Substituent effect on the UV spectra of p‐disubstituted compounds XPh(CHCHPh)_nY (n = 0, 1, 2)

Abstract

Three parameters, ${\rm \sigma }_{\rm CC}^{\rm ex} $, ${\rm \sigma }_{\rm CC}^{\rm ex} ({\rm XY)}$ and $\upsilon_{{\rm max,}\,{\rm parent}} $, are developed to express the substituent effect and the effect of the parent molecular structure of p‐disubstituted compounds XPh(CHCHPh)nY (n = 0, 1, 2). The investigated result shows a good correlation between the UV absorption wavenumbers (υmax) and the three parameters for a diverse set of title compounds, and the correlation equation can be used to predict the UV absorption energy of compounds with the mentioned structure. This approach provides a new insight for the quantitative structure‐property relationship (QSPR) correlation of the UV absorption energy of p‐disubstituted homologues. Copyright © 2010 John Wiley & Sons, Ltd.

Determining the excited‐state substituent constants of meta‐substituent from 3,4'‐disubstituted stilbenes

“… The value of Et was taken from ref . the value of PhO was calculated according to the method of ref .…”

“…Recently, Cao C. et al . proposed a new excited‐state substituent parameter, , and recommended the single‐parameter equation () or the dual‐parameter equation ( σ p and ) to correlate the UV absorption wavenumbers ( υ max ) of compounds with monosubstituent changed, and then he and co‐workers use this excited‐state substituent parameter to study successfully the UV absorption wavenumbers of compounds with disubstituent changed, as 1,4‐disubstituted benzenes, 4,4'‐disubstituted stilbenes and 4,4'‐disubstituted N‐benzylidenebenzenamines, etc.…”

“…Cao's reported works focus mainly on the υ max of compounds with the para‐substituents and did not investigate the υ max of the compounds with the meta‐substituents, due to the lack of the values of meta‐substituents. Therefore, it is meaningful to get the excited‐state substituent constants of meta‐substituents for extending the application of the in the optical materials.…”

Effects of substituent and solvent on the UV absorption energy of 4,4′-disubstituted stilbenes

“…If the 4,4'-disubstituted stilbene derivatives is to be used as optical materials, the effects of substituent and solvent on their UV absorption energy must be known. In author's recent works [16][17][18], the excited-state substituent parameter ex CC  was proposed to scale the effect of intramolecular substituent effect. It is found that the energy of UV absorption max wavelengths of trans-4,4'-disubstituted stilbene derivatives (XPhCH=CHPhY) can be correlated well with two parameters in a given solvent, the sum of ex CC  of substituents X and Y and the interaction between substituents X and Y, ex CC  (X) ex CC  (Y), in which the correlation result using parameter ex CC  is better than that of using polar substituent constant  x or spin-delocalization substituent constant  • [16][17][18].…”

“…of XSBY in a given solventFrom our previous studies[18], it was known that the energy of UV absorption max wavelengths of 4,4'-disubstituted stilbenes in ethanol has a good correlation with the ex CC  of substituents X and Y. Thus, we also attempt to correlate the energy of UV absorption max wavelengths (wavenumbers max  ) of XSBY with two parameters…”