Ultraviolet And Fluorescence Properties Of Supermolecular System:Silver Nanoclusters With N-(Phenyl-ethylene)-Anilines

Effect of substituents on ultraviolet?UV?absorption spectra and fluorescence?FL?emission spectra of supermolecular system involving N-?phenyl-ethylene?-anilines and silver nanoparticles was investigated.Silver nanoparticles?AgNPs?and 77 samples of model compounds?MC?,N-?phenyl-ethylene?-anilines ZArC?Me?=NArY?ZPEAY,including 40compounds 2-H-XPEAY without ortho-hydroxyl group and 37 compounds 2-OH-XPEAY with ortho-hydroxyl group?were synthesized.The size of AgNPs was characterized by transmission electron microscopy?TEM?.And the UV absorption spectra and the FL emission spectra of AgNPs,ZPEAY and MC-AgNPs solutions were measured respectively.The spectra of ¹³C NMR and ¹H NMR of 2-OH-XPEAY were measured.The ¹³C chemical shift values of C?Me?=N bridge groups,?_C[2-OH,C?Me?=N]were determined.The effect of substituents X and Y on the?_C[2-OH,C?Me?=N]were investigated quantitatively.The substituent effects on the UV absorption spectra of MC-AgNPs supermolecular system were investigated quantitatively.The results show that:?i?the size of silver nanoparticles increases in AgNPs-ZPEAY solution,compared with it in AgNPs solution,due to the absorption of ZPEAY molecules on the surface of AgNPs;?ii?the UV absorption wavelength of ZPEAY changes in AgNPs-ZPEAY solution and there is a limitation for the wavelength shift(?_WSL)between ZPEAY and AgNPs-ZPEAY system;?iii?there is a quantitative correlation between the wavenumber??_WSLSL of?_WSLSL and the substituent constants(Hammett constant?and excited-state substituent constant?_CC^exof substituents X and Y;?iv?the intramolecular hydrogen bonding in 2-OH-XPEAY makes the?_WSLSL a blue shift in AgNPs-ZPEAY system.By using the quantitative correlation analysis of?_maxax of 2-OH-XPEAY and comparing the change regularity of their?_maxax with that of 2-H-XPEAY and 2-OH-XBAY?2-OH-XArCH=NArY?,we obtained that the factors influencing the?_maxax of them are different.The addition of methyl group to the bridging group makes group-state polar electronic effect???has important effects on the?_maxax of 2-H-XPEAY,whereas the influence of the?constants of X and Y on the?_maxax of 2-OH-XBAY is negligible.The steric effect resulting from the methyl group at the bridging group contributes a blue shift to the?_maxax of 2-OH-XPEAY.The intramolecular hydrogen bonding of 2-OH-XPEAY has influence on the?_maxax of2-OH-XPEAY.Comparison of ¹³C NMR of C?Me?=N bond chemical shifts?_C[2-OH,C?Me?=N]in2-OH-XPEAY with that in 2-H-XPEAY was carried out.The results shows that the factors affecting the?_C[2-OH,C?Me?=N]of 2-OH-XPEAY are quite different from that of?_C[C?Me?=N]of 2-H-XPEAY.A five-parameter correlation equation with correlation coefficient 0.9605 was obtained for quantifying the?_C[2-OH,C?Me?=N].The result indicates that the?_C[2-OH,C?Me?=N]of 2-OH-XPEAY is dominated by polar electronic effect of Y[??Y?]and excited-state substituent constant of Y[?_cc^ex?Y?].Also the?_C[2-OH,C?Me?=N]of2-OH-XPEAY was compared with the?c[C?Me?=N]of C?Me?=N bridge group in2-H-XPEAY.It shows there is no good linear relationship between the?_C[2-OH,C?Me?=N]and?c[C?Me?=N]due to the intramolecular hydrogen bond in 2-OH-XPEAY.Therefore one cannot only use the change of?c[C?Me?=N]to deduce the change of?_C[2-OH,C?Me?=N]in confirming the organic molecule structures with NMR spectra.