[Study on synthesis and relation between structure and optical properties of stilbene derivatives]

In the present paper, three stilbene derivatives with different substitutions were synthesized by phase-transfer Wittig reaction and Pd(II)-catalyzed heck reaction. The molecular structures were characterized by FTIR, elemental analysis and 1H NMR spectra. The authors investigated the influence of molecular structure on electron absorption spectra and luminescence-emitting properties. The results show that compared with that of compound 3a without substitution with a maximum electron absorption peak at 356 nm, the substitution of CH3 group results in a slightly red-shift of electron absorption peak wavelength of molecules to 358 nm, while the substitution of NO2 group makes molecule possess larger pi electron conjugation and the maximum absorption peak shifts to a longer wavelength region (388 nm). Simultaneously, it was found that the substitution of CHR3 group yields luminescence emission with a peak wavelength at 414 nm and the luminescence emission strength significantly increases in comparison with that of compound 3a without substitution. On the contrary, the substitution of electron-acceptor NO2 group results in the decrease in luminescence emission strength with an emission maximum wavelength at 525 nm. Therefore, the structure of substitution on stilbene molecules has an important effect on their optical properties and this will provide some foundation for the structure design of emitting molecules in future.