Substituent Effect On The Spectra And Molecular Configuration Of 4, 4'-disubstituted N-benzylidenebenzenamine Derivatives

A series of 4, 4'-disubstituted N-benzylidenebenzenamine derivatives were synthesized in this paper, their melting points were measured and their molecular structures were confirmed by 1H NMR and 13C NMR. The UV spectra of the target compounds were mensurated in ethanol.The law, which is between the substituent effect and the UV spectra of 4, 4'-disubstituted N-benzylidenebenzenamine derivatives has been studied. It is indicated that UV spectra energy of 4, 4'-disubstituted N-benzylidenebenzenamine derivatives have a good correlation with excited-state substituent constants, no matter the variable of the structure of molecule is single substudent or double substudents. Polar substituent constants, radical substituent constants and excited-state substituent constants all were employed to correlate with the the UV spectra energy of 4, 4'-disubstituted N-benzylidenebenzenamine derivatives respectively, it was observed that the correlation between excited-state substituent constants and the UV spectra energy is better than that of polar substituent constants and radical substituent constants. Meanwhile, It prove that the excited-state substituent constants is appropriate for 4, 4'-disubstituted N-benzylidenebenzenamine derivatives.The law also has been studied about the effect for molecule structure due to the lone pair electrons, which exist in N atom. We synthesized 26 substituted N-phenyl-a-phenylnitrone in order to eliminate the effect of lone pair electrons. It is indicated that UV spectra of 4, 4'-disubstituted a-phenyl-N-phenylnitrone derivatives has a good correlation with only excited-state substituent constants, no matter the variable of the structure of molecule is single substudent or double substudents. Through studying crystal stuctures of 4, 4'-disubstituted N-benzylidenebenzenamine derivatives and substituted N-phenyl-a-phenylnitrone derivatives, we find the reason why the two series were correlationed with different equations, meanwhile, we also explant the red shif phenomenon.In addition, the substituent effect on 13C NMR of the C=N in benzylidene anilines XPhCH=NPhY was investigated, in XPhCH=NPhY, the substituents X and Y are in p-position or in m-position. The substituent effects including the inductive effects of X and Y, the conjugative effects of X and Y, and the interaction effect of X and Y, which were put into one model to quantify the 13C NMR chemical shiftδC(C=N) of the C=N in XPhCH=NPhY. Apenta-parameter correlation equation with correlation coefficient 0.9975 and standard error 0.17 ppm was obtained for 80 samples of compounds.