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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 1H NMR chemical shifts (δH(CH=N)) and 13C NMR chemical shifts (δC(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 (Δ(Σσ)2)plays an important role in quantifying the δC(CH=N) values of XBAYs, but it is negligible for quantifying the δH(CH=N) values; the other substituent parameters also present different influences on the δC(CH=N) and δH(CH=N). On the whole, the contributions of X and Y to the δC(CH=N) of XBAYs are balanced, but the δH(CH=N) values of XBAYs mainly rely on the contributions of X.  相似文献
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合成了49个3,4''/4,3''/3,3''-二取代氮苄叉苯胺化合物,采用循环伏安法测得了其还原电位,并对取代基在还原电位中的影响进行了研究. 得到了一个四参数(取代基X的Hammett参数σ(X)、取代基Y的Hammett参数σ(Y)、取代基X的激发态取代基参数σCCex和交叉相互作用项ΔσCCex)的最优回归方程. 结果表明含间位取代基的氮苄叉苯胺还原电位中的取代基效应与双对位取代的氮苄叉苯胺还原电位中的取代基效应是不同的. 对于3,4''/4,3''/3,3''-二取代氮苄叉苯胺来说,取代基的诱导效应和共轭效应的作用可以合并,所以在回归方程中应用了σ(X) 和σ(Y),另外,取代基X和Y间的交叉相互作用项也起到了重要作用. 相比于4,4''-二取代的氮苄叉苯胺,取代基X对3,4''/4,3''/3,3''-二取代氮苄叉苯胺还原电位的贡献要小一些,Y 对3,4''/4,3''/3,3''-二取代氮苄叉苯胺还原电位的贡献要大一些. 总之,不管是4,4''-二取代氮苄叉苯胺还是3,4''/4,3''/3,3''-二取代氮苄叉苯胺,取代基X对其还原电位的贡献大于Y的贡献.  相似文献
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Six series of styrene derivatives XCH═CHArY (total of 65) containing the styrene parent molecular skeleton were synthesized (here, Y is OMe, Me, H, F, Cl, CF3, CN, and NO2, and X is 2‐furyl, 3‐furyl, 2′‐methyl‐2‐furyl, 2‐thienyl, 3‐thienyl, and 2′‐methyl‐2‐theniyl). Their ultraviolet absorption spectra were measured in anhydrous ethanol, and their wavelength of absorption maximum λmax was recorded. For the wavenumber νmax (cm−1, νmax = 1/λmax) of the obtained λmax, a quantitative correlation analysis was performed, and 6 excited‐state substituent constants of groups X were obtained by means of curve‐fitting method. Taking the νmax values of total 90 compounds of styrene derivatives as a data set (including 25 compounds from reference and 65 compounds of this work), a quantitative correlation analysis was performed, and the reliability of the obtained was verified. In addition, 12 samples of disubstituted Schiff bases (XCH═NArY) involving the above groups X were synthesized, and their νmax values were recorded. Using these 12 νmax together with the 14 νmax values of Schiff bases taken from reference (total of 26 compounds), it was further verified that the values are reliable by means of quantitative correlation method.  相似文献
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Two sets of bis‐aryl Schiff bases that contain 4(or 4′)‐OH and 2(or 2′)‐OH were synthesized. The first set consists of 4‐HOArCH=NArY and XArCH=NArOH‐4′, and the second set consists of 2‐HOArCH=NArY and XArCH=NArOH‐2′. Their ultraviolet absorption spectra were measured and investigated. A very interesting phenomenon was observed by analyzing their wave number νmax (cm−1) of longest wavelength maximum λmax (nm) of ultraviolet. Compared with the change regularity of the νmax of XArCH=NArY (where the X and Y excluded OH), the 4′‐position hydroxyl (4′‐OH) and 2′‐position hydroxyl (2′‐OH) have abnormal performance. The details are the following: the 4′‐OH contributes an additional red shift to the νmax of XArCH=NArOH‐4′ (λmax increase), whereas the 2′‐OH contributes an additional blue shift to the νmax of XArCH=NArOH‐2′ (λmax decrease). In addition, there are ortho steric effects of all 2‐OH and 2′‐OH on the νmax for 2‐HOArCH=NArY and XArCH=NArOH‐2′, and the ortho steric effect contributes a red shift to their νmax. These experimental facts can provide an important theoretical reference for us using aryl Schiff base compounds as optical materials and performing the molecular design.  相似文献
5.
The compounds stilbenes XArCH=CHArY(XSBY) and 1,2‐diphenylpropylenes XArC(Me)=CHArY(XSMBY) have bridging groups CH=CH and C(CH3)=CH, respectively, in which the C(CH3)=CH has a side‐group CH3 at the carbon‐carbon double bond. A series of XSMBY were synthesized, and their longest wavelength maximum λmax (nm) in ultraviolet absorption spectra were measured in this work. We investigated the change regularity of the νmax (cm‐1, νmax = 1/λmax) of XSMBY and compared it with that of XSBY. The results indicate that (1) there is no good linear relationship between the νmax of XSMBY and that of XSBY. (2) Because of the influence of the side‐group CH3, in case of the same couple of groups X and Y, the λmax of XSMBY is shorter than that of XSBY, that is, it has a blue shift. (3) The cross‐interaction between the side‐group CH3 and Y has an important effect on the νmax of XSMBY, while the cross‐interaction between the side‐group CH3 and X has a little effect on the νmax and can be ignored. (4) The specific cross‐interaction between X and Y has important effect on the νmax of XSMBY, whereas it has no important effect on the νmax of XSBY.  相似文献
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Based on the topological characteristics of distance matrices and adjacency matrices of molecular graphs, a new concept of organic homo‐rank compounds was proposed. Based on this concept, compounds can be classified into new groups other than the traditional homologues. Furthermore, novel structure–property relationship approach named as homo‐rank compounds method can be developed. The feasibility of homo‐rank compounds method was explored by estimating the enthalpy of formation of organic compounds. The group contribution index (GCIX) and group polarizability potential index (GPIX) of substituents X were defined and determined for mono‐substituted alkanes RX (X includes 20 substituents). The research results show that the enthalpies of formation of organic homo‐rank compounds and their isomers can be correlated very well with the parameters GCIX and GPIX. Combining the method of homologues with that of homo‐rank compounds, a general and simple quantitative correlation equation (8) was established to estimate the enthalpy of formation for RX, and the calculation precision is within the chemical accuracy ‘1 kcal/mol’. For 242 samples of RX, the average absolute deviation between the experimental and the calculated values is 2.42 kJ/mol. In addition, the enthalpies of formation of more than 2800 samples of RX were estimated. The approaches of organic homo‐rank compounds and organic homologues are independent of but complementary to each other. The combination of these two methods can help us to understand the organic molecular structure–property relationships more deeply, and to investigate these relationships more conveniently and accurately. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献
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