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 σCC()pex 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 σCC()pex 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 σCC()pex values are reliable by means of quantitative correlation method.

Sixty‐six samples of 1‐furyl/thienyl‐2‐arylethylene model compounds XCHCHArY (abbreviated XEBY) were synthesized. The nuclear magnetic resonance spectra (NMR) of model compounds were determined. The chemical shift δC(X) and δC(Y) of the carbon atoms in bridging bond CHCH which connected to the X group and the ArY group, respectively, were confirmed with the two‐dimensional NMR method. The effect of substituent on the δC(X) and δC(Y) was studied, meanwhile, the push‐pull effect of substituent on ΔδC = δC(Y) − δC(X) and δC(Y/X) = δC(Y)/δC(X) were discussed. The results show the following: (a) Both the δC(X) and δC(Y) are affected by excited‐state substituent constant σCCex()X of group X, Hammett constant σ(Y), and excited‐state substituent constant 0.25emσCCex()Y of group Y. The effect of σ(Y) on the δC(X) is positive, whereas that on the δC(Y) is negative. That is to say, the σ(Y) of group Y has an alternative influence on the δC(X) and δC(Y). (b) Compared with furyl, there is a p‐d effect formed by the 3d orbit of S atom and the p electron of the π system in thienyl, which increase the chemical shift of the carbon atoms in bridging bond. (c) The push‐pull effect between substituent X and Y is not only affected by the σ parameter but also related to the σCCex parameter, which results from the combined effect of the two parameters σ and σCCex. The observation of this paper provides a new perspective in understanding the push‐pull effect of substituent.

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To explore the substituent effects on the stretching vibration frequencies ν C=C of C=C bridge bond in 1-furyl/thienyl-2-aryl ethylene XCH=CHArYs, 60 samples of XCH=CHArYs were synthesized, and their infrared absorption spectra were recorded. The regression analyses between the ν C=C values of XCH=CHArYs and the substituent parameters of X and Y were made in detail. Finally, an optimality equation (shown as Equation 3) quantifying the ν C=C values of XCH=CHArYs was obtained. It shows that the substituent effects on the ν C=C values of XCH=CHArYs mainly reflect in Hammett constant of X and the excited-state substituent constants of X and Y. Among the parameters in Equation (3), the excited-state substituent constant of X contributes the most to the ν C=C values of XCH=CHArYs as seen from the fraction contributions. On the whole, the contribution of X to the ν C=C values of XCH=CHArYs is larger than that of Y.