Determining the excited-state substituent constants σ_CC~(ex) of meta-substituent from 3,4,-disubstituted stilbenes

摘要

In this paper, 61 samples of 3,4'-disubstituted stilbenes and 18 samples of 3,3'-disubstituted stilbenes were synthesized, and their UV data were measured in anhydrous ethanol. Based on the UV absorption energy (wavenumber) of 3f4'-disubstituted stilbenes, the excited-state substituent constants of meta-substituent were determined by means of curve-fitting. The availability of σ_(CC)~(ex)(m) was confirmed by the good correlation with the UV absorption energy of 3,4'-disubstituted stilbenes and 4,4'-disubstituted stilbenes. Further, using the obtained constants tr_(CC)(m))~(ex)and the correlation equation, we calculated the UV wavenumbers of 3,3'-disubstituted stilbenes, and the calculated wavenumbers are in good agreement with the experimental values. These results verified that the excited-state substituent constants of meta-substituent are reliable parameter to scale the effect of meta-substituent on the UV absorption energy.