Comparison of the 13C (C = N) chemical shifts of substituted N‐(phenyl‐ethylene)‐anilines and substituted N‐(benzylidene)‐anilines

Cao, Zhongzhong; Cao, Chao‐Tun

doi:10.1002/poc.3450

Cited by 13 publications

(16 citation statements)

References 31 publications

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“…derivatives, [28,32] aryl Schiff bases, [39][40][41][42][43][44][45][46][47][48][49][50][51][52] and disubstituted pyrimidines. [53] Here, we also employed the excited-state substituent constant σ ex CC and Hammett electronic effect constant σ to quantify the Δν WSL of MC-AgNPs solutions.…”

Section: Effect Of Substituent On the Wavelength Shift Limit λ Wslmentioning

confidence: 99%

Effect of substituents on the UV spectra of supermolecular system: Silver nanoparticles with bi‐aryl Schiff bases containing hydroxyl

Cao

Cheng

Zhang

et al. 2018

J of Physical Organic Chem

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Effect of substituents on the ultraviolet (UV) spectra of supermolecular system involving silver nanoparticles (AgNPs) and Schiff bases was investigated. AgNPs and 49 samples of model compounds (MC), bi-aryl Schiff bases containing hydroxyl (XBAY, involving 4-OHArCH¼NArY, 2-OHArCH¼NArY, XArCH¼NAr-4′-OH, and XArCH¼NAr-2′-OH), were synthesized. The size of AgNPs was characterized by transmission electron microscopy (TEM), and the UV absorption spectra of AgNPs, XBAYs, and MC-AgNPs mixed solutions were measured, respectively. The results show that (1) the size of AgNPs is larger in MC-AgNPs solutions than that in AgNPs solution due to the distribution of MC molecules on the surface of AgNPs; (2) the UV absorption wavelength of XBAYs changes in the action of AgNPs and their wavelength shift exists limitation between XBAY and MC-AgNPs solutions; and (3) the wavelength shift limit of MC-AgNPs (λ WSL ) is influenced by the substituents X and Y and the position of hydroxyl OH. The wavenumber Δν WSL of λ WSL can be quantified by employing the excited-state substituent constant σ ex CC and Hammett constant σ of substituents X and Y. Comparing with the 4-OH, the 4′-OH makes the Δν WSL a red shift, whereas the 2′-OH, comparing with the 2-OH, makes the Δν WSL a blue shift.

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Section: Effect Of Substituent On the Wavelength Shift Limit λ Wslmentioning

confidence: 99%

Effect of substituents on the UV spectra of supermolecular system: Silver nanoparticles with bi‐aryl Schiff bases containing hydroxyl

Cao

Cheng

Zhang

et al. 2018

J of Physical Organic Chem

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“…Hammett parameter ( σ ), proposed by Hammett in 1937, is a well‐known molecular descriptor characterizing the ground‐state substituent effect. It has been extensively applied to the quantitative structure‐property relationship studies and exhibited good performances . The Hammett parameter for para‐position substituent is expressed as σ p , which consists of 2 parts, the inductive effect σ F and the resonance effect σ R .…”

Section: Experiments and Calculation Methodsmentioning

confidence: 99%

“…The excited‐state substituent constant

σ_{CC}^{ex}

is a molecular descriptor describing the stability of the excited state . It has been widely applied to the quantitative structure‐property relationship study of the ultraviolet maximum absorption, the NMR chemical shifts, and the reduction potentials . Here, we also take

σ_{CC}^{ex}

into consideration to correlate the UV absorption energy.…”

