Study On The Spectroscopic Properties Of Disubstituted Schiff Bases Of O-Difluoroboryloxy Disubstituted Diaryl Schiff Base

In this paper,44 O-difluoroboroxy disubstituted diaryl Schiff base compounds were synthesized.The NMR chemical shift,ultraviolet(UV)absorption spectrum and fluorescence(FL)emission spectrum of the obtained compounds NMR were studied.The main contents are as follows:1)The result of the influence law of the UV absorption spectrum of 2-OBF₂XBAY shows that the biggest factors influencing on the?_max factor of compound 2-OBF₂XBAY's are the field/induction effect?_F(X)_O and?_F(X)_C,The contribution of both to the?_max each other is close,but their effect on the?_max is opposite.While in compound 2-HOXBAY,the biggest factor influencing on the?_max is the sum of excited state substituent parameter of substituent X?_cc^ex(X).This may be due to changes in the parent molecular structure of compound2-OBF₂XBAY and compound 2-HOXBAY,resulting in a large difference in the factors affecting the?_max of the two types of compounds.Compared with the 2-HOXBAY compounds,the?_max of all 2-OBF₂XBAY compound have obvious redshift,which may be the result of the easy of the charge transfer.2)The wave number?_Em of the solid fluorescence emission wavelength of 2-OBF₂XBAY is mainly affected by four factors:the field/induction effect of the X group?_F(X)_O and?_F(X)_C,the excited state substitution parameter of the X group_cc^ex(X),and the excited term substituent parameter interaction term?_cc^ex2 of the substituents X and Y.Compared with2-HOXBAY,the fluorescence intensity of 2-OBF₂XBAY is significantly increased,and the fluorescence emission wavelength is significantly blue-shifted.3)The result of 2-OBF₂XBAY's liquid fluorescence influence law shows that the field/induction effect of X group?_F(X)_O and?_F(X)_C contributes the most to?_Eml,and the sum of the two exceeds 70%;Compared with the quantitative equation,the interaction term has a greater effect on the fluorescence of the liquid fluorescence,but the interaction of the excited state substituent parameters in the solid fluorescence is greater than the liquid fluorescence.The effect of the substituents in the o-hydroxydisubstituted diaryl Schiff base on the fluorescence emission wavelength was explored.The solid of the o-hydroxydiaryl Schiff base can emit fluorescence,and the strong electron-donating group-NMe2 in the fluorescence emission wavelength of 2-HOBAY The emission is the longest,the fluorescence emission intensity of 2-HOBA4'-Me is the largest,and the compound with the smallest fluorescence emission intensity is 2-HOBA4'-t-Bu.4)The rule that the ¹³C NMR chemical shift value of the CH=N double bond in2-OBF₂XBAY is affected by the substituent effect is studied.It is found that the?_C(CH=N)of2-OBF₂XBAY is mainly affected by two factors:the field/induction effect of X group?_F(X)_Oand?_F(X)_C.The rule of ¹H NMR chemical shift value of CH=N double bond in 2-OBF₂XBAY affected by substituent effect was studied.2-OBF2XBAY's?_C(CH=N)is affected by the induction effect of substituent X,the substituent state parameter of the excited state of substituent X,the ground state polarity parameter of substituent Y,and the interaction term of cross-competition with the ring.The change of the electron cloud density on the bridge bond makes the change law of?_H(CH=N)on the 2-OBF₂XBAY bridge bond very different from that of 2-HO-XBAY.