹,

Wang

2018

Chinese Journal of Chemical Physics

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“…Changes of X and Y in XBAY can affect its molecular overall electron distribution and the properties of optoelectronic materials containing the molecule of XBAY. Therefore, the substituent effects on the performance of the CHN bridging group attained great interest in recent years …”

Section: Introductionmentioning

confidence: 99%

“…As we know, the NMR shielding is affected by the electron density, and the field of resonance increases with the increasing electron density of the protons and carbon nucleus in the molecule . So the NMR chemical shifts of CHN (δ H (CHN) and δ C (CHN)) were always applied by many researchers to study the substituent effects on the molecules in the past years . Echevarria et al have made sketchy studies about the 1 H NMR and 13 C NMR of CHN by employing 24 samples of substituted benzylideneanilines and discussed the linear relationship between the δ H (CHN) values or δ C (CHN) values and the Hammett substituent constant σ p .…”

Section: Introductionmentioning

confidence: 99%

Comparison of the substituent effects on the ¹³C NMR with the ¹H NMR chemical shifts of CHN in substituted benzylideneanilines

Wang

Cao

2015

Magnetic Reson in Chemistry

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Fifty-two samples of substituted benzylideneanilines XPhCH=NPhYs (XBAYs) were synthesized, and their NMR spectra were determined in this paper. Together with the NMR data of other 77 samples of XBAYs quoted from literatures, the (1) H NMR chemical shifts (δH (CH=N)) and (13) C NMR chemical shifts (δC (CH=N)) of the CH=N bridging group were investigated for total of 129 samples of XBAYs. The result shows that the δH (CH=N) and δC (CH=N) have no distinctive linear relationship, which is contrary to the theoretical thought that declared the δH (CH=N) values would increase as the δC (CH=N) values increase. With the in-depth analysis, we found that the effects of σF and σR of X/Y group on the δH (CH=N) and the δC (CH=N) are opposite; the effects of the substituent specific cross-interaction effect between X and Y (Δσ(2) ) on the δH (CH=N) and the δC (CH=N) are different; the contributions of parameters in the regression equations of the δH (CH=N) and the δC (CH=N) [Eqns and 7), respectively] also have an obvious difference.

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“…In fact, several recent studies on 13 C NMR demonstrated that the field of resonance increased with the increasing electron density of the carbon nucleus in the molecule . In order to explore the effect of substituent on the electronic distribution, concentrated investigations by means of 13 C NMR have been done . 13 C NMR studies have revealed that the overall electron distribution can be finely tuned through the electronic effects of remote substituents …”

Section: Introductionmentioning

confidence: 99%

Long‐range transmission of substituent effects on ¹³C NMR chemical shifts of imine carbon in benzylidene anilines

Fang

Cao

et al. 2012

J of Physical Organic Chem

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The 13 C NMR chemical shifts of six kinds of substituted benzylidene anilines, with different backbone conjugation length, have been used as a probe to investigate the long-range transmission of substituent effects. In this context, it was found that for substituents Y at the aniline unit, the transmission of the inductive and conjugative effects depend on the chemical bond numbers n (Y) between Y and the imine carbon, and the parameters n (Y) À2 s F (Y) and n (Y) À2 s R (Y) are suitable to scale the corrected inductive and conjugative effects, respectively. However, for substituents X, the chemical bond numbers n (X) between X and the imine carbon influences only the transmission of inductive effects of X, and the n (X) À2 s F (X) item is appropriate to evaluate the modified inductive effects of X. Similarly, Δs (cor) 2 was proposed to describe the transmitted effect of the cross-interaction effect. With the parameters n (X), and d C (parent), the d C (C = N) values of 181 samples can be well correlated. The correlation coefficient is 0.9957, and the standard derivation is only 0.23 ppm. Moreover, the multi-parameter correlation equation is predicted well the d C (C = N) of other 25 samples of designed conjugated benzylidene anilines.

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Substituent effects on ¹H NMR spectra of 4‐and 4′‐substituted tras‐N‐benzylideneanilines in acidic solution

Cited by 20 publications

References 29 publications

Substituent Effects on 13C NMR and 1H NMR Chemical Shifts of CH=N in Multi-substituted Benzylideneanilines

Substituent Effects on 13C NMR and 1H NMR Chemical Shifts of CH=N in Multi-substituted Benzylideneanilines

Comparison of the substituent effects on the ¹³C NMR with the ¹H NMR chemical shifts of CHN in substituted benzylideneanilines

Long‐range transmission of substituent effects on ¹³C NMR chemical shifts of imine carbon in benzylidene anilines

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Substituent effects on 1H NMR spectra of 4‐and 4′‐substituted tras‐N‐benzylideneanilines in acidic solution

Cited by 20 publications

References 29 publications

Substituent Effects on 13C NMR and 1H NMR Chemical Shifts of CH=N in Multi-substituted Benzylideneanilines

Substituent Effects on 13C NMR and 1H NMR Chemical Shifts of CH=N in Multi-substituted Benzylideneanilines

Comparison of the substituent effects on the 13C NMR with the 1H NMR chemical shifts of CHN in substituted benzylideneanilines

Long‐range transmission of substituent effects on 13C NMR chemical shifts of imine carbon in benzylidene anilines

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Resources

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Substituent effects on ¹H NMR spectra of 4‐and 4′‐substituted tras‐N‐benzylideneanilines in acidic solution

Comparison of the substituent effects on the ¹³C NMR with the ¹H NMR chemical shifts of CHN in substituted benzylideneanilines

Long‐range transmission of substituent effects on ¹³C NMR chemical shifts of imine carbon in benzylidene anilines