Section: Experiments and Calculation Methodsmentioning

confidence: 99%

Substituent effects on the UV absorption energy of 2,5‐disubstituted pyrimidines

Yuan

Chen

et al. 2018

J of Physical Organic Chem

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Pyrimidine-containing molecules have been extensively investigated in organic light emitting devices (OLEDs), solar cells, liquid crystals, and so on due to their perfect photoelectric properties. Ultraviolet (UV) absorption is one of the interesting photoelectric properties. Systematical study of the substituent effects on the UV absorption energy of pyrimidine derivatives will guide to design functional molecules with specific photoelectric properties. In this paper, thirty-seven 2-X-5-Y pyrimidines with various substituents (X/Y=NH 2 , CH 3 , OCH 3 , NMe 2 , CF 3 , NO 2 , Cl, Br, I) were synthesized, and their UV spectra were recorded in anhydrous ethanol. The maximum absorption wavelength λ max (nm) were obtained and converted to wavenumber ν max (cm -1 ) (ν max = 1/λ max ) for quantitative structure-property relationship study. Hammett parameters (σ, σ F , σ R ), electronegativity (χ), the excited-state substituent effect parameter (σ ex CC ), and the heavy atom effect indicator (D) were employed as descriptors characterizing the molecular structure. By stepwise regression, a 5-descriptor linear regression model was built as ν max = 35 864.8122 + 6743.7901σ R (X) + 8587.9937σ R (Y) − 2042.7280Δσ 2 + 1106.0034D(X) + 1451.8873χ(X) (R = 0.9861, S = 693.70, ARD = 1.49%, F = 218.68, R cv = 0.9775, S cv = 881.25, ARD cv = 1.82%, n = 37). The model is proved of good stability and predictive performance by leave-one-out cross validation. Compared with the benzylideneaniline derivatives with C═N bridge group, the substituent effects on the UV absorption energy of 2,5-disubstituted pyrimidines are quite different and much more complex. KEYWORDS 2,5-disubstituted pyrimidine, quantitative structure-property relationship, substituent effect, UV absorption

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“…In this work, the XPNY and XPEAY were synthesized according to the reports of Liu and Barluenga as shown in scheme . All the compounds were characterized by 1 H NMR, in which the confirmation of XPEAYs were carried out by employing the method of our previous work …”

Section: Experimental Sectionsmentioning

confidence: 99%

Influence of the side-group at C=N bridging bond of bis-aryl Schiff bases on the wavelength of absorption maximum of ultraviolet absorption spectra

Luo¹,

Cao²,

Cao³

et al. 2016

J. Phys. Org. Chem.

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The compounds N-(benzylidene)-anilines XArCH=NArY (XBAY), N-(phenyl-ethylene)-anilines XArC(CH 3 )=NArY (XPEAY) and N-phenyl-α-phenylnitrones XArCH=N(O)ArY (XPNY) have bridging group CH=N, C(CH 3 )=N and CH=N(O) respectively, in which the C(CH 3 )=N has a side-group methyl CH 3 at carbon end and the CH=N(O) has a side-group O atom at nitrogen end. In this work, a series of XPEAY and XPNY were synthesized, and their longest wavelength maximum λ max (nm) of ultraviolet absorption spectra were measured. Then the change regularity of the ν max (cm -1 , ν max =1/λ max ) of XPEAY and XPNY were investigated, and they were compared with that of XBAY (reported by ref.26). The results indicate: (1) There are no good linear relationships between the ν max of XBAYs and XPEAYs or XPNYs. (2) In case of a same set of X-Y group couples, the distribution of λ max of XPEAYs is larger than that of XPNYs. (3) The side-group CH 3 makes the effect of σ(X) larger than that of σ(Y) on the ν max of XPEAYs, whereas the O atom makes the effect of σ(Y) larger than that of σ(X) on the ν max of XPNYs. (4) The cross-interaction between X and Y has important effect on the all ν max . However, the cross-interaction between CH 3 and X/Y has not important effect on the ν max of XPEAY, and the cross-interaction between O and X/Y has not important effect on the ν max of XPNY.

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Comparison of the ¹³C (C = N) chemical shifts of substituted N‐(phenyl‐ethylene)‐anilines and substituted N‐(benzylidene)‐anilines

Cited by 13 publications

References 31 publications

Effect of substituents on the UV spectra of supermolecular system: Silver nanoparticles with bi‐aryl Schiff bases containing hydroxyl

Effect of substituents on the UV spectra of supermolecular system: Silver nanoparticles with bi‐aryl Schiff bases containing hydroxyl

Substituent effects on the UV absorption energy of 2,5‐disubstituted pyrimidines

Influence of the side-group at C=N bridging bond of bis-aryl Schiff bases on the wavelength of absorption maximum of ultraviolet absorption spectra

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