Substituent Effects on Chemical Shifts in the Sidechains of Aromatic Systems

Craik, David J.; Brownlee, Robert T. C.

doi:10.1002/9780470171936.ch1

Cited by 111 publications

(12 citation statements)

References 154 publications

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“…imino derivatives (Figs. S24 and S25) could give valuable information in the analysis/quantification of the contribution of polar (field/inductive) and polarization effects [45] at the carbon atom of interest. The structural similarity of series 1-7 offers a possibility to compare correlation results in relation to structural difference of heterocyclic structure attached at C3 atom (Fig.…”

Section: Comparative Lfer Analysis Of Nmr For Azomethine Carbon Of Selected Imino Seriesmentioning

confidence: 99%

“…The correlation results for the azomethine carbon (Table 8) indicate that, not only electronic properties of heteroatoms, but also geometrical characteristics influence their specific behavior. Introduction of methyl group, present in series 6 and 7, exerts appropriate steric effect and positive inductive effect supporting imino type resonance [44][45][46][47].…”

Section: Comparative Lfer Analysis Of Nmr For Azomethine Carbon Of Selected Imino Seriesmentioning

confidence: 99%

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Detailed solvent, structural, quantum chemical study and antimicrobial activity of isatin Schiff base

Brkić

Božić

Marinković

et al. 2018

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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The ratios of E/Z isomers of sixteen synthesized 1,3-dihydro-3-(substituted phenylimino)-2H-indol-2-one were studied using experimental and theoretical methodology. Linear solvation energy relationships (LSER) rationalized solvent influence of the solvent-solute interactions on the UV-Vis absorption maxima shifts (ν) of both geometrical isomers using the Kamlet-Taft equation. Linear free energy relationships (LFER) in the form of single substituent parameter equation (SSP) was used to analyze substituent effect on pK, NMR chemical shifts and ν values. Electron charge density was obtained by the use of Quantum Theory of Atoms in Molecules, i.e. Bader's analysis. The substituent and solvent effect on intramolecular charge transfer (ICT) were interpreted with the aid of time-dependent density functional (TD-DFT) method. Additionally, the results of TD-DFT calculations quantified the efficiency of ICT from the calculated charge-transfer distance (D) and amount of transferred charge (Q). The antimicrobial activity was evaluated using broth microdilution method. 3D QSAR modeling was used to demonstrate the influence of substituents effect as well as molecule geometry on antimicrobial activity.

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Section: Comparative Lfer Analysis Of Nmr For Azomethine Carbon Of Selected Imino Seriesmentioning

confidence: 99%

Section: Comparative Lfer Analysis Of Nmr For Azomethine Carbon Of Selected Imino Seriesmentioning

confidence: 99%

Detailed solvent, structural, quantum chemical study and antimicrobial activity of isatin Schiff base

Brkić

Božić

Marinković

et al. 2018

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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“…Therefore, one-third of the resonance effect of the parasubstituted benzene ring may be detected at the meta-carbon atom. Also, Hansch et al 39 correlated σ m with the substituent constants σ F and σ R derived from 19 F NMR measurements of substituted fluorobenzene. However, the amount of detected resonance effect also depends on the studied property; the resonance effect for an equilibrium constant will be different from that for charge or 13 C SCS measurements.…”

Section: Resultsmentioning

confidence: 99%

“…They observed the same trend in molecular orbital calculations of the electron densities at these two vinyl carbons. Craik et al 19 and Bromilow et al 4 investigated the 13 C SCS in 1,4-disubstituted benzenes. They constructed a DSP model which confirmed the existence of the π-polarization, and they rationalized the variation of 13 C SCS accordingly.…”

Section: Introductionmentioning

confidence: 99%

Substituent Effect Study for ¹³C_β SCS in a Meta-Styrene Series. Reynolds Dual Substituent Parameter Model Investigation

2021

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This article investigates the transmission of the metasubstituent, X, effect to the carbon β (C β ) of 17 different styrenes (X− C 6 H 4 −CHCYZ) using the literature 13 C substituent chemical shift (SCS) of C β . The 13 C SCSs of C β were modeled by Reynolds substituent field σ F and resonance σ R constants. The model is considered a dual substituent parameter model, SCSThe coefficients of determination of the modeled 13 C SCS for the 17 series fall between 0.9878 and 0.9983. The π-polarization concept was used to rationalize the field and resonance effects felt at C β . The ρ F values of the meta-series were all lower than the para-series ρ F values. The substituent field effect transmits to C β from C ipso . The substituent resonance effect transmits from C ipso to C β initially through the π-bond to C ortho and C para , next to the side chain, and then the generated charge will induce the vinyl group via π-polarization. The ρ F felt at C β was almost double the ρ R when compared with the short distance between C meta and C β , as opposed to C ortho and C para . Stabilization of the π-polarization of the vinyl group will increase, with the field and resonance effects felt at C β and vice versa.

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“…The ρ I value at N atom has a positive sign and a magnitude roughly quintuple that of the ρ I value at Cα. It is interesting to note that a DSP analysis of 13 CNMR substituted chemical shifts (SCS) for the styrene derivatives dose show a differing polar effect [16]. Because of the ability of the nitron group to conjugate with adjacent systems, the electron distribution of the aromatic and nitron systems are closely interrelated and it is therefore reasonable to ask why a positive ρ I value, indicative of polarization as in structure 2a, is consistently observed for the C α site, when it might be expected that the whole conjugated π system should be polarized as a unit, as in structures 2b or 2c The type of polarization, shown in structure 2b is called extended polarization and results in charge density at C α having a similar sign to those at the nitrogen atom but of a smaller magnitude.…”

Section: Taft's Equationmentioning

confidence: 99%

Substituent Electronic Effects on the Mulliken Charges of N-(4-Substituted Benzylidene)-1-Phenylmethanamine Oxide Elucidated by DFT Calculations

Essa

2010

J. Sci. Res.

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Calculations based on density functional methods are carried out to investigate the effects of a variety of substituents (NMe 2 , OMe, Me, F, H, Cl, CN, NO 2 ) on the Mulliken charges (Q M ) for C α and N atoms of N-(4-Substituted benzylidene)-1-phenylmethanamine oxide using Hammett's MSP and Taft's DSP equations. The MSP and DSP correlations give normal substituent effect at C α and N atom sites. This can be attributed to extended π-polarization, which predominates over the localized π-polarization.

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Substituent Effects on Chemical Shifts in the Sidechains of Aromatic Systems

Cited by 111 publications

References 154 publications

Detailed solvent, structural, quantum chemical study and antimicrobial activity of isatin Schiff base

Detailed solvent, structural, quantum chemical study and antimicrobial activity of isatin Schiff base

Substituent Effect Study for ¹³C_β SCS in a Meta-Styrene Series. Reynolds Dual Substituent Parameter Model Investigation

Substituent Electronic Effects on the Mulliken Charges of N-(4-Substituted Benzylidene)-1-Phenylmethanamine Oxide Elucidated by DFT Calculations

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Substituent Effects on Chemical Shifts in the Sidechains of Aromatic Systems

Cited by 111 publications

References 154 publications

Detailed solvent, structural, quantum chemical study and antimicrobial activity of isatin Schiff base

Detailed solvent, structural, quantum chemical study and antimicrobial activity of isatin Schiff base

Substituent Effect Study for 13Cβ SCS in a Meta-Styrene Series. Reynolds Dual Substituent Parameter Model Investigation

Substituent Electronic Effects on the Mulliken Charges of N-(4-Substituted Benzylidene)-1-Phenylmethanamine Oxide Elucidated by DFT Calculations

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Substituent Effect Study for ¹³C_β SCS in a Meta-Styrene Series. Reynolds Dual Substituent Parameter Model Investigation