Ultraviolet And Fluorescence Properties Of Silver Nanoclusters-hydroxyl Bis-aryl Schiff Base

In this work,50 samples of disubstituted bis-aryl Schiff bases containing ortho hydroxyl group 2-OH-5-XArCH=NArY and XArCH=NAr2’-OH-5-Y were synthesized,and the NMR chemical shift and UV absorption were analyzed by substituent effects.The UV absorption and fluorescence emission spectra of 119 bis-aryl Schiff bases containing hydroxyl under the action of silver nanoclusters were measured,and the influence of substituent effects on them was investigated.The main contents are as follows:（1）The influence of substituent effects on the regularty of the UV absorptionυmax for disubstituted bis-aryl Schiff bases containing ortho hydroxyl group were investigated.The result shows that there is an additional parameter?Σσ² on the influence factor of theυ_max for compound 2-OH-5-XArCH=NArY relative to XArCH=NAr2’-OH-5’-Y,and theυ_max was reduced by it.（2）The offset value（?υ）of UV absorption peak wavenumberυ(cm^-1)about bis-aryl Schiff bases containing ortho、meta and para hydroxyl（HOArCH=NArY and XArCH=NArOH）under the action of silver nanoclusters was conducted for the quantitative correlation analysis.The results showed that:In the para-hydroxyl Schiff base,the conjugate effect of substituent X has the greatest contribution to?υ,while the conjugate effect and excited-tate substituent effect of the substituent Y are smaller and can be ignored.In the ortho-hydroxy Schiff base,the group-state polarity parameter of the substituent X is the major influence factor for?υ,while the group state polarity parameter of the substituent Y is less effective and can be ignored.In the compound 3-HOBAY,the interaction of substituent Y and OH has the greatest contribution to?υ.（3）The wavenumber offset?υof bis-aryl Schiff bases containing ortho hydroxyl group under the action of silver nanoclusters were quantitatively related by the substituent effect.The group-state polarity parameters of the substituent X and Y had a great influence on?υin the XArCH=NAr2’-OH-5’-Y.while the effect on?υin the 2-OH-5-XArCH=NArY was small and can be ignored.（4）The regularity of the substituent effect on the ¹³C NMR of CH=N bond chemical shifts and the ¹H NMR of OH chemical shift valueδ_H（OH）in 2-OH-5-XArCH=NArY has been studied.It is found that the interaction between substituent X and OH has the greatest influence on them.（5）The effects of the substituent and solvent on theδ_H（OH）of 2-HOArCH=NArY were discussed.The research results show that the substituent effect is dominated by polar substituent constantσand excited-state substituent parameterσ_CC^ex of substituent Y.While the solvent effect is dominated by the n-octanol/water partition coefficient（logP）and the solvatochromic dye（E_T（30））.