Extension And Application Of Excited-state Constants Of Para-substituents And Meta-substituents

This work can be divided into two part.The first part is: Seven series of 3,4’-disubstituted stilbenes with meta-substituents X （X=NO2,I,CHCH2,Ph, Et, NMe2 and CCH） were synthesized. Their molecular structures were confirmed by 1H NMR and 13C NMR method. Their longest wavelength maximum λmax （nm） of ultraviolet absorption spectra were measured. For the wavenumbers vmax （cm-1） of 3,4’-disubstituted stilbenes,a quantitative correlation analysis was carried out,and the excited-state substituent constants σCC（m）ex of seven meta-substituents were determined by using the method of curve-fitting.Also the application of the obtained σCC（m）ex in the UV spectra of disubstituted stilbenes and aryl schiff base were explored,the main work and results are as follows:（1）The constants σCCex of meta-substituents and para-substituents were compared with Hammett constants a. The result indicates that σCCex and σexpress the substituent electrostatic effects in excited - state and ground-state, respectively.（2）10 samples of aryl Schiff bases and 14 samples of 3,3 ’-disubstituted stilbenes with meta-substituents X were synthesized, and their λmax,pred,were predicated by using the obtained constants σCC（m）ex. The results show that the λmax,pred. are in good agreement with the experimental values, which confirm the obtained σCC（m）ex values reliable.（3）We also collected vmax values of 225 samples of disubstituted stilbenes and disubstituted benzenes, and established a general quantitative equation to express the change regularity of their vma. The result indicates that the vmax of these compounds are affected by three factors: vmax,parent of parent molecule, ∑σCCex×vmax,parent and σ（XY）.The second part is: series of 2,4’-disubstituted stilbenes o-XArCH=CHArY-p were synthesized. Taking was the compounds of monosubstituted benzenes HSBY as the reaction center, using the calculation method of topology steric effect index TSEI proposed by Cao,we calculated the TSEI values of the seven ortho-substituents X （X=OMe,Me, F, Cl, Br, CF3, CN）and H atoms. the main work and results are as follows:（1）The construction method of excited-state substituent constant σ_CC（o）^ex was preliminarily explored and th σ_CC（o）^ex of seven ortho-substituents were obtained. We also established a quantitative to quantitate the vmax of compounds o-XSBY-p. The results show that the vmax of these compounds main are affected by the ∑σCCex values （the sum of excited-state substituent constants of substituents X and Y） and TSEI values of ortho-substituents.（2）10 samples of 2,3’-disubstituted stilbenes with othor-substituents X were synthesized,and their λmax,precd. were predicated by using the obtained constants σ_CC（o）^ex. The results show that the λmax,pred. are in good agreement with the experimental values, which confirm the obtained σ_CC（o）^ex values reliable